Дисертації: "Emerging and re-emerging infectious diseases"

1

Dorigatti, Ilaria. "Mathematical modelling of emerging and re-emerging infectious diseases in human and animal populations." Doctoral thesis, Università degli studi di Trento, 2011. https://hdl.handle.net/11572/369140.

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The works presented in this thesis are very different one from the other but they all deal with the mathematical modelling of emerging infectious diseases which, beyond being the leitmotiv of this thesis, is an important research area in the field of epidemiology and public health. A minor but significant part of the thesis has a theoretical flavour. This part is dedicated to the mathematical analysis of the competition model between two HIV subtypes in presence of vaccination and cross-immunity proposed by Porco and Blower (1998). We find the sharp conditions under which vaccination leads to the coexistence of the strains and using arguments from bifurcation theory, draw conclusions on the equilibria stability and find that a rather unusual behaviour of histeresis-type might emerge after repeated variations of the vaccination rate within a certain range. The most of this thesis has been inspired by real outbreaks occurred in Italy over the last 10 years and is about the modelling of the 1999-2000 H7N1 avian influenza outbreak and of the 2009-2010 H1N1 pandemic influenza. From an applied perspective, parameter estimation is a key part of the modelling process and in this thesis statistical inference has been performed within both a classical framework (i.e. by maximum likelihood and least square methods) and a Bayesian setting (i.e. by Markov Chain Monte Carlo techniques). However, my contribution goes beyond the application of inferential techniques to specific case studies. The stochastic, spatially explicit, between-farm transmission model developed for the transmission of the H7N1 virus has indeed been used to simulate different control strategies and asses their relative effectiveness. The modelling framework presented here for the H1N1 pandemic in Italy constitutes a novel approach that can be applied to a variety of different infections detected by surveillance system in many countries. We have coupled a deterministic compartmental model with a statistical description of the reporting process and have taken into account for the presence of stochasticity in the surveillance system. We thus tackled some statistical challenging issues (such as the estimation of the fraction of H1N1 cases reporting influenza-like-illness symptoms) that had not been addressed before. Last, we apply different estimation methods usually adopted in epidemiology to real and simulated school outbreaks, in the attempt to explore the suitability of a specific individual-based model at reproducing empirically observed epidemics in specific social contexts.

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2

Dorigatti, Ilaria. "Mathematical modelling of emerging and re-emerging infectious diseases in human and animal populations." Doctoral thesis, University of Trento, 2011. http://eprints-phd.biblio.unitn.it/458/2/thesis_Dorigatti_2.pdf.

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Анотація:

The works presented in this thesis are very different one from the other but they all deal with the mathematical modelling of emerging infectious diseases which, beyond being the leitmotiv of this thesis, is an important research area in the field of epidemiology and public health. A minor but significant part of the thesis has a theoretical flavour. This part is dedicated to the mathematical analysis of the competition model between two HIV subtypes in presence of vaccination and cross-immunity proposed by Porco and Blower (1998). We find the sharp conditions under which vaccination leads to the coexistence of the strains and using arguments from bifurcation theory, draw conclusions on the equilibria stability and find that a rather unusual behaviour of histeresis-type might emerge after repeated variations of the vaccination rate within a certain range. The most of this thesis has been inspired by real outbreaks occurred in Italy over the last 10 years and is about the modelling of the 1999-2000 H7N1 avian influenza outbreak and of the 2009-2010 H1N1 pandemic influenza. From an applied perspective, parameter estimation is a key part of the modelling process and in this thesis statistical inference has been performed within both a classical framework (i.e. by maximum likelihood and least square methods) and a Bayesian setting (i.e. by Markov Chain Monte Carlo techniques). However, my contribution goes beyond the application of inferential techniques to specific case studies. The stochastic, spatially explicit, between-farm transmission model developed for the transmission of the H7N1 virus has indeed been used to simulate different control strategies and asses their relative effectiveness. The modelling framework presented here for the H1N1 pandemic in Italy constitutes a novel approach that can be applied to a variety of different infections detected by surveillance system in many countries. We have coupled a deterministic compartmental model with a statistical description of the reporting process and have taken into account for the presence of stochasticity in the surveillance system. We thus tackled some statistical challenging issues (such as the estimation of the fraction of H1N1 cases reporting influenza-like-illness symptoms) that had not been addressed before. Last, we apply different estimation methods usually adopted in epidemiology to real and simulated school outbreaks, in the attempt to explore the suitability of a specific individual-based model at reproducing empirically observed epidemics in specific social contexts.

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3

Zwart, Onno de. "Exploring risk perceptions of emerging infectious diseases." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2009. http://hdl.handle.net/1765/14759.

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4

Mableson, Hayley Elizabeth. "The disease-scape of the new millennium : a review of global health advocacy and its application." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/17855.

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The global disease scape is constantly shifting, influenced by demographic transitions, altering the balance of the burden of infectious and non‐communicable diseases. The epidemiological transitions can be divided into three stages: the first, an increase in infectious disease burden as populations settled, then grew into towns and cities providing conditions for infectious agents to maintain spread; the second transition follows industrialisation, changes in lifestyle, diet and improved sanitation whereby infectious diseases are reduced and non‐communicable disease (NCD) prevalence increases; the third transition describes the re‐emergence of infectious diseases as the AIDS epidemic and other emerging and re‐emerging disease outbreaks lead to an increasing burden of infectious diseases, particularly in developing countries. Analysis of the disease‐scape has been carried out using WHO Global Burden of Disease data and correlation to demographic factors calculated using World Bank Development Indicators. The balance of chronic NCDs and infectious diseases can be represented numerically as the unit rate of infectious to non‐communicable diseases. The rate, which indicates at which end the continuum lies can then be correlated to these demographic development indicators to assess the factors which are influential to the continuum. As the balance of infectious and non‐communicable diseases around the world alters, the focus of the advocacy at the global health level has been examined to assess if the trends follow that of the shifting continuum. This has been carried out through an assessment of the WHO World Health Assembly (WHA) resolutions adopted annually between 1948 and 2013 on the subject of infectious and/or non-communicable diseases. The principle of International health stemmed from the need to contain the international spread of communicable diseases, so it is not surprising that in the first decade of the WHO, 88% of the resolutions adopted for infectious and non‐communicable disease were adopted for infectious diseases. In the latest ten years of the WHO, 72% of the Assembly resolutions for infectious and non‐communicable diseases were focused on infectious diseases; this indicates that while there has been a shift in the balance, the adopted resolutions still focus heavily on infectious diseases. An example of how advocacy can elevate diseases to a higher position on the global health agenda is that of the Neglected Tropical Diseases. Following the Millennium Development Goals, this group of seventeen diseases has been highlighted as being “neglected” in terms of funding, research and political will. A review of the campaign to highlight this shows how global health advocacy can elevate diseases to a prominent position on the global health agenda. With this in mind, the advocacy for a sub‐group of Neglected Zoonotic Diseases has been examined at the WHA level. The results highlight the sporadic nature of support to control these diseases, and that activism for control of some of the major zoonotic diseases remains lacking. Rabies is explored as an example of a disease for which there are recommendations and support at the global level for the control and elimination of the disease, but for which barriers to control exist locally in endemic countries. The advocacy for diseases at the global health level has the possibility to impact the priorities of health care within individual nations. However the advocacy at this level may take time to reflect the changes within the disease‐scape. The impact of such advocacy is also limited by local political will, availability of resources and local cultural implications. Therefore there is a need to ensure that efforts to control diseases are tailored to specific populations and that resources are made available to support the advocacy.

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5

Rivers, Caitlin. "Modeling Emerging Infectious Diseases for Public Health Decision Support." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/52023.

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Emerging infectious diseases (EID) pose a serious threat to global public health. Computational epidemiology is a nascent subfield of public health that can provide insight into an outbreak in advance of traditional methodologies. Research in this dissertation will use fuse nontraditional, publicly available data sources with more traditional epidemiological data to build and parameterize models of emerging infectious diseases. These methods will be applied to avian influenza A (H7N9), Middle Eastern Respiratory Syndrome Coronavirus (MERS-CoV), and Ebola virus disease (EVD) outbreaks. This effort will provide quantitative, evidenced-based guidance for policymakers and public health responders to augment public health operations.
Ph. D.

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6

Brierley, Liam. "The ecology of emerging diseases : virulence and transmissibility of human RNA viruses." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/22067.

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Emerging infectious diseases continue to represent serious threats to global human health. Novel zoonotic pathogens are continually being recognised, and some ultimately cause significant disease burdens and extensive epidemics. Research and public health initiatives often face emerging pathogens with limited knowledge and resources. Inferences from empirical modelling have begun to uncover the factors determining cross-species transmission and emergence in humans, and subsequently guide risk assessments. However, the dynamics of virulence and transmissibility during the process of emergence are not well understood. Here, I focus on RNA viruses, a priority pathogen type because of their potential for rapid evolution. I use comparative trait-based analyses to investigate how aspects of both host and virus ecology contribute to the risk of virulence and transmissibility within human RNA viruses. To explore these questions, data were collected via systematic literature search protocols. In the first half of this thesis, I focus on viral determinants of virulence and transmissibility. I ask whether virulence can be predicted by viral traits of tissue tropism, transmission route, transmissibility and taxonomic classification. Using a machine learning approach, the most prominent predictors of severe virulence were breadth of tissue tropism, and nonvector-borne transmission routes. When applied to newly reported viruses as test set, the final model predicted disease severity with 87% accuracy. Next, I assess support for hypothesised routes of adaptation during emergence using phylogenetic state-switching models. Propensity for adaptation in small ‘stepwise’ movements versus large ‘off-the-shelf’ jumps differed between virus taxa, though no single route dominated, suggesting multiple independent trajectories of adaptation to human hosts. In addition, phylogenetic regressions showed vector and respiratory-transmitted viruses to be more likely to progress through early stages of emergence. In the second half of this thesis, I focus on how dynamics of virulence and transmissibility differ with respect to nonhuman host diversity, identity, and ecology. Using a regression framework, I observe that viruses with a broader mammalian host range exhibited higher risk of severe virulence, but lower risk of transmissibility, which may reflect potential trade-offs of host specificity. Furthermore, viruses with artiodactyl hosts exhibited lower risk of severe virulence and viruses with bat or nonhuman primate hosts exhibited higher risk of transmissibility. Next, I test hypotheses that mammal species with faster-paced life history may be predisposed to host viruses with greater virulence and transmissibility. Mammal body mass was used as an established proxy for pace of life history. In regression analyses, mammals with faster-paced life history hosted more viruses with severe virulence, though evidence for a relationship with transmissibility was limited. The broad-scale associations presented in this thesis suggest the evolution of virulence and human-to-human transmissibility during zoonotic emergence is a multifactorial, highly dynamic process influenced by both virus and host ecology. Despite this, general characteristics of high-risk emerging viruses are evident. For example, severe virulence was associated with broad niche diversity of both tissue tropisms at the within-host scale, and host species at the macroecological scale. However, risk factors for virulence and human-to-human transmissibility often did not coincide, which may imply an overarching trade-off between these traits. These analyses can contribute to preparedness and direction within public health strategies by identifying likely candidates for high-impact emergence events among previously known and newly discovered human viruses. The inherent connectivity between RNA viruses, their nonhuman hosts and the resulting implications for human health emphasise the holistic nature of emerging diseases and supports the One Health perspective for infectious disease research.

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7

Meredith, Anna Louise. "Evaluation of predators as sentinels for emerging infectious diseases." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/6480.

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New and emerging diseases in human and animal populations appear to be predominately associated with generalist pathogens that are able to infect multiple hosts. Carnivores are susceptible to a wide range of these pathogens and can act as effective samplers of their vertebrate prey, which are important reservoirs of many emerging diseases. This thesis evaluates the utility of carnivores as sentinels for pathogens present in their prey by exploration of four selected pathogen-prey-sentinel combinations in three rural study sites of varying habitat in northern England and Scotland over a twenty-two month period (2007-2009). Selected pathogens were Coxiella burnetii, Leptospira spp., Encephalitozoon cuniculi, and rabbit haemorrhagic disease virus (RHDV), selected prey species were wild rodents and rabbits, and selected carnivores were foxes, domestic cats and corvids. Seroprevalence to C.burnetii, Leptospira spp and E.cuniculi was assessed using adapted or novel test methodologies to enable their use for multiple mammalian species, however these were not applicable to corvids. RHDV seroprevalence was not assessed due to low acquisition of rabbit samples. Overall, seroprevalence to all three pathogens was significantly higher in predators than prey, at 24.2% and 12.4 % for C.burnetii, 22.73% and 1.95% for Leptospira spp and 39.06% and 5.31% for E.cuniculi in predator and prey species respectively. A similar pattern was found in all study areas and was consistent irrespective of individual prey or predator species, although serological evidence of exposure to E.cuniculi was not detected in domestic cats in any area. A semi-quantitative assessment of the time and financial costs of the study approach and application to hypothetical examples indicates that sampling carnivores is a much more costeffective approach to pathogen detection than sampling prey. The results indicate that carnivores can act as useful sentinels for broad-scale detection of pathogen presence and relative levels of prevalence in prey and predator populations. Careful selection of predator species and methods of sample acquisition are necessary to maximise their utility, and issues associated with diagnostic test performance and validation must also be acknowledged. Suggestions are made as to how this principle might be applied to future surveillance programmes. In addition, the study is the first report on the seroprevalence of C.burnetii, Leptospira spp and E.cuniculi in multiple wildlife species (field voles, bank voles, wood mice, foxes), the first detection of antibodies to C. burnetii in wildlife and cats, the first detection of antibodies to L mini, L hardjo prajitno and L hardjo bovis in wild rodents, and to L mini in cats, and the first detection of antibodies to E.cuniculi in wild rodents and foxes in the UK.

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8

Kraemer, Moritz U. G. "The distribution and spread of emerging human infectious diseases." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:05011dd4-ea3d-426a-b94b-6b617c331332.

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Despite many successes in the control of human infectious diseases they continue to pose a considerable risk to human health. The global distributions of pathogens are driven by ecological factors and the magnitude and extent of transmission are influenced by the dynamics of human behaviour. Viruses such as chikungnunya virus, Zika virus, dengue virus, and Ebola virus have recently expanded geographically. However, prior to their expansion there was little quantitative evidence available to identify locations that may be susceptible to transmission and to evaluate the likelihood of virus introduction to such locations. In this thesis statistical modelling techniques were applied with the aim of understanding infectious disease ecology, determining the main drivers of disease occurrence, and predicting the magnitude and regional spread of an outbreak in real-time. My results provide estimates of the populations now living in areas with possible transmission of chikungunya virus, show that the seasonal dynamics of Zika infection coupled with data on international travel, can better predict the arrival of the virus into new locations. Analyses of regional outbreaks of viruses including Ebola virus in West Africa and Yellow fever virus in Angola and the Democratic Republic Congo, show that patterns of human mobility strongly predict the real-time spread of disease. Further, I demonstrate that the impact of human movement varies considerably depending on the time of the outbreak (expanding versus declining phase) and the country of interest. The results and conclusions of these studies are discussed in the context of improving our understanding of infectious disease dynamics and of informing public health policies, interventions, and control efforts.

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9

Song, Wei Ash, and 宋威. "Demographic determinants of risk perception of newly emerging respiratory infectious diseases." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46941617.

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10

Amoruso, Michelle. "Re-emerging infectious disease and ethnic stratification Dengue fever in Trinidad and Tobago /." Ann Arbor, Mich. : ProQuest, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3244457.

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Thesis (Ph.D. in Anthropology)--S.M.U., 2007.
Title from PDF title page (viewed Mar. 18, 2008). Source: Dissertation Abstracts International, Volume: 67-12, Section: A, page: 4593. Adviser: Carolyn Sargent. Includes bibliographical references.

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11

Stewart, Jennifer Diane. "Genomic responses of ambystomatid salamanders to infection with an emerging virus." Online access for everyone, 2008. http://www.dissertations.wsu.edu/Thesis/Summer2008/J_Stewart_072208.pdf.

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12

Yoshikawa, Minako. "Research on Emerging and Re-emerging Mosquito-borne and Related Infectious Diseases in Southeast Asia: Prescriptions from the City-State of Singapore and a Tourist Destination of Bali, Indonesia." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157864.

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13

Ricci, James Benjamin. "The State, International Society, and Infectious Diseases : Emerging security threats and international cooperation." Thesis, University of Kent, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504663.

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14

Morris, Aaron L. "Identifying biological and environmental indicators of emerging infectious diseases : the case of Buruli ulcer." Thesis, Bournemouth University, 2014. http://eprints.bournemouth.ac.uk/22503/.

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Understanding disease ecology is vital in preventing future outbreaks of established infections and to predict the emergence of new pathogens. In recent decades there have been a number of high profile infectious diseases which have swept across countries and in some cases the world. Many of these begin as generalist emerging infections; such microbes are difficult to study in the wild due to their inherently ambiguous life histories and complex associations with numerous hosts and the environment. In this PhD a number of techniques are used to pinpoint and further understand the life history of one such pathogen Mycobacterium ulcerans, the causative agent of Buruli ulcer, in the hope that this data can be used to predict and prevent future outbreaks and can be applied to other emerging infections. The results of this study include the first identification of the pathogen in the environment for a whole new continent, South America. Further to this it has led to the discovery of the likely ecological niche of the bacilli by linking its presence to specific functional groups of organisms. In turn the occurrences of these groups have been related to anthropogenic conditions such as deforestation and human mediated land use. Finally complex links between climatic fluctuations and outbreaks of the disease in Southern America and Cameroon, central Africa help complete our understanding of this mysterious disease.

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15

Steele, Sandra Gayle. "Operationalising One Health: preparedness and response to zoonoses and emerging infectious diseases in Australia." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/27256.

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The interconnectedness of human, animal and environmental health necessitates a One Health approach to ensure effective preparedness and response to EIDs and zoonoses. The overall aim of the research contained in this thesis is to identify pathways to operationalise One Health in Australia. The specific objectives were: i) Establish a vision for One Health in clinical practice; ii) Explore system level obstacles to disease investigation and management, particularly for EIDs and zoonoses; iii) Investigate operationalisation of One Health within Australian governance structures, health systems and clinical practice; and iv) Develop a strategy to facilitate operationalisation of One Health using a health system framework. A Delphi Survey using a panel of ‘One Health experts’ was used to establish research priorities and provide a vision of One Health in clinical practice. Parallel surveys of GPs and veterinarians explored practitioner experience with zoonoses, their level of concern, their confidence in diagnosis, management and treatment of zoonoses and willingness to engage in cross-professional practices. Analysis of qualitative data enabled identification of constraints faced by veterinarians in investigating atypical disease presentations which may be zoonotic. Key informant interviews enabled us to explore the contributions and experiences of individual veterinarians during COVID-19. Their insights provided evidence of the need for effective One Health systems to ensure Australia and the world can meet the continuing challenges of COVID-19 and future pandemics. This thesis provides an evidence base to address gaps and obstacles to operationalisation of One Health in Australia. Upskilling GPs and veterinarians through educational interventions will provide capacity and preparedness to clinical practitioners. Embedding One Health into existing health systems is necessary to optimise both national and global preparedness and response to EIDs and zoonoses.

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16

Jennings, Grace. "A policy analysis of biological warfare defence and emerging infectious diseases in an international context." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.550383.

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17

Ouma, David Omondi. "Bionomics of vector-borne diseases in sites adjacent to lakes Victoria and Baringo in Kenya." Thesis, University of the Western Cape, 2016. http://hdl.handle.net/11394/5338.

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Philosophiae Doctor - PhD
Bionomics of vector-borne pathogens (VBPs) is a complex phenomenon that involves understanding the ecology of arthropod borne pathogens and vertebrate hosts potentially involved in their transmission cycles. Investigations into the bionomics of viral and bacterial VBPs circulating in Baringo and Homa Bay Counties of Kenya were carried out. Specifically, vertebrate hosts represented in mosquito bloodmeals, presence of arboviruses in blood fed mosquitoes and patients presenting with acute undiagnosed febrile illnesses in rural health facilities, and tick borne pathogens (TBPs) diversity in ticks of animals were identified. Mosquitoes were trapped by BG sentinel and CDC light traps, while ticks were sampled directly from domestic animals and tortoises close to human habitation along the shores and adjacent islands of Lakes Victoria and Baringo in Kenya. Blood and sera were also sampled from patients presenting with acute febrile illnesses visiting four rural health facilities in Homa Bay County. Mosquitoes and ticks were sorted and identified to species using standard morphological taxonomic keys. All the biological samples (blood-fed mosquitoes, ticks and blood/sera) were processed using molecular and culture procedures for detection of VBPs (arboviruses, Ehrlichia, Anaplasma, Rickettsia and protozoa). Among 445 blood-fed Aedeomyia, Aedes, Anopheles, Culex, Mansonia, and Mimomyia mosquitoes, 33 bloodmeal hosts were identified including humans, eight domestic animal species, six peridomestic animal species and 18 wildlife species. Further detection of Sindbis and Bunyamwera viruses was done on blood-fed mosquito homogenates by Vero cell culture and RTPCR in Culex, Aedeomyia, Anopheles and Mansonia mosquitoes from Baringo that had fed on humans and livestock. In TBPs assay, 585 tick pools were analysed consisting of 4,126 ticks collected in both study areas. More ticks were sampled in Baringo (80.5%), compared to Homa Bay (19.5%). In Baringo, agents of ehrlichiosis were detected from Amblyomma and Rhipicephalus ticks including Ehrlichia ruminantium (12.3%), Ehrichia canis (10.5%) and Paracoccus sp. (4.4%). Agents of anaplasmosis included Anaplasma ovis (7.2%), Anaplasma platys (4.4%) and Anaplasma bovis (4.0%), all from Hyalomma, Amblyomma and Rhipicephalus ticks, as well as agents of rickettsiosis, including Rickettsia africae, Rickettsia aeschlimannii, Rickettsia rhipicephali, Rickettsia montanensis and a Rickettsia sp. that was not conclusively characterized. Babesia caballi, Theileria sp. and Hepatozoon fitzsimonsi were also detected from both Rhipicephalus ticks and Amblyomma ticks. In Homa Bay, Ehrichia ruminantium (17.5%) and Ehrichia canis (9.3%) were isolated from Amblyomma latum and Rhipicephalus pulchellus, as well as Anaplasma platys (14.4%) and Anaplasma ovis (14.4%) from Amblyomma and Rhipicephalus species. In determination of the occurrence of arboviruses among patients presenting with acute febrile illnesses, acute Bunyamwera 3 (0.9%) and Sindbis 2 (0.6%) infections were detected by RT-PCR and cell culture and Sindbis seroprevalence was determined by plaque assay. Though a significant proportion of these patients tested positive for low Plasmodium parasitemia, none were co-infected with Plasmodium parasites and arboviruses. This study highlights the presence and relative importance of zoonotic VBPs in both study areas.

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18

Methot, Pierre-Olivier. "Historical epistemology of the concept of virulence : molecular, ecological, and evolutionary perspectives on emerging infectious diseases in the 19th and 20th century." Thesis, University of Exeter, 2011. http://hdl.handle.net/10036/3494.

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This thesis focuses on the trajectory of the biomedical concept of virulence from 1880 until the present. Following the concept across disciplinary boundaries, from a longue durée history perspective, it explores how virulence was shaped through two distinct, although sometimes overlapping, “styles of reasoning”. Located at the intersection of several distinct research domains in biology and medicine, the concept of virulence provides, in addition, a window into the complex and changing relations between evolutionary biology and the health sciences (broadly construed) over the past two centuries. Moving back and forth between field experiments and the laboratory, this work examines, through the lens of historical epistemology, the emergence of what I call the molecular and the ecological styles, and their respective conceptual practices. It focuses on the ways in which these styles operationalize the distinction between virulent or avirulent organisms in sometimes opposite sense: Whereas in the molecular (or endogenous) style the expression of virulence is explained by properties of internal structures of the infectious agent (e.g. polysaccharide capsule, virulence gene, or pathogenicity island), the concept of virulence in the ecological (or exogenous) style reflects, in contrast, either a lack of adaptation between two species (avirulence hypothesis) or the existence of one or more ecological compromises between, say, the mode of transmission of a pathogen and its host’s recovery rate (trade-off model). Both styles can be said to originate in the medical bacteriology of the late-nineteenth century, but while the former grew mostly out of the work of Louis Pasteur and Robert Koch in Europe, the latter was primarily shaped by Theobald Smith in the United States. Nearly a century later, the introduction of the category of emerging infectious disease within public health discourses in the mid-1990s facilitated a rapprochement between the two styles that had, so far, remained apart. Employing the 1918–1919 influenza pandemic as an example in which to illustrate the trajectory of the molecular and the ecological approaches, the diversity of explanatory schemes developed to account for the pandemic’s exceptional virulence points toward an unresolved, and yet productive, epistemic tension between the two styles, on the one hand, and the intrinsic polarity of the concept of virulence itself, on the other.

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19

Natsopoulou, Myrsini Eirini [Verfasser], R. J. [Akademischer Betreuer] Paxton, H. Michael G. [Akademischer Betreuer] Lattorff, and Mark J. [Akademischer Betreuer] Brown. "Emerging infectious diseases of honey bees : within host interactions ; [kumulative Dissertation] / Myrsini Eirini Natsopoulou ; R. J. Paxton, H. Michael G. Lattorff, Mark J. Brown." Halle, 2016. http://d-nb.info/1116951711/34.

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20

Peterka, Cássio Roberto Leonel. "Avaliação do efeito da fragmentação florestal na diversidade de carrapatos e patógenos transmitidos por carrapatos ma região do Pontal Paranapanema, SP." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/10/10134/tde-17042009-144842/.

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Avaliou-se o impacto da fragmentação florestal na diversidade de carrapatos de vida-livre e a presença de patógenos nestes carrapatos em remanescentes florestais do Pontal do Paranapanema, estado de São Paulo, Brasil. Estes fragmentos florestais abrigam uma rica e importante biodiversidade, com espécies endêmicas e ameaçadas como o mico-leão-preto (Leontopithecus chrysopygus), a anta (Tapirus terrestris), a onça pintada (Panthera onca), o macuco (Tinamus solitarius) e várias outras espécies de aves, mamíferos, répteis, anfíbios e peixes. Aproximadamente 90% das espécies de carrapatos parasitam exclusivamente hospedeiros selvagens. O restante pode ter animais domésticos e humanos como hospedeiros. Embora a maioria das pesquisas tenha sido dirigida a espécies de importância econômica, os carrapatos que parasitam animais selvagens possuem relevante papel na manutenção dos níveis de patógenos em populações de vida livre. Algumas destas espécies, por exemplo, demonstraram que podem parasitar hospedeiros não selvagens e promover o surgimento de zoonoses. Em habitats fragmentados, a diversidade de espécies vertebradas é menor se comparado a habitats com pouca alteração antrópica. Portanto, a fragmentação do habitat diminui a diversidade de espécies de carrapatos também. Para estudar a relação entre a fragmentação florestal e a ecologia das populações de carrapatos foram coletados carrapatos em 8 fragmentos florestais pelo método de arrasto de flanela e inspeção visual da vegetação. Os índices de comparação utilizados foram de similaridade de Jaccard, de diversidade de Shannon e complexidade do fragmento florestal de Patton. Utilizou-se o modelo de regressão linear para compara os índices de Shannon e Patton. Um total de 2149 ninfas de Amblyomma spp foi coletado e foram identificadas as espécies de 629 carrapatos. As espécies coletadas foram Amblyomma cajennense (94,28%), A. coelebs (1,59%), A. naponense (2,86%), A. ovale (0,64%), A. nodosum (0,32%), A. brasiliense (0,16%) e Haemaphysalis juxtakochi (0,16%). Nenhum indivíduo testado foi positivo pelo teste da hemolinfa. Os resultados mostraram uma tendência de correlação entre a fragmentação floresta, e a diversidade de espécies de carrapatos.
This study evaluated the impact of forest fragmentation on diversity of freeliving ticks and prevalence of tick pathogens in remaining forest fragments in the Pontal do Paranapanema, São Paulo state, Brazil. These forest fragments shelter rich and important biodiversity, with endemic and threatened species such as the black lion tamarin (Leontopithecus chrysopygus), the tapir (Tapirus terrestris), jaguar (Panthera onca), the solitary tinamou (Tinamus solitarius) and various other species of birds, mammals, reptiles, amphibians and fish. Approximately 90% of tick species parasitize exclusively wild hosts. The remainder can also have domestic animals and humans as hosts. Although most research has been directed to species of economic importance, ticks that parasitize wild animals are also relevant due to their role in maintaining enzootic pathogen levels in wild populations. Some of these species, for example, have been shown to cross-over onto non-wild hosts and promote emergent zoonoses. In fragmented habitats, the diversity of vertebrate species is normally lower than comparable habitats with minimal anthropic alteration. Thus, habitat fragmentation decreases the diversity of tick species too. To study the relationship between forest fragmentation and population ecology of ticks, ticks were collected in 8 forest fragments using dragging and visual inspection of vegetation. The index used were Jaccard´s similarity, diversity f Shannon and Patton. The linear regression model was used to compare Shannon and Patton indexes. A total of 2149 nymphs of Amblyomma spp. And 629 identified ticks was collected. The species of ticks collected was Amblyomma cajennense (94,28%), A. coelebs (1,59%), A. naponense (2,86%), A. ovale (0,64%), A. nodosum (0,32%), A. brasiliense (0,16%) e Haemaphysalis juxtakochi (0,16%). All ticks were negative by hemolimph test. The results showed a tendency of correlation between forest fragmentation and diversity of tick species.

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Cappelle, Julien. "Évaluation éco-épidémiologique du risque démergence du virus Influenza Aviaire Hautement Pathogène H5N1 dans le Delta Intérieur du Niger au Mali via lavifaune sauvage." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20080/document.

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Cette thèse évalue le risque d'émergence d'un pathogène via l'avifaune sauvage dans une région indemne en combinant deux approches : 1) L'étude de pathogènes partageant des caractéristiques éco-épidémiologiques communes avec le pathogène émergeant. 2) L'utilisation de données écologiques disponibles dans la région indemne. Le Chapitre 1 montre que l'étude de la circulation de pathogènes partageant des caractéristiques éco-épidémiologiques communes (Influenza Aviaire Faiblement Pathogène et Maladie de Newcastle) avec un pathogène émergeant (H5N1 HP) permet d'apporter des éléments d'information sur la circulation potentielle de ce pathogène en cas d'émergence. Les principales conclusions de ce chapitre nous permettent de construire les trois hypothèses testées aux chapitres suivants portant respectivement sur les étapes d'une émergence : introduction (Chapitre 2), circulation (Chapitre 3), et transmission à la faune domestique (Chapitre 4). Ces trois chapitres permettent une meilleure évaluation du risque d'émergence d'un pathogène (le H5N1 HP) dans une zone indemne (le DIN) à partir de méthodes basées sur les données écologiques disponibles dans cette zone indemne et obtenues à partir de techniques telles que le comptage aérien, la télémétrie satellitaire, ou la télédétection. Ils permettent notamment d'estimer que le risque d'émergence du H5N1 HP dans le DIN via l'avifaune sauvage est le plus élevé lors des mois de janvier à mars des années de faible crue, et que la Sarcelle d'été et le canard Pilet sont les deux espèces à surveiller en priorité. Cette thèse montre donc comment l'utilisation de données éco-épidémiologiques disponibles dans une zone indemne permettent une évaluation et un meilleur contrôle du risque d'émergence d'un pathogène. L'utilisation d'outils satellitaires permet l'obtention de larges plages de données ayant des résolutions spatiale et temporelle suffisante pour évaluer des dynamiques éco-épidémiologiques évoluant rapidement
This thesis aims to evaluate the risk of emergence of a pathogen from wildlife in an uninfected area by combining two approaches:1) The study of pathogens sharing similar eco-epidemiological characteristics with the emerging pathogen2) The use of eco-epidemiological data available in the uninfected area Chapter 1 shows that studying pathogens sharing similar eco-epidemiological characteristics (Low Pathogenic Avian Influenza and Newcastle Disease) with an emerging pathogen (HPAI H5N1) enables to provide information on the potential circulation of this pathogen if it would emerge. The main conclusions of this chapter allow us to formulate the three hypothesis tested in the following chapters, each related to a stage of an emergence: introduction (Chapter 2), circulation (Chapter 3), and transmission to domestic poultry (Chapter 4). These three chapters enable a better evaluation of the risk of emergence of a pathogen (HPAI H5N1) in an uninfected area (IND) by using methods based on eco-epidemiological data available in this uninfected area, obtained from techniques like aerial census, satellite telemetry, and remote sensing. The risk of emergence of HPAI H5N1 from wildlife in the IND is evaluated to be the highest between the months of January and March during years with a low flood level. Garganeys and Pintails are identified as the two main species to be surveyed in priority. This thesis shows how eco-epidemiological data available in an uninfected area enable an evaluation and a better control of the risk of emergence of a pathogen. Satellite tools allow acquiring large dataset with temporal and spatial resolution compatible with eco-epidemiological dynamics evolving rapidly

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Jagadesh, Soushieta. "Biogeography of Emerging Infectious Diseases In search for the hotspots of Disease X: A biogeographic approach to mapping the predictive risk of WHO’s Blueprint Priority Diseases Emerging human infectious diseases of aquatic origin: a comparative biogeographic approach using Bayesian spatial modelling Global emergence of Buruli Ulcer Spatial variations between Leishmania species: A biogeographic approach to mapping the distribution of Leishmania species in French Guiana Mapping priority neighborhoods: A novel approach to cluster identification in HIV/AIDS population." Thesis, Guyane, 2020. http://www.theses.fr/2020YANE0007.

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La récente pandémie de Covid19 nous rappelle, si cela était encore nécessaire, que la propagation des maladies infectieuses ignore les frontières géographiques. Les changements combinés de biodiversité locale et l’utilisation des terres, l’augmentation de la connectivité internationale par le transport et le commerce ainsi que la menace imminente du changement climatique a accru le risque d’émergence et de réémergence des maladies infectieuses (EMI). Jusqu’à présent la réponse des politiques de santé publique a été la surveillance passive sans toutefois s’avérer réellement efficace dans la prévention et le contrôle des épidémies. Le choix qui a été fait ici est celui d’une nouvelle approche anticipative, par identification des zones à haut risques d’EMI en se basant sur la détection des facteurs environnementaux les plus favorisant. Parmi ces facteurs on trouve la conversion des terres, la diminution drastique de la biodiversité ou encore le changement climatique. Ainsi la méthode biogéographique a permis d’étudier et d’analyser les EMI à travers différents groupes de taxons de pathogènes comme les bactéries, les virus, les protozoaires et les champignons. L’étude a été portée globalement, ainsi que localement, en Guyane Française, un territoire français d’outre-mer situé en Amérique du Sud. Dans les deux cas, à travers les différents groupes de pathogènes, les risques d’inondation, les récentes conversions de parcelles de forêts en terres agro-minières et l’augmentation du minimum de température due au changement climatique se sont avérés être des facteurs significatifs dans l’émergence globale et locale des maladies infectieuses étudiées. Les principaux résultats de cette thèse sont les suivantes :1. Une approche biogéographique de modélisation de la distribution des EMI en utilisant les bases de données existantes sur les cas cliniques, l’imagerie satellite et un modèle statistique non conventionnel est efficace pour détecter précocement les régions à risque, permettre d’améliorer la prévention, et contrôler leur diffusion.2. Il est possible d’anticiper les EMI en identifiant et en gérant précocement les facteurs favorisant ayant un lien direct avec l’anthropisation de l’environnement
The COVID-19 pandemic highlights that the spread of infectious diseases goes beyond geographical boundaries. Simultaneous changes in local biodiversity and land use, the increasing international connectivity through human transport and trade and the imminent threat of climate change have increased the risk of the emergence and reemergence of infectious diseases. The current public health response to emerging infectious diseases (EID) by passive surveillance has proven largely ineffective in preventing and controlling disease outbreaks. The way toward is to “get ahead of the curve” by identifying potential hotspots of disease emergence and detecting the environmental triggers such as land transformation, biodiversity loss and climate change. I used a biogeographic approach to study and analyze disease emergence across different taxonomic pathogen groups such as bacterial, viral, protozoal and fungal, globally and in French Guiana, a French Overseas territory located in South America. I found that regions at risk of floods, recent conversion of forest to agricultural lands and increasing minimum temperature (i.e. temperature at night) caused by cli mate change were drivers for disease emergence locally and globally across the different pathogen groups. The main findings of the PhD thesis are the following:1. Biogeographic approach to mapping the distribution of EIDs with using existing human cases data, remote sensing imagery and unconventional statistical models is effective to “get ahead of the curve” in the detection of regions at risk and the management of EIDs.2. EIDs are not unprecedented but predictable by identifying and managing the triggers of disease emergence, which have a direct link with the anthropization of the environment

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Hcini, Najeh. "Grossesses à haut risque dans le bassin du Maroni : Conséquences des maladies infectieuses sur la morbi-mortalité maternelle, fœtale et néonatale." Electronic Thesis or Diss., Guyane, 2023. http://www.theses.fr/2023YANE0004.

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Les agents infectieux sont reconnus comme cause de morbi-mortalité maternelle et fœtale. Les nombreuses épidémies qui frappent la Guyane soulignent l’importance de l’exposition de la population guyanaise à la menace infectieuse. Le territoire guyanais est par ailleurs un territoire en pleine croissance avec un fort taux de natalité et qui fait face à des défis majeurs, notamment un taux de prématurité parmi les plus élevés en France et un excès de mortalité infantile. Des questions se posent sur le rôle que pourrait jouer les différentes expositions infectieuses dans ce risque majoré. Afin d’étudier l’étendue des conséquences des pathologies infectieuses chez les femmes enceintes en Guyane, ce travail propose d’étudier l’épidémiologie descriptive et analytique au travers des données d’études réalisées dans la maternité de l’ouest de la Guyane. Son objectif est également de réaliser une analyse du lien entre les différentes expositions infectieuses et le risque majoré des issues défavorables de la grossesse. Pour cela, nous avons conduit des études prospectives non interventionnelles, en suivant un modèle exposé-non exposé, ainsi que d'autres études rétrospectives descriptives impliquant des femmes enceintes exposées à des menaces infectieuses et résidant dans l'ouest guyanais.Ce travail a permis d’identifier le jeune âge, la nulliparité et la précarité sociale comme des facteurs de risque majeurs de survenue des infections pendant la grossesse. Nous avons pu confirmer le risque majoré de prématurité, de perte fœtale et de naissance par césarienne au sein de la population des mères ayant eu de la fièvre comparativement à celles ne l’ayant pas eu. Nous avons confirmé l’effet tératogène du virus Zika et du virus Tonate. En effet, nous avons décrit le premier cas de transmission verticale du virus Tonate associé à des malformations multiples chez un fœtus. De plus, nous avons démontré la relation entre l’infection fœtale au Virus Zika et un retard des acquisitions neurologiques et neurosensorielles du fœtus, du nouveau-né et des enfants jusqu’à l’âge de 3 ans. En 2020, la première vague de Covid 19 a été particulièrement intense et a conduit dans notre population à un surrisque d’hémorragie du post-partum, de transfusion et d'admission en unité de soins intensifs dans la population des femmes infectées comparativement à celles non infectées. Elle a conduit également à un risque plus élevé de pertes fœtales. La précarité et les modifications du système de soins pendant l’épidémie auraient joué un rôle indirect. Les épidémies sont parfois associées, ainsi en 2020, il coexistait l’épidémie COVID 19, une épidémie de dengue ainsi qu’une augmentation des cas de syphilis. Nous avons rapporté une augmentation du nombre des cas de syphilis chez les femmes enceintes aboutissant à une véritable épidémie de syphilis dans l’ouest. Plus de la moitié des femmes enceintes infectées non traitées risque d’avoir une issue défavorable de leurs grossesses, incluant les naissances prématurées, les morts fœtales in utéro ou les morts périnatales ou encore des cas de syphilis congénitale pouvant entraîner des séquelles à distance. Ainsi, les agents infectieux sont une cause importante de morbi-mortalité néonatale en Guyane et nécessitent une surveillance particulière. Ils représentent au moins 4% des causes directes de mort fœtale sur le territoire. Les retombées de ces travaux sont majeures. Elles vont aider à optimiser le dépistage, le bilan initial, identifier les facteurs de risque aggravants, guider la prise en charge thérapeutique et la surveillance des infections chez les jeunes mères guyanaises pour réduire la morbi-mortalité maternelle et fœtale associée
Infectious agents are recognized as a cause of maternal and fetal morbidity and mortality. The numerous infectious epidemics that have occurred in French Guiana reveal the exposure of the population to numerous pathogens. French Guiana is experiencing rapid growth and boasts one of the highest birth rates in France. Studies confirm that infant mortality remains high, and premature births are among the highest in France. Many questions arise regarding the impact of various infectious epidemics and their role in this increased risk. To study the extent and consequences of infectious diseases in pregnant women in western French Guiana, this work aimed to study the descriptive and analytical epidemiology through scientific data from the western French Guiana maternity. It will also analyze the link between different infectious exposures and the increased risk of maternal and neonatal adverse outcomes. To achieve our objectives, we conducted non-interventional prospective studies, following an exposed-unexposed model, as well as other retrospective descriptive studies involving pregnant women exposed to infectious threats and residing in Western French Guiana.According to the results of our research, we found that young age, nulliparity, and social precarity are major risk factors for infections during pregnancy. We confirmed the link between exposure to fever during pregnancy and the increased risk of prematurity, fetal loss, and delivery by cesarean section in the population of mothers who experienced a fever, compared to those who did not. We have confirmed the teratogenic potential of the Zika virus and the Tonate virus. In fact, we have described the first case of vertical transmission of the Tonate virus and its associated fetal birth defects. Furthermore, we have demonstrated the relationship between Zika virus infection and delayed neurological and neurosensory development in fetuses, newborns, and children up to the age of 3. In 2020, the first wave of COVID-19 was particularly intense and led to a higher risk of postpartum hemorrhage, transfusion, and admission to intensive care units in the population of infected women compared to those who were not infected. It also led to a higher risk of fetal adverse outcomes. Social precarity and changes in the healthcare system during the epidemic may have played an indirect role. Epidemics are sometimes associated, as in 2020, the COVID-19 epidemic, a dengue epidemic, and an increase in syphilis cases coexisted. We have reported an increase in the number of syphilis cases among pregnant women, resulting in a true syphilis epidemic in the west. More than half of non-treated pregnant women will have an unfavorable pregnancy outcome. Syphilis infection is associated with an increased risk of prematurity, intrauterine fetal death, perinatal death, and congenital syphilis with a risk of long-term sequelae.Thus, infectious agents are a significant cause of fetal and neonatal morbidity and mortality in French Guiana and require special monitoring. It represents at least 4% of direct causes of fetal loss in the territory. The outcomes of this work are significant. They will certainly help optimize screening, initial assessment, identify exacerbating risk factors, guide therapeutic management, and monitor infections in mothers to reduce maternal and fetal morbidity and mortality resulting from these infections

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Carolan, Kevin. "Ecological niche modelling and its application to environmentally acquired diseases, the case of Mycobacterium ulcerans and the Buruli ulcer." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20178/document.

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L'ulcère de Buruli est une maladie émergente tropicale négligée. Il provoque une défiguration et une incapacité permanente pour les victimes. L'agent causal est Mycobacterium ulcerans. Cependant, le réservoir environnemental et le mode de transmission de cette bactérie ne sont pas connus. Les tentatives visant à gérer la maladie ont été freinées par le manque de connaissances concernant le mode de transmission ainsi que le réservoir environnemental de M. ulcerans. Certains écosystèmes et habitats ont été associés au risque de contracter cette mycobactérie, notamment les milieux aquatiques d'eau douce stagnants et perturbés par les activités humaines des régions tropicales. S'il n'existe pas de vecteur bien identifié, des insectes aquatiques Hémiptères sont fortement suspectés d'intervenir dans la vectorisation de cet agent infectieux à l'humain. Une compréhension complète de la distribution et du mode de transmission de la bactérie aiderait ainsi à la gestion de la maladie. Dans cette thèse, nous utilisons les outils issus de la modélisation de la niche écologique pour décrire la distribution de M. ulcerans. Suite à la construction d'un modèle au Cameroun, en Afrique Centrale, et testé avec une seconde base de données en Guyane Française (Amérique du Sud), nous trouvons que l'agent pathogène montre des variations saisonnières notables dans la répartition de nos sites d'étude, au Cameroun. Pendant la saison humide, M. ulcerans est plus fréquente dans les grands bassins versants et en absence de marécages, tandis que durant la saison sèche, la bactérie est plus présente dans les petits bassins versants où peuvent être présents dans les zones marécageuses. Notre étude a permis de générer des cartes de répartition de l'agent pathogène dans la région d'étude, qui pourront être utilisées dans des études ultérieures contribuant à mieux gérer le risque infectieux pour cette maladie. De plus, nous avons développé une modélisation des niches écologiques des insectes aquatiques soupçonnés d'être des vecteurs de l'agent pathogène. Basé sur un protocole d'échantillonnage d'insectes aquatiques qui couvre l'ensemble du Cameroun, nous avons construit un modèle suivant la méthode de l'entropie maximale. Ceci nous a permis d'interpoler notre modèle sur toute l'Afrique de l'Ouest. Nous avons ensuite testé une corrélation entre la répartition prévue des insectes potentiellement vecteurs, et la prévalence de l'ulcère de Buruli. Nous mettons en évidence une corrélation positive significative entre la répartition des insectes et la répartition de la maladie, et trouvons que cette corrélation varie significativement dans l'espace et le temps. Ceci est cohérent avec la possibilité d'une transmission multi-hôte pour cet agent pathogène.Enfin, en collaboration avec d'autres auteurs, nous avons pu explorer différents facteurs influençant la distribution de M. ulcerans, tels que les réseaux et la structure de la communauté biotique, ou encore l'impact de l'occupation du sol sur la distribution de l'ulcère de Buruli dans notre région d'étude d'Akonolinga au Cameroun. Et enfin nous avons testé le changement de distribution de la maladie à une plus grande échelle, entre le Bénin et le Nigeria. Cette thèse contribue à une meilleure compréhension de la distribution de Mycobacterium ulcerans et de l'ulcère de Buruli, fournissant des éléments de preuve d'une transmission multi-hôtes de la mycobactérie, ainsi que les premières cartes de répartition de l'agent pathogène pour la région d'Akonolinga au Cameroun
The Buruli ulcer is an emerging environmentally acquired infectious neglected tropical disease. It causes permanent disability and disfigurement in victims. The causative agent is Mycobacterium ulcerans; however the environmental reservoir and mode of transmission of this bacterium are not known. Attempts to manage the disease have been hampered by lack of knowledge of the mode of transmission and the environmental reservoir of M. ulcerans. Certain environments have been associated with the disease, notably disturbed aquatic environments composed of small bodies of stagnant water. There is no known vector, though aquatic insects have been implicated as possible vectors. A full understanding of the distribution and mode of transmission of the bacterium would help in management of the disease.In this thesis, we use the tools developed in ecological niche modelling to describe the distribution of M. ulcerans. Following the construction of a model in Cameroon, Central Africa, and tested against a second database in French Guiana (South America), the pathogen is found to have notable seasonal changes in its distribution in our study sites in Cameroon. In the wet season, M. ulcerans is more common in large watersheds, while in the dry season the bacterium is more common in small watersheds. This enabled the generation of hazard maps of the pathogen distribution in the study region, which will be used in future studies and management of the disease. Following this we undertook ecological niche modelling to describe the distribution of the aquatic insects suspected to be vectors of M. ulcerans. Based on a sampling protocol that spanned the country of Cameroon, we undertake maximum entropy modelling, which enabled us to interpolate our model across all of West Africa. With these maps we explore the correlation between the predicted distribution of the insects to the prevalence of the Buruli ulcer. We find a significant positive correlation between the distribution of the insects and the distribution of the disease, and find that this correlation undergoes significant changes in space and time, consistent with the model of multi-vectorial transmission of the disease.Finally, in collaboration with other authors, we have assisted in exploring how the distribution of M. ulcerans changes according to community structure networks, how the distribution of the Buruli ulcer disease changes in our study region of Akonolinga, Cameroon, and how the distribution of the disease changes at a larger scale, between Benin and Nigeria. This thesis contributes to our understanding of the distribution and drivers of Mycobacterium ulcerans and the Buruli ulcer, providing evidence of multi-vectorial transmission of the disease, and the first hazard maps of the pathogen for Akonolinga, Cameroon

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Golding, Nicholas. "Mapping and understanding the distributions of potential vector mosquitoes in the UK : new methods and applications." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:6ae52a0a-2aaa-42d6-a57a-e3879ad559d8.

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A number of emerging vector-borne diseases have the potential to be transmitted in the UK by native mosquitoes. Human infection by some of these diseases requires the presence of communities of multiple vector mosquito species. Mitigating the risk posed by these diseases requires an understanding of the spatial distributions of the UK mosquito fauna. Little empirical data is available from which to determine the distributions of mosquito species in the UK. Identifying areas at risk from mosquito-borne disease therefore requires statistical modelling to investigate and predict mosquito distributions. This thesis investigates the distributions of potential vector mosquitoes in the UK at landscape to national scales. A number of new methodological approaches for species distri- bution modelling are developed. These methods are then used to map and understand the distributions of mosquito communities with the potential to transmit diseases to humans. Chapter 2 reports the establishment of substantial populations of the West Nile virus (WNV) vector mosquito Culex modestus in wetlands in southern England. This represents a drastic shift in the species’ known range and an increase in the risk of WNV transmission where Cx. modestus is present. Chapter 3 develops and applies a new species interaction distribution model which identifies fish and ditch shrimp of the genus Palaemonetes as predators which may restrict the distribution of the potential WNV vector community in these wetlands. Chapter 4 develops a number of methods to make robust predictions of the probability of presence of a species from presence-only data, by eliciting and applying estimates of the species’ prevalence. Chapter 5 introduces a new Bayesian species distribution modelling approach which outperforms existing methods and has number of useful features for dealing with poor- quality data. Chapter 6 applies methods developed in the previous two chapters to produce the first high-resolution distribution maps of potential vector mosquitoes in the UK. These maps identify several wetland areas where vector communities exist which could maintain WNV transmission in birds and transmit it to humans. This thesis makes significant contributions to our understanding of the distributions of UK mosquito species. It also provides methods for species distribution modelling which could be widely applied in ecology and epidemiology.

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Myers, Kendall Page. "Zoonotic influenza and occupational risk factors in agricultural workers." Diss., University of Iowa, 2007. http://ir.uiowa.edu/etd/221.

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Beadell, Jon Sumner. "Emerging infectious disease host and parasite perspectives /." College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/6744.

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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.
Thesis research directed by: Biology. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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Wombwell, Emma Louise. "Emerging infectious disease and the trade in amphibians." Thesis, University of Kent, 2014. https://kar.kent.ac.uk/48014/.

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Amphibians are the most threatened class of vertebrate, and rates of species decline and extinction far exceed those seen historically. Habitat loss, climate change, over-exploitation and emerging infectious disease have all been identified as threatening processes. The trade in amphibians has been implicated in over-exploitation through the harvesting of wild animals, and as an important pathway for the global spread of the fungal pathogen, Batrachochytrium dendrobatidis (Bd). However, there are no analyses of how Bd may spread through the trade chain. This thesis addresses this issue by (1) determining the prevalence of Bd at different stages of the trade chain; (2) examining knowledge, husbandry protocols and biosecurity among retailers and (3) assessing the risk of Bd dissemination into the wild in the UK. Approximately 20,000 amphibians from at least 11 countries enter the UK annually via Heathrow Animal Reception Centre. Overall Bd prevalence was 3.6%, but was confined to six of the 43 genera encountered, and only detected in shipments from the USA and Tanzania. Amphibians were sold by 30% of the estimated 3500 livestock retailers in the UK, but made a low contribution to overall income. Disease awareness and knowledge in retailers was found to be lacking, although husbandry standards were deemed to be appropriate. Mortality appeared to be influenced by restocking methods and number of species held, but mass die-offs as a result of disease were generally uncommon. Screening of over 2000 amphibians from 148 retailers for Bd revealed a prevalence of 5.8%, but the geographic distribution of infection in the UK was patchy, and was more prominent in aquatic species. A risk assessment conducted according to the framework set out by the World Organisation of Animal Health, identified regions and sections of the trade that pose the greatest threats in terms of introducing Bd, and assessed various mitigation measures. The consequences of novel strains of Bd and a second, recently discovered Batrachochytrium species were found to pose a risk to both native UK and captive amphibians. As trade bans are unlikely to be feasible or effective, alternative measures to mitigate the impact of disease are evaluated.

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Altmann, Mathias. "Détection, investigation et contrôle des maladies émergentes. Expériences en santé mondiale." Thesis, Bordeaux, 2022. http://www.theses.fr/2022BORD0217.

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Contexte : l'émergence de maladies infectieuses est la conséquence de déséquilibres dynamiques, au sein d'écosystèmes complexes distribués à une échelle géographique donnée comprenant des humains, des animaux, des agents pathogènes et l’environnement. La mondialisation croissante des échanges implique une augmentation des flux internationaux de voyageurs et de marchandises qui peut favoriser la propagation des maladies infectieuses. Dorénavant, une crise sanitaire dans une région ou un pays peut avoir des répercussions très rapides sur la santé et l’économie dans de nombreuses parties du monde. Détecter les émergences, les comprendre par des investigations de terrain sont des étapes indispensables pour mieux contrôler les futures épidémies et pandémies. Expériences : au cours de mon parcours professionnel, mon travail personnel m’a permis d’aborder ces trois dimensions au travers de trois études qui ont donné lieu à publication dans des revues internationales à comité de lecture. Etude 1) Au cours d’une épidémie nationale d’Escherichia Coli O104 :H4 en 2011, j’ai exploré la rapidité du système de surveillance allemand en matière de détection, et recommandé une révision du système de surveillance en organisant la notification par les médecins et chefs de laboratoires dans une base de données centralisée et partagée avec différents droits d'accès par les services de santé aux niveau local, régional et national. Etude 2) Au décours de la pandémie grippale en 2009, j’ai investigué et comparé les caractéristiques des cas sévères pédiatriques en Allemagne durant deux saisons. La gravité inchangée de la grippe A(H1N1)pdm09 au cours de la première saison post pandémique (2010-11) et la proportion élevée et constante d'infections possiblement acquises à l'hôpital ont souligné le défi de prévenir les cas pédiatriques au-delà de la situation pandémique. Etude 3) Lors de l’épidémie du virus Ebola (MVE) en 2014, j’ai évalué les performances du contact tracing au Libéria en tant que mesure de contrôle spécifique. Malgré l'ampleur sans précédent du contact tracing pour la MVE au Libéria, sa capacité à détecter de nouveaux cas était limitée, en particulier dans les zones urbaines et pendant le pic épidémique. Discussion : la pandémie de Covid-19 a révélé des faiblesses des systèmes de surveillance dans presque tous les pays. Les leçons apprises au cours des épidémies et pandémies précédentes telles que celles auxquelles j’avais été exposé professionnellement et que je rapporte ici ont été insuffisamment prise en considération. En Afrique, les estimations de l’incidence et de la mortalité sont respectivement 100 fois et 15 fois plus élevées que les notifications. Parmi les explications à ces différences très importantes, on doit citer la faiblesse des systèmes de surveillance, du suivi des contacts, de l’utilisation des tests de dépistage et de diagnostic et le manque d’accès aux soins. L’amélioration des systèmes de surveillance des maladies émergentes nécessite : 1) d’accélérer la digitalisation et la mise en réseau des systèmes d’information sanitaire à tous les niveaux, des centres de santé et laboratoires périphériques jusqu’à l’échelon international ; 2) la captation, l’utilisation effective et la mise en relation d’autres sources de données (communautaires, enregistrements des décès, données animales et environnementales) et l’utilisation régulée d’internet et des réseaux sociaux ; 3) de renforcer les compétences et l’expertise des épidémiologistes de terrain et leur mise en réseau ; 4) d’investir dans la recherche au cours et entre les épidémies ; et 5) que les bailleurs de fonds et les gouvernements reconnaissent le caractère inévitable des prochaines épidémies de maladies infectieuses ou autres, aux conséquences graves, notre vulnérabilité à celles-ci et la nécessité d’investir en santé mondiale
Context: the emergence of infectious diseases is the consequence of dynamic imbalances, within complex ecosystems distributed at a given geographical scale including humans, animals, pathogens and the environment. The increasing globalization of trade implies an increase in international flows of travelers and goods which can promote the spread of infectious diseases. From now on, a health crisis in one region or country can have very rapid repercussions on health and the economy in many parts of the world. Detecting emergences and understanding them through field investigations are essential steps to better control future epidemics and pandemics. Experience: during my professional career, my own work has allowed me to address these three dimensions through three studies that have resulted in publications in international peer-reviewed journals. Study 1) During a nationwide outbreak of Escherichia Coli O104:H4 in 2011, I explored the timeliness of the German surveillance system for detection, and recommended a review of the surveillance system by organizing reporting by doctors and heads of laboratories in a centralized and shared database with different access rights by health services at local, regional and national level. Study 2) Following the influenza pandemic in 2009, I investigated and compared the characteristics of severe pediatric cases in Germany during two epidemic seasons. The unchanged severity of influenza A(H1N1)pdm09 during the first post-pandemic season (2010-11) and the consistently high proportion of possibly hospital-acquired infections highlighted the challenge of preventing pediatric cases beyond the pandemic situation. Study 3) During the Ebola virus (EVD) outbreak in 2014, I evaluated the performance of contact tracing in Liberia as a specific control measure. Despite the unprecedented scale of contact tracing for EVD in Liberia, its ability to detect new cases was limited, especially in urban areas and during the epidemic peak. Discussion: the Covid-19 pandemic has revealed weaknesses in surveillance systems in almost all countries. Lessons learned during previous epidemics and pandemics such as those to which I had been exposed professionally and which I report here have been insufficiently considered. In Africa, estimates of incidence and mortality are respectively 100 times and 15 times higher than official reports. Explanations for these very large differences include weak surveillance systems, insufficient use of contact tracing, screening and diagnostic tests, and lack of access to care. Improving surveillance systems for emerging diseases requires: 1) accelerating the digitization and networking of health information systems at all levels, from health centers and peripheral laboratories to the international level; 2) the capture, effective use and linking of other data sources (communitybased, death registries, animal and environmental data) and the regulated use of the internet and social networks; 3) to strengthen the skills and expertise of field epidemiologists and their networking; 4) to invest in research during and between epidemics; and 5) that donors and governments recognize the inevitability of future epidemics of infectious and other disease conditions with serious consequences, our vulnerability to them and the need to invest in global health

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Baudouin, Alice. "Rôles relatifs des facteurs démographiques, sociaux et sélectifs sur la sélection de partenaires reproducteurs chez le gorille des plaines de l'ouest." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1B057/document.

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Chez de nombreuses espèces, il a été montré que les stratégies de choix de partenaires socio-sexuels par un individu étaient liées aux qualités de ces partenaires (phénotypiques ou génétiques) et étaient susceptibles de maximiser la qualité de ses descendants et améliorer sa propre valeur adaptative. Nous nous sommes intéressés au choix de partenaires chez les femelles de gorille de plaines de l’ouest par une étude de leur dispersion sociale en lien avec l’influence relative de l’environnement social et des caractéristiques des mâles adultes dans les décisions des femelles à résider dans un groupe social ou à émigrer, et dans leur choix du groupe dans lequel immigrer. Nous avons montré que les femelles immigrent préférentiellement dans des groupes reproducteurs plutôt que vers des mâles solitaires et vers des groupes jeunes plutôt que vieillissants. Les groupes de 10-15 individus sont évités. Les femelles émigrent des groupes contenant une grande proportion d’individus affectés par une maladie de peau. A court terme après un effondrement démographique du à une épidémie à virus Ebola, le taux d’émigration des femelles diminue dans les groupes de grande taille, ce qui suggère une meilleure qualité reproductrice et protectrice des mâles survivants. Les caractéristiques génétiques des partenaires sexuels dans le choix des femelles, notamment les gènes du complexe majeur d’histocompatibilité (CMH) qui codent pour des protéines impliquées dans les défenses immunitaires, peuvent être impliquées dans le choix de partenaire chez certains primates. Son implication éventuelle n’avait jamais été étudiée chez le gorille. Dans cette perspective nous avons cherché à développer une méthode pour étudier ce complexe de gènes à partir d’échantillons d’ADN non invasifs (fèces), c’est-à-dire avec de l’ADN faiblement concentré et dégradé. Nous avons défini une nouvelle amorce puis utilisé des méthodes de séquençage haut débit, d’électrophorèse sur gel à gradient dénaturant et un marqueur microsatellite lié au CMH afin de déterminer une méthode d’analyse à l’échelle populationnelle. Huit nouveaux allèles de CMH ont été détectés par séquençage haut débit. Le marqueur microsatellite présente un schéma d’amplification complexe et nécessite une optimisation des protocoles qui permettra de réduire les couts d’analyses de la variabilité du CMH à l’échelle populationnelle. Nos développements ouvrent de nouvelles perspectives pour l’étude de l’influence du CMH sur le choix de partenaire dans des populations sauvages de primates
In many species, it has been shown that strategies of choice of socio-sexual partners by an individual are related to the phenotypic or genetic quality of these partners and are likely to maximize the quality of its descendants and improve its own fitness. We investigated the partner choice in western lowland gorilla females in studying their social dispersion and the relative influence of the social environment and the characteristics of adult males in females’ decisions, to stay in a social group or to emigrate, and in their choice of the group into which immigrate. We showed that females preferentially migrated towards breeding groups rather than solitary males and towards younger rather than aging groups. Groups of 10-15 individuals were avoided. Females emigrated from groups containing a large proportion of individuals affected by skin disease. In the short term after a demographic die-off due to an Ebola epidemic, female’s emigration rates declined in large groups, suggesting better reproductive and protective value of surviving males. The influence of the genetic characteristics of the sexual partners in the choice of females, in particular the genes of the major histocompatibility complex (MHC) genes that encode proteins involved in immune defenses, may be involved in partner choice in some primates. Its possible involvement had never been studied in the gorilla. In this perspective we have sought to develop a method to study this gene complex from non-invasive DNA samples (feces), that is to say with weakly concentrated and degraded DNA. We defined a new primer and then used high throughput sequencing, denaturing gradient gel electrophoresis, and a MHC-linked microsatellite marker to determine a population-level analysis method. Eight new MHC alleles were detected by high throughput sequencing. The microsatellite marker has a complex amplification pattern and requires protocol optimization that will reduce the cost of analyzing MHC variability at the population level. Our developments open new perspectives for the study of the influence of CMH on partner choice in wild populations of primates

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Reis, António Maria Malta do Carmo. "O contributo da saúde animal no acesso aos mercados, na segurança alimentar global e na luta contra a fome." Bachelor's thesis, Universidade Técnica de Lisboa. Faculdade de Medicina Veterinária, 2011. http://hdl.handle.net/10400.5/3507.

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Dissertação de Mestrado Integrado em Medicina Veterinária
No Século XXI continuam presentes doenças como o HIV/Sida, a Malária, a vCJD, a Raiva ou o Síndrome Respiratório Agudo Grave. Estas doenças têm em comum, o facto de serem consideradas Doenças Infecciosas Emergentes (DIE). A maioria das DIE são zoonoses (60,3%) sendo que 71,8% têm origem na fauna selvagem. O conceito “Uma Saúde” ganhou uma relevância enorme na compreensão dos factores que estão na origem da emergência e da reemergência sem precedentes das DIE. Nestes factores incluem-se a globalização das viagens e do comércio internacional, as alterações climáticas, o insucesso das medidas de Saúde Pública e o bioterrorismo. Nas últimas décadas, a maioria das DIE ocorreram nos países em desenvolvimento e tiveram impactos graves principalmente nas populações pobres que dependem do gado (70%). Paradoxalmente, nos países em desenvolvimento, o volume de carne e leite produzido ultrapassou há muito a produção realizada nos países desenvolvidos e prevê-se que devido ao crescimento da população mundial e às alterações nos hábitos e preferências alimentares, a procura global de carne e leite aumente cerca de 55%. A maior quota ocorrerá nos países em desenvolvimento, nos quais se prevê que a procura aumente cerca de 95% na carne e de 80% no leite, sendo estes os países com piores índices de Segurança Alimentar e os mais afectados pela fome e pela pobreza. Neste contexto as ocorrências de DIE e a necessidade de aumentar o aporte de proteína de origem animal, demonstram a urgência de reforçar e melhorar a qualidade dos Serviços Veterinários, principalmente nos países em desenvolvimento. Esta dissertação é o resultado do estágio curricular efectuado na Organização Mundial de Saúde Animal (OIE), do trabalho realizado no Programa EDES e de uma pesquisa bibliográfica neste âmbito. Pretende descrever como as DIE e os factores de risco que as determinam podem condicionar o aumento da produção de proteína de origem animal e analisar o contributo da OIE e dos serviços veterinários - no acesso aos mercados, na Segurança Alimentar, no combate à fome e na redução da pobreza – através do impacto da aplicação das normas sanitárias internacionais.
ABSTRACT - The animal health contribution to market access, food security and global fight against hunger - In the XXI Century diseases such as HIV/AIDS, Malaria, vCJD, Rabies and Severe Acute Respiratory Syndrome remain present. These diseases have in common the fact that they are Emerging Infectious Diseases (EID). The majority of EID are zoonoses (60.3%) of which 71.8% originated in wildlife. The One Health concept has gained great relevance in understanding the factors that promote the unprecedented emergence and reemergence of EID. These include factors such as the global scale of international trade and travel, climate change, breakdown in public health or control measures and bioterrorism. In the last decades, most EID have occurred in developing countries and have had a serious impact especially on the world’s poor livestock farmers (70%). On the other hand, the volume of meat and milk produced in these countries outpaced the production in developed countries and further more it is expected that the global demand for milk and meat will increase »55%, due to the world population growth and change in eating habits. The largest share of this increase will occur in developing countries, where demand increases of 95% for meat and 80% for milk are expected. However, these countries have the highest level of food insecurity and a stick seriously affected by hunger and poverty. Due to issues caused by EID outbreaks and the need for animal protein intake, there is an urgent need to strengthen and improve the quality of veterinary services, in particularly in developing countries. This dissertation is the output of an internship done at the World Organisation for Animal Health (OIE), the work performed with the EDES Programme and a bibliography research. It aims to highlight how EID and determinant risk factors, might influence the increased production of animal protein and to analyze the contribution of OIE and of Veterinary Services to market access, food security, poverty reduction and the global fight against hunger, through the impact of the application of international sanitary measures standards set by the OIE.

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Rojek, Amanda. "Improving patient centred research during infectious disease outbreaks." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:8a53052f-9585-4709-a06e-15586826efce.

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Emerging infectious diseases (EIDs) constitute an important global health security problem. During EID outbreaks, patient centred research can play a significant role in informing evidence-based care for patients, in calibrating public health responses, and in directing effective policy and research. However, to date, this type of research has been limited in impact. This thesis sets out to improve the value of patient centred research in combating EID outbreaks. It provides a structured analysis of what has previously constrained efforts to rapidly accumulate high-quality evidence. It provides primary data from research conducted during an outbreak, and conducted in an outbreak vulnerable setting. And it provides recommendations that aim to facilitate high-quality data collection in future events. This thesis contains four results chapters. Chapter 2 systematically reviews elements of the research response to two EID outbreaks of public health importance. Chapter 3 provides findings of a phase II clinical trial of an investigational therapy for Ebola virus disease (EVD), contextualises the utility of this and comparable work in improving patient care, and discusses the operational feasibility of such work during an epidemic. Chapter 4 focuses specifically on improving one element - disease characterisation - during EID outbreaks. It achieves this through presenting a systematic analysis of bias in the characterisation of EVD and recommends how to prioritise data gathering for high-risk pathogens. Chapter 5 exemplifies how clinical data collection practices can progress between outbreaks. It is the first stage of work undertaken to improve the clinical characterisation of communicable diseases in the vulnerable environment of refugee camps. This thesis demonstrates progress towards having higher quality clinical research conducted during the time frame of an epidemic. Future work can focus on the most important barriers to accelerating research, now that these have been more clearly defined.

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Cohen, Jeremy. "Climate Change Drives Outbreaks of Emerging Infectious Disease and Phenological Shifts." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6483.

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Climate change is expected to impact species by altering infectious disease outcomes, modifying community composition, and causing species to shift their phenology, body sizes and range distributions. However, the outcomes of these impacts are often controversial; for example, scientists have debated whether climate change will exacerbate emerging infectious disease and which species are at greatest risk to advance their phenology. There reason for these controversies may be that climate change is impacting diverse processes across a wide range of ecological scales, as the interplay between fine-scale processes and broad-scale dynamics can often cause unpredictable changes to the biosphere. Therefore, it is important to consider how ecological processes change across spatial, temporal and allometric scales in order to understand the impacts of climate change. For example, if community composition controls disease distributions at small spatial scales while abiotic factors do so at large, regional scales, studies conducted at a single spatial scale may misestimate the impacts of climate change on biodiversity. Because small organisms acclimate quickly, they may track their phenology to climatic factors over shorter temporal scales than large organisms. In addition, small organisms have wider thermal breadths, or temperature ranges where performance is relatively strong, than large organisms. This may cause cold-adapted hosts to face performance gaps with parasites at warmer temperatures than those where host or parasite performance peaks, putting them at risk when the climate warms. I began my dissertation work by examining how spatial scale modulates the observed effects of human modifications to ecological processes. Humans are altering the distribution of species by changing the climate and disrupting biotic interactions and dispersal. A fundamental hypothesis in spatial ecology suggests that these effects are scale-dependent; biotic interactions should shape distributions at local scales while climate should control them at regional scales. Thus, common single-scale analyses might be unable to accurately estimate the impacts of anthropogenic modifications on biodiversity and the environment because they may miss effects at other scales. However, the large-scale datasets and computing power necessary to test scale hypotheses have not been available until recently. I conducted a cross-continental, cross-scale (almost five orders of magnitude) analysis of the influence of biotic, abiotic, and dispersal processes on the distribution of three emerging pathogens: the amphibian chytrid fungus implicated in worldwide amphibian declines, and West Nile virus and the bacterium that causes Lyme disease (Borrelia burgdorferi), which are responsible for ongoing human health crises. For all three pathogens, biotic factors were only significant predictors of distributions at local scales (~102-103 km2), whereas climate factors and a proxy for dispersal limitations were almost always only significant at relatively larger, regional scales (>104 km2). Spatial autocorrelation analyses revealed that biotic factors were relatively more variable at smaller scales whereas climatic factors were more variable at larger scales, consistent with the prediction that factors should be important at the scales they vary the most. Finally, no single scale could detect the importance of all three categories of processes. My results highlight that common, single-scale analyses can misrepresent the true impact of anthropogenic modifications on biodiversity and the environment. Although it is important to understand how ecological processes affect patterns across scales, a critical step towards understanding the ecological impacts of climate change is to develop cross-scale frameworks that can predict these patterns. Thus, I proceeded to develop a framework to help understand how species are altering their phenology, or the timing of seasonal activities, using data collected across spatial and temporal scales. Phenological shifts are concerning because they can cause species declines by creating asynchronies or “mismatches” in plant–pollinator, plant–herbivore, and host–parasite interactions. Although advancements in the phenology of plants and animals have been widely reported and synthesized, several open knowledge gaps of critical concern have persisted. First, although many phenological studies and syntheses assume climate change as an important driver of phenological shifts, many do so without explicitly testing for any effect of climate, and among those that have, standardized climate data are rarely used. As a consequence, it remains unclear which climatic variables are driving shifts in phenology and whether geographical heterogeneity in these variables across regional scales has impacted their predictive power to detect ecological trends. Second, one of the chief concerns about species shifting the timing of their phenologies is the possibly of ecological mismatches, or asynchrony in the timing of species interactions, especially in mutualisms. I hypothesized that across regional scales, factors driving seasonality would also drive phenological shifts. I also hypothesized that small species might shift their phenology faster than large organisms because they acclimate to new conditions more easily. I addressed these questions by synthesizing 1,011 published time series of animal phenology and historic global climate data using a meta-analytical framework. I found that while temperature drives phenological responses at high latitudes, low-latitude shifts are driven by precipitation. Small body size and ectothermy were associated with strong phenological shifts, suggesting emerging asynchrony between hosts and parasites and predators and prey. Finally, I looked at how variation across allometric scales might impact host-parasite interactions in the context of changing temperatures. Small organisms have larger performance breadths, or temperature ranges where performance is relatively high, than large organisms, and thus pathogens should typically have broader performance breadths than hosts. Therefore, the performance gap between pathogens and cold- and warm-adapted hosts should occur at relatively warm and cold temperatures, respectively. To test this hypothesis, which I coin the thermal mismatch hypothesis, we quantified the temperature-dependent susceptibility of “cold-“ and “warm-adapted” amphibian species (Atelopus zeteki, Osteopilus septentrionalis, and Anaxyrus terrestris) to the fungal pathogen Batrachochytrium dendrobatidis (Bd) using laboratory experiments and field prevalence estimates from 4,775 host populations. In both the laboratory and field, I found that peak susceptibility for cold- and warm-adapted hosts occurred at relatively warm and cool temperatures, respectively, providing support for the thermal mismatch hypothesis. Finally, I found that the temperature-dependent A. zeteki mortality patterns observed in our experiment accurately predicted historic extinctions of Atelopus spp., suggesting that climate change contributed to the extinctions. My results suggest that as climate change shifts hosts away from their optimal temperatures, the probability of infectious disease outbreaks may increase, but the effect will depend on the host species and the direction of the climate shift. My findings partly explain the tremendous variation in species’ responses to climate change. Based on the results of my dissertation, I conclude that climate change has diverse effects on ecology across scales. Biotic interactions control disease distributions at small, local spatial scales while abiotic factors do at large scales, suggesting that climate change may impact species distributions differently at different scales. Across temporal scales, differences in acclimation rates could be affecting which species are more likely to shift their phenology. Finally, across allometric scales, differences in thermal breadths between individuals of different body sizes could alter host-parasite interactions by causing hosts to be susceptible to disease even at conditions far from where parasites perform best. Thus, I believe that my dissertation has contributed to what we understand about how scale relates to disease and biodiversity declines in the context of climate change.

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Roure, i. Díez Sílvia. "Malalties infeccioses emergents a la zona Metropolitana Nord de Barcelona." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/383032.

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Els canvis socioeconòmics i climàtics, que pateix el món globalitzat condueixen a un canvi d’escenari de la patologia infecciosa que s’atén en l’àmbit sanitari i que requerirà una especialització i expertesa que intentem reflectir en aquest treball. La present tesi estudia i analitza dades sanitàries de la població viatgera i immigrant establerta a la zona Metropolitana Nord de Barcelona, majoritàriament de la comunitat resident a Badalona i a Santa Coloma de Gramenet durant el període fonamentalment 2007 al 2013. La majoria de dades s’han recollit tan a nivell de l’atenció primària (Unitat de Salut Internacional Metropolitana Nord) com a nivell d’un hospital de tercer nivell (Hospital Germans Trias i Pujol), ambdós conformant la Unitat territorial de Salut Internacional Metropolitana Nord del Programa de Salut Internacional de l’ Institut Català de la Salut (PROSICS) aprovat al 2012. La tesi s’ha dividit en quatre treballs que responen a quatre premisses: 1. A 5 anys de la crisi econòmica existeix una variació en el perfil de risc del viatger internacional que es desplaça per motiu laboral. N’ha augmentat el número, així com els factors de risc als que s’exposa per adquirir malalties infeccioses 2. La incidència de dengue i chikungunya està en augment en l’àrea Metropolitana Nord de Barcelona a expenses de casos importats per viatgers internacionals. Malgrat que fins al moment no ha aparegut cap cas autòcton la zona està densament poblada pel vector Ae.albopictus. 3. Un 90% dels casos de infeccions per Strongyloides stercolaris que es diagnostiquen a la nostra zona són importades per immigrants. Majoritàriament es tracta de infeccions asimptomàtiques i el diagnòstic es basa en la sospita clínica i/o analítica, i en la cerca activa del paràsit. Caldrà implementar protocols de cribatge en immigrants immunodeprimits per l’alta mortalitat que pot comportar la reactivació de la infecció. 4. La malaltia de Chagas és la malaltia emergent més important en el nostre territori per la gran quantitat de persones que procedeixen d’àrees endèmiques. En la nostra zona roman infradiagnosticada ja que s’han detectat molts menys casos dels esperats. La sèrie però té un elevat número de malalts amb afectació visceral. Donat el risc de transmissió no vectorial en un país no endèmic i les complicacions cròniques de la malaltia, s’hauria de fomentar la informació i el cribatge en la població de risc. Així doncs, amb l’ increment dels viatges internacionals i la immigració, a Catalunya, ha augmentat el número de pacients amb malalties infeccioses emergents, moltes d’elles importades des de zones tropicals i subtropicals. El risc que representen per a la salut pública sembla ser baix, encara que els canvis que s’estan produint en relació a la crisi econòmica mundial, a la introducció biogeogràfica de vectors, al canvi climàtic i sobretot a l’aparició de reservoris naturals d’aquestes infeccions, ens situen en un context imprevisible. Un accés universal a l’assistència sanitària, que aquesta sigui d’expertesa i qualitat per garantir un diagnòstic i tractament immediat, junt a una vigilància epidemiològica estreta i les intervencions en Salut Pública corresponents, són peces clau per a preservar la Salut de la nostra població.
Nowadays, the health care of infectious diseases urgently demands a change of scenario due to socioeconomic and climatic changes as a consequence of the globalized world, and requires a specialization and particular expertises from the health community. This issue is dealt in this study. The present doctoral thesis focuses on the analyses of health data of international travellers and immigrants in the area of Nothern Metropolitan Barcelona residing in Badalona and Santa Coloma de Gramanet from 2007 to 2013. Data was collected in primary care (International Nothern Metropolitan Health Unit) and in a tertiary level hospital (Hospital Germans Trias i Pujol), which shapes the territorial unit of International Health Northern Metropolitan Health Program of the International Catalan Institute of Helath (PROSICS) approved in 2012. The doctoral thesis is divided into four projects which are based on four premises: 1. After 5-years of economic crisis, it has been a change in the risk profile of the international traveller who travels for work. The number of travellers as well as the risk factors to which they are exposed to acquire infectious diseases have increased. 2. The incidence of dengue and chikungunya is increasing in the Metropolitan area north of Barcelona at the expense of imported cases from international travellers. So far, have not appeared cases of dengue and chikungunya in the local area, although it is densely populated by the vector Ae.albopictus. 3. 90% of cases of infections Strongyloides stercolaris diagnosed in our area are imported by immigrants. Partly, it is an asymptomatic infectious and diagnosis is based on clinical suspicion and / or analysis, and the active search for parasites. We will have to implement screening protocols in immunocompromised immigrants for the high mortality that can lead to reactivation of the infection. 4. Chagas’ disease is the most important emerging disease in our country due to people who come from endemic areas. In our area, this infectious disease remains underdiagnosed, because of fewer cases detected than expected. However, Chagas’ patients have a remarkable incidence of visceral involvement. Given the risk of non-vector transmission in a country which is not endemic as well as for the chronic complications of the disease, it should be promoted the information and screening in the population at risk. So, the number of patients with emerging infectious diseases, of which many of them are imported from tropical and subtropical areas, has grown in Catalonia with the increase in international travels and immigration. The risk that they represent to public health appears to be low, although the changes taking place in relation to the global economic crisis, with the introduction of biogeographic vectors, particularly climate change, and the occurrence of natural reservoirs of these infections, lead us to an unexpected context. Finally, the key for preserving the health of our population is the universal access to health care, being of expertise and quality to ensure immediate diagnosis and a precise treatment, along with a narrow epidemiological surveillance and the public health interventions related.

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Sivell, Michael. "Cryptococcosis: a proteomic investigation of an emerging fungal disease." Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/10185.

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Fungal infections are increasing in frequency throughout the world. The development of new diagnostic and treatment strategies has not kept pace with this increase. The result is a high incidence of infection recurrence and high mortality rates. The pathogenic yeasts Cryptococcus neoformans and Cryptococcus gattii provide an excellent system for determining the spectrum of fungal growth and infection, from environmental saprotrophic growth, to self-limiting infection and through to severe primary infection. Cryptococcus cells obtained from pulmonary infection, and infected rat lung tissue, represented technically challenging sample types that required significant protocol development prior to comparative analysis. This subjected the obtained data to a number of experimental caveats. Despite the significant impediments to experimentation, the advances made in protocol development by this study allowed for the first in vivo analysis of intracellular Cryptococcus protein expression. This result provided proof of concept for global "–omics" analysis of Cryptococcus from an in vivo sample. In addition, qualitative data were obtained that offered insights into fungal pathogenesis at the protein level and highlighted a number of Cryptococcus proteins that could be exploited as drug targets. Furthermore, the identification of host lung proteins and systemic cytokines of biological relevance to pulmonary cryptococcosis provides proof of the ability of comparative proteomics to elucidate future drug targets, biomarkers and diagnostic markers from in vivo mammalian infection models. The studies’ most significant achievement has been the advances made in protocol development. It is hoped that these advances will lead to further, potentially quantitative, analysis of fungal pathogens under in vivo conditions, along with continued development of novel therapeutic and diagnostic options for pathogenic fungi.

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Weldon, Ché. "Chytridiomycosis, an emerging infectious disease of amphibians in South Africa / C. Weldon." Thesis, North-West University, 2005. http://hdl.handle.net/10394/860.

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The sudden appearance of chytridiomycosis, as the cause of amphibian deaths and population declines in several continents suggests that its etiological agent, the amphibian chytrid fungus Batrachochytrium dendrobatidis, was introduced into the affected regions. However, the origin of this virulent pathogen is unknown. Efforts were directed to determine the occurrence of chytridiomycosis in Africa, whether the disease had been introduced into South Africa in recent years and how wild frog populations were affected by infection. A chytridiomycosis survey of 2,300 archived and live specimens involving members of the Pipidae family in sub-Saharan Africa, as well as a number of unrelated frog species in South Africa was conducted by histological diagnosis of skin samples. The epidemiological evidence indicated that chytridiomycosis has been a stable endemic infection in southern Africa for 23 years before any positive specimens were found outside Africa. The occurrence of chytridiomycosis in South Africa can be described as widespread both in terms of geographical distribution and host species and generally infection is not associated with adverse effects at the individual or population level. It was proposed that the amphibian chytrid originated in Africa and that the international trade in the African clawed toad Xenopus laevis that commenced in the mid 1930s was the means of dissemination. A risk assessment of the X. laevis trade demonstrated that chytridiomycosis could spread through this pathway and culminated in the development of a management protocol to reduce the risks of spreading disease through this animate commodity. Initial comparative genetic analysis of B. dendrobatidis strains isolated from South African frogs with a global set of 35 strains, suggests that analysis of a more geographically diverse set of southern African strains is needed before this line of argument can support or reject the "out of Africa" hypothesis.
Thesis (Ph.D. (Zoology))--North-West University, Potchefstroom Campus, 2005.

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Carr, Rachel Genevieve. "Species Body: Xenotransplantation, Emerging Infectious Disease, and Imaginaries of the (Non-)Human." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/18405.

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Animal-to-human transplantation (xenotransplantation) opens up biological circulation across what are often understood as species barriers, mobilising non-human animal tissues, and, potentially, microbes. Xenotransplantation practices further trouble the alleged barriers between humans and other animals as some researchers augment pigs with human genes to make their tissues more immunologically acceptable. From a regulatory point of view, the possibility that infectious disease might be spread by the practice of xenotransplantation poses significant problems. Yet, in the field of xenotransplantation, contagion and cross-species exchanges have been dealt with in surprisingly different ways in various contexts. As I demonstrate, in four case studies, great apes have been treated very differently from pigs, and there are striking divergences between the forms of regulation and practice adopted in New Zealand, the United States, and Australia. Particular imaginaries inform each context of xenotransplantation practice and regulation, and are structured in terms of a certain regime of power. In this thesis, I contend that the field of xenotransplantation is shaped by the interplay of sovereign and security forms of power and that this interplay explains in part the different regulatory responses to xenotransplantation internationally. In each chapter, I analyse a different set of knowledges, imaginaries and narratives that cut across philosophy, epidemiology, tourism, conservation, and primatology, to illustrate how interconnections, borders or boundaries are treated in the xenotransplantation field. Drawing on interviews with experts in the field, and Foucault’s typology of power, I demonstrate that the apparatuses of sovereignty and security dynamically govern the exploitation of animal tissues for humans.

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McFarlane, Rosemary Anne. "Linking patterns of ecological change and emerging infectious disease in the Australasian region." Phd thesis, Canberra, ACT : The Australian National University, 2014. http://hdl.handle.net/1885/14475.

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The rise in emerging infectious diseases (EIDs) over the last 4 decades is concurrent with dramatic changes in global ecology. The two are likely to be associated, given that zoonoses, particularly those of wildlife origin, make up the majority of these disease. EIDs of animals (and invertebrates and plants) are also reported. The objective of my research is to understand how human and animal EIDs in the Australasian and neighbouring South East Asian and East Asian regions are influenced by ecological change. To achieve these objectives the total reported human and animal EIDs, the diversity and characteristics of hosts of zoonotic EIDs and the relationship between major periods of land-use change and infectious disease emergence have been examined. A case study on Hendra virus emergence in eastern Australia has enabled consideration of these and additional interacting variables, including that of virus, host and climatic factors. Source data regarding EIDs were obtained by systematic review of data bases SCOPUS, CABI and Web of Knowledge. Ancillary data were obtained from the IUCN Red List, vegetation, primary production, land-use, rainfall and temperature, Hendra disease outbreak sites, flying fox camp locations and horse distribution. Historical data on disease, development and environmental change in Australia were also sourced from literature. 104 human, 53 livestock and 23 wildlife EIDs are reported for the Australasian-Asian region,1973-2010. Of the human EIDs, 67% are zoonoses, 63% of these are from wildlife, almost exclusively from wild mammals. Novel zoonoses are reported exclusively from bats. Wild mammal hosts of EIDs are more likely to be associated with human-modified land-uses (OR = 15.02; 95 % CI 5.87 - 38.41), here described as synanthropic. Hosts are also likely to be of low conservation risk (OR = 8.56; 95 % CI 3.04 - 24.08). In a continent-wide study of human and animal EIDs in Australia, the country with the greatest EID literature in the region, land-use change is temporarily and biologically plausibly associated with 22% of the total 90 EIDs reported. Queensland is the most frequent location for these. The current decades of accelerated infectious disease emergence are also examined in an historical context. For Hendra virus, the natural hosts are 4 species of increasingly synanthropic fruit bats for which natural habitat loss has been dramatic, and recent, particularly in the state of Queensland. For the 1994-2010 outbreaks, proximity to roost camps of flying foxes in urban and rural residential areas is an important risk factor, here calculated as the odds of outbreaks in postal areas containing fruit bat camps (OR = 40.5, 95% CI (5.16 - 317.52). All outbreaks have occurred within the nightly feeding range of flying fox camps. Despite the strong seasonality of outbreaks (p = 0.013, 95% CI 0.57-0.98), no climatic or vegetation signatures are evident. Recent, dramatic, anthropogenic ecological change, particularly land-use change, puts pressure on wild species to adapt or perish. It is hypothesised that synanthropic species have become an important new source of pathogens for humans through this process.

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Burgan, Sarah Catherine. "From Tolerance to Transmission: Linking Within-Individual to Community-Level Disease Processes." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6193.

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Hosts have two main strategies for coping with infections: resistance and tolerance. Resistance is aimed at preventing or eliminating parasites, whereas the goal of tolerance is to maintain performance regardless of parasite burden. The balance between resistance and tolerance within a host may mediate host competence, or the propensity of a host to infect other hosts or vectors. Hosts with high tolerance and low resistance to an infection, for instance, may be highly competent and possess the greatest potential to act as superspreaders. These superspreading hosts will contribute disproportionately to transmission, thus posing the greatest risk to other hosts within a population or community. Understanding the drivers of heterogeneity in host competence therefore has broad implications for the management of infectious diseases in nature. Host tolerance is typically quantified as the slope of the relationship between host performance and parasite burden. The majority of host tolerance studies have been conducted at the level of genotypes, populations and species. Individual hosts often exhibit variation in competence, with some individuals contributing more or less to transmission than the population/species average. Despite the clear importance of understanding tolerance at the individual-level, such studies are rare and may be particularly challenging in field contexts due to the need for repeated performance-burden measurements. I used the house sparrow (HOSP) – West Nile virus (WNV) system to investigate differences among two alternative approaches to estimating individual tolerance: the scope and position methods. The scope method estimates tolerance traditionally as the slope of multiple performance-burden measurements over time within an individual; alternatively, the position method required only one measurement for each individual, thus characterizing tolerance via among-individual variation in host defense. We found strong relationships between scope and position estimates of individual tolerance, suggesting that the position method may be an appropriate proxy to use in field studies. I also compared tolerance estimates derived from different metrics of performance. There were weak correlations among these estimates of tolerance, implying that tolerance estimated by measuring a single trait may not be indicative of tolerance at the level of the whole individual or their contribution to disease processes. Understanding the physiological mediators of host competence may help to pinpoint at-risk and risky individuals (or genotypes, populations and species) within natural communities, thus facilitating the development of more targeted disease management strategies. Cytokines and glucocorticoids have been identified as potent mediators of host defense. Pro-inflammatory cytokines may act to promote resistance, whereas anti-inflammatory cytokines and glucocorticoids tend to mediate host tolerance. I investigated the dynamics of pro-inflammatory cytokine IFN-γ, anti-inflammatory cytokine IL-10, and the major avian glucocorticoid, corticosterone (CORT), following WNV exposure in HOSP. I then assessed the influence of these three mediators on resistance and tolerance to WNV infection. I found unusual dynamics for the three mediators across the infection period: IFN-γ expression was not induced by WNV exposure, IL-10 expression was dampened by WNV exposure, and CORT levels were higher in unexposed individuals. Despite the unique response of HOSP to WNV exposure seen here, we did find that constitutive expression of IFN-γ and IL-10 mediate resistance and tolerance to WNV, respectively. Unexpectedly, we also found evidence for protective (pro-resistance) effects of CORT, which contrasts with previous evidence for the role of CORT in mediating WNV infections. Combined, the results of this study suggest that hosts with constitutively high IL-10 and low IFN-γ expression may have high potential to act as superspreaders of disease, thus becoming critical targets in designing WNV-control strategies in passerines. The methods by which we quantify host tolerance may greatly affect the conclusions we are able to draw from such studies. To date, a variety of definitions and techniques have been used to study tolerance in animals. In chapter three, I briefly summarize past plant and animal tolerance research, highlighting discrepancies among researchers in their motivations, definitions and techniques for studying tolerance. For instance, I discuss biases in the literature regarding the use of range versus point tolerance, vigor, and laboratory versus field studies. In particular, I expound upon the nature of the performance metrics used in the majority of tolerance estimations in the literature, and discuss the ecological implications of these metrics. To conclude, I offer suggestions for overcoming the challenges associated with studying tolerance and encourage a unified way forward in the field, emphasizing the selection of system-specific and ecologically relevant tolerance metrics. My thesis research has employed physiological and behavioral methods in an ecological context to better understand the heterogeneities that exist in host competence. By combining empirical data in the HOSP-WNV system with conceptual and methodological strategies for assessing host defenses, this research has broadened our knowledge of host responses in the WNV system in a manner that may be applicable to understanding and managing disease dynamics in diverse natural communities.

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40

Rigot, Thibaud. "The space-time distribution of Palearctic Culicoides spp. vectors of Bluetongue disease in Europe." Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209835.

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Abstract :Bluetongue (BT) is a vector-borne infectious disease primarily transmitted to even- toed ungulates by the bite of several Culicoides species. The global distribution of BT can be attributed to the ubiquity of its vectors and its rapid spread, likely to the enhancement of human activities (intensification of animal production, trans- port, changing habitat). During the last decades, BT established in Southern Europe and more recently emerged in Northern Europe, causing the death of millions of domestic ruminants. On the same time, a Belgian research project has been set up to develop remote-sensing tools to study the EPidemiology and Space-TIme dynamicS of infectious diseases (EPISTIS). In that general framework, this thesis aimed to study the space-time distribution of the main Culicoides vectors occurring in Italy and Belgium, at two different scales. Firstly, we aimed to clarify the role of several eco-climatic factors on the regional-scale distribution of C. imicola in time, based on weekly samplings achieved throughout Italy from 2001 to 2006 and to develop an easy-to-use and reproducible tool, which could be widely validated on the basis of former vector sampling and freely accessible remote-sensing data. Secondly, we aimed to investigate how Culicoides species were distributed in the fine-scale habitat encountered throughout the agro-ecological landscapes of Belgium, while recent studies have suggested that the landscapes configuration could explain the spatial distribution of BT. In the first part, we showed that an autoregressive model where the observed monthly growth rate is predicted by monthly temperature, allowed predicting >70% of the seasonal variability in C. imicola trap catches. The model predicted the seasonality, the altitudinal gradient, and the low populations’ activity taking place during the winter. Incorporating eco-climatic indices such as the Normalized Difference Vegetation Index into the model did not enhance its predictive power. In the second part, we quantified how Culicoides populations are spatially structured in the neighbourhood of farms, and demonstrated the unexpectedly high level of population found in forest. We also showed how four classes of land use could influence the relative abundances of Culicoides species in the agro-ecological landscapes of Belgium. Although in summer, BT vectors were abundant in each of the four classes investigated, their relative abundances varied strongly as a function of sex, species and environmental conditions, and we quantified these variations. Finally, we also presented a new method to quantify the interference between Onderstepoort light traps, and used it to measure their range of attraction for several of the most common BT vectors species in Northern Europe. The model developed on C. imicola in Italy provided enthusiastic perspectives regarding the regional-scale analyses of its distribution in time, although further improvements are nevertheless required in order to assess the broad scale ecology of BT vectors throughout Europe. Mapping the abundances of C. imicola in Sardinia high- lighted an important lack of reliability attributable to the many land use classes that are currently not sampled in the vector surveillance achieved across Europe. Together with the novelties presented in the second part and the recent findings establishing that BT could circulate among wild hosts in both epidemiological systems (i.e. in Southern and Northern Europe), we call for increasing epidemiological and entomo- logical studies at the interface between farms and the surrounding natural habitats. Last, depicting in time the landscape-scale findings for Northern Europe highlighted how dramatic could be the role played by intensive farming practices to maintain BT within the agro-ecological landscapes studied and to facilitate its circulation between them. Quantifying the amplitude of the risk of disease transmission linked to these practices would require a further complex modeling approach accounting simultaneously for the diel activity of hosts, mainly resulting from the farming activities, the diel activities of different vector species and the landscapes configuration found in contrasted agro-ecological systems.

Résumé :La fièvre catarrhale ovine (FCO), encore appelée maladie de la langue bleue, est une maladie infectieuse des ruminants transmise par la piqûre d’un vecteur de type moucheron appartenant au genre Culicoides (Diptera :Ceratopogonidae). L’ubiquité de ses vecteurs peut expliquer son succès d’installation à l’échelle globale. Par ailleurs, sa rapide expansion a été grandement facilitée par l’importante activité anthropique (élevage, transport, modification de l’habitat) et peut-être même par les changements climatiques globaux. La FCO a été récemment qualifiée de maladie infectieuse émergente en Europe du fait de (i) son récent établissement dans la région, bien au delà de son aire de répartition traditionnelle, (ii) de sa forte capacité de dispersion affectant chaque jour un nombre plus important d’hôtes et enfin (iii) de sa forte virulence. Après avoir détaillé les caractéristiques majeures des deux principaux foyers de FCO rencontrés en Europe depuis 1998, la présente thèse s’est plus particulièrement intéressée à l’étude de la distribution spatio-temporelle de ses principaux vecteurs dans le sud (partie 1) puis dans le nord (partie 2) de l’Europe, à différentes échelles. Dans la première partie, un modèle discret, spatialement et temporellement explicite, a été développé afin de mesurer l’influence de différents facteurs éco-climatiques sur la distribution de Culicoides imicola, principal vecteur de la FCO dans le Bassin Méditerranéen. Les profils mensuels de distribution rencontrés en Sardaigne durant 6 années consécutives ont ainsi pu être reconstitués, principalement sur base de la température. Une cartographie de l’abondance de C. imicola sur le territoire a permis de mettre à jour le manque d’information sur sa distribution en dehors des exploitations agricoles. Dans la deuxième partie du travail, nous nous sommes penchés sur la distribution spatiale des Culicoides tels qu’on peut les rencontrer au sein de différents paysages agro-écologiques de Belgique. Nous avons ainsi pu décrire la structure adoptée par les populations de Culicoides au voisinage des fermes ainsi que quantifier l’importante population présente dans les forêts avoisinantes. Nous avons par ailleurs montré l’influence de différentes catégories d’utilisation du sol sur l’abondance et la composition en espèces. Enfin, nous avons présenté une méthode permettant de quantifier l’interférence entre des pièges lumineux utilisés dans un même paysage pour échantillonner les populations, et l’avons utilisé afin de mesurer leur rayon d’attractivité sur les espèces vectrices les plus communément rencontrées dans le nord de l’Europe. En guise de conclusion générale et conjointement aux récentes découvertes de cas de FCO au sein de la faune sauvage européenne, nous appelons à réaliser un plus grand nombre d’études éco-épidémiologiques à l’interface entre exploitations agricoles et zones (semi-) naturelles avoisinantes. En outres, les résultats présentés dans la seconde partie ont été mis en relation avec le mode de fonctionnement journalier de nos exploitations agricoles. Nous avons ainsi pu déduire le rôle dramatique joué par les pratiques agricoles intensives dans le maintien du virus de la FCO au sein de nos paysages agro-écologiques, ainsi que dans sa circulation d’un paysage à l’autre. Un cadre de modélisation complexe permettant une analyse simultanée de l’activité nycthémérale des hôtes de la FCO et de ses vecteurs Culicoides en fonction de la configuration des paysages agro-écologiques est néanmoins requis afin de quantifier l’amplitude du risque de transmission de la FCO lié aux pratiques agricoles intensives.
Doctorat en Sciences agronomiques et ingénierie biologique
info:eu-repo/semantics/nonPublished

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Lambert, Rebecca Click. "Chagas Disease in the United States: the Emerging Threat and the Role Climate and Awareness Play in Its Spread." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/42377.

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This study evaluates the roles of temperature variability and disease awareness in the emergence of Chagas disease (American trypanosomiasis). Chagas disease is endemic in Latin America and primarily spreads to humans directly via the triatomine vector. Hosts for most triatomine species are mainly rodents and occasionally dogs. The disease itself is caused by a parasitic protozoan, Trypanosoma cruzi (T. cruzi) which is found in the triatomineâ s feces and is often spread while the triatomine is consuming a blood meal. T. cruzi from feces enters the body via an abrasion on the skin, the mucous membranes, conjunctivae, or through consumption. To determine the risk of Chagas disease transmission one must define qualities that make the triatomine an effective disease vector as well as investigate the level of disease awareness among physicians and the population within the vectorâ s range. This thesis maps triatomine species within the U.S. that harbor T. cruzi naturally and that exhibit qualities of domesticity. These qualities are defined by whether the species bites humans and dogs as well as reports that the species has been found in the domestic setting. Ranges illustrating temperature thresholds for increased triatomine activity for 2000 and 2030 are also depicted. Additionally, outcomes of a physician survey are presented to gauge the status of Chagas disease awareness in areas at higher risk for disease transmission. Results reveal limited consideration of Chagas disease in physician diagnosis despite the higher risk range which extends through the southern U.S. and is predicted to expand significantly by 2030.
Master of Science

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42

Wong, Yu Hin. "Highly pathogenic avian influenza (H5N1) in Hong Kong, 1997-2014 : towards an urban biopolitical immunology." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/highly-pathogenic-avian-influenza-h5n1-in-hong-kong-1997--2014-towards-an-urban-biopolitical-immunology(dde69f59-8dd0-48ee-819f-c5ef98d3b0b1).html.

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The thesis traces the successive urban responses made by the Hong Kong government from 1997 to 2014, in an attempt to achieve “imagined immunity” for the city. The urban responses being analysed are efforts to regulate the ways in which “live poultry” (especially live chickens) is metabolized and circulating in the city. The efforts are made to re-order the human-birds-microbes relationships in Hong Kong - a process conceptualized as “re-urbanization of nature.” The consequence of these re-urbanization of nature processes, led to changes in the specific practice of consuming “live poultry” in the city. Four periods of re-urbanization of nature are identified in the analysis, and it is argued that in each wave of restructuring there were markedly different frames constructed to generate distinctive meanings of the “contagion condition,” imagined urban immunity, and practices of re-urbanization of nature. Their meanings and resultant practices were products of negotiations, within an entangled web of human and nonhuman features in particular periods. The context of these interventions and the biopolitical contestations are analyzed in the thesis. It is then argued that such contingencies and context-sensitive processes, call for further studies of post-epidemic urban changes. The thesis also explores the possibility of developing a theoretical framework of “urban biopolitical immunology” to accomplish the inquiry. By so doing, it seeks to contribute to studies of the politics of contemporary epidemics, and to research on the production of urban nature.

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Monagin, Corina Grigorescu. "Case study : how are perceptions of risk in wet markets informing policy implementation of emerging infectious disease control in Guangdong, China." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.590510.

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Dhondt, Kévin. "Etude des mécanismes de haute pathogénicité des Henipavirus." Thesis, Lyon, École normale supérieure, 2014. http://www.theses.fr/2014ENSL0954/document.

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Les Henipavirus sont des paramyxovirus zoonotiques émergents hautement pathogènes. Ils sont capables d’infecter un large spectre d’hôtes incluant notamment la chauve-souris frugivore (réservoir naturel), le porc et l’homme. Etant donné leur très grande dangerosité et en l’absence de traitements curatifs ou prophylactiques efficaces, ces virus doivent être manipulés dans un laboratoire de classe P4. Dans une première partie, nous étudions l’effet de composés glyco-amino-glycanes sur l’infection par les Henipavirus ainsi que leur potentielle application en tant que traitement. Dans une seconde partie, nous nous attachons à comprendre les interactions entre le système immunitaire de l’hôte et le virus. Afin de mieux comprendre ces interactions, nous avons utilisé une approche basée sur l’utilisation de souris déficientes pour certaines voies de l’immunité. En effet, bien que les récepteurs cellulaires au virus (EFN B2 et B3) soient fonctionnels chez la souris, celle-ci est résistante à l’infection par voie intrapéritonéale. Nous avons analysé la susceptibilité au virus Nipah (NiV) de souris privées de différentes voies du système immunitaire inné et adaptatif. Les résultats obtenus permettent d’envisager certaines lignées de ces souris comme nouveaux modèles animaux pour l’étude de l’immunopathogénèse du NiV. Cette étude suggère aussi que le système interféron de type I joue un rôle crucial dans la limitation de la propagation virale vers le cerveau et que les lymphocytes T sont nécessaires à la complète élimination du virus. Les macrophages jouent, quant à eux, un rôle central et indispensable, à l’interface entre système inné et adaptatif. Enfin, nous abordons les prémices d’un projet visant à identifier les différences d’interactions au niveau moléculaire entre les protéines non-structurales du virus et les protéines du système immunitaire inné chez l’Homme et la souris afin de voir s’il se dégage des différences d’interactions pouvant expliquer les différences de pathogénie. Ces travaux ont donc permis d’identifier de nouveaux modèles animaux et de mieux caractériser les interactions entre le pathogène et le système immunitaire de l’hôte, de l’échelle moléculaire à l’échelle de l’organisme entier. Néanmoins, les mécanismes précis de ces interactions restent à élucider et permettront certainement de mieux comprendre la grande diversité de pathogénie des Henipavirus
Henipaviruses are highly pathogenic emerging zoonotic paramyxoviruses. They can infect a broad spectrum of mammals including flying foxes (Pteropus fruit bats), its reservoir, pigs and humans. As there are neither therapeutic drugs nor efficient prophylactic treatment towards these highly lethal viruses, they have to be manipulated in biosafety level-4 laboratories. In the first part of this thesis, we study the role of glyco-amino-glycans on Henipavirus infection and their potential use as treatment. In the second part, we describe the interaction between the host immune system and the pathogen. To investigate these interactions, we took advantage of different transgenic mouse models deficient for some immune pathways. Indeed, although mice possess the viral entry receptor for Henipaviruses, they do not succumbed to intraperitoneal infection. We analyzed the susceptibility to Nipah virus (NiV) infection of mice deleted for different components of innate and adaptive immune systems. Obtained results showed that some of these mice can be used as new models for NiV immunopathogenesis study. This study also suggests that type I interferon system plays a major role in limitation of viral spreading to the brain and that T cells are necessary for full viral clearance. Macrophages act at the crossroad of immunity, between innate and adaptive system. Finally, we deal with the preliminary phases of a project which aims to identify the differences, at a molecular level, of interaction between non-structural viral proteins and innate immunity proteins in mice and human. Such differences could explain the different clinical patterns that are observed in these species. In conclusion, this thesis allowed to identify new animal models and to better characterize host-pathogen interactions, from molecular to whole organism level. However, the precise mecanisms of these interactions remain to be elucidated and would probably help to understand the great diversity of pathogeny of Henipaviruses

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Black, Michael David. "Central city youth and HIV/AIDS an emerging community construct: Finding the best fit ofprovention and intervention service." CSUSB ScholarWorks, 1998. https://scholarworks.lib.csusb.edu/etd-project/1814.

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46

Dragoni, Filippo. "Antiviral drug development for treatment of acute and chronic viral infections." Doctoral thesis, Università di Siena, 2021. http://hdl.handle.net/11365/1127988.

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Background Viruses are aetiologic agents of several human infectious diseases, which can be distinguished into acute and chronic. Among the agents causing acute infections, arboviruses, such as Dengue (DENV), West Nile (WNV) and Zika (ZIKV) Viruses, have increasingly spread worldwide. Moreover, the newly discovered Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), causing the COVID-19 disease, is responsible for an incredibly quantity of infections and deaths. Conversely, the Human Immunodeficiency Virus (HIV-1) is a well-known pathogen able to cause chronic latent infection, but it still represents a global public health concern. The main strategy for combating viral infections is a combination of vaccination and antiviral drugs. However, vaccines are available only for a minority of viral pathogens, thus the demand for new antiviral strategies has significantly increased. Anyway, the screening of candidate compounds requires the assessment of their antiviral effects in vitro. Results and discussion An easy-to-perform and fast flavivirus immunodetection assay (IA) was developed to determine antiviral activity of promising compounds against ZIKV and DENV, able to distinguish between the inhibitory effect of molecules targeting the early and post-budding phases of viral replication cycle. Considering that the activity of sofosbuvir, a nucleotide analog licensed for HCV infection, has been documented against different flaviviruses, we investigated whether it may exert an activity also against WNV. We determined for the first time the antiviral activity of sofosbuvir against WNV in both cell-based and enzymatic assays. Moreover, in vitro selection and molecular docking experiments indicated that HCV and WNV share a similar sofosbuvir resistance pattern. The “ORIGINALE CHEMIAE in Antiviral Strategy” project aims to identify promising broad-spectrum antivirals by taking advantage of the Multi-Component Chemistry strategy. Antiviral activity of molecules was determined in vitro against DENV, WNV, HIV-1 and SARS-CoV-2. Two compounds were able to inhibit viral replication against two different families of viruses (DENV/WNV and SARS-CoV-2), and two compounds were able to inhibit viral replication against viruses with remarkable differences in their replication cycle (DENV/WNV and HIV-1). At the beginning of the pandemic, an Italian network named SCIRE (SARS-CoV-2 Italian Research Enterprise) was created in order to trace SARS-COV-2 evolution. By NGS whole genome sequencing, it was defined that the initial outbreak in Italy was mainly attributable to the SARS-CoV-2 lineage B.1 and to its uncontrolled circulation for an estimated period of 4 weeks. Developing strategies to eradicate chronic HIV-1 infection are a high priority. Recently, it was hypothesized that maraviroc (MVC), may exert a latency reversing effect in addition to its antiviral activity. Thus, the MVC-mediated HIV-1 induction was explored. An increased HIV-1 expression was detected at the highest MVC concentration in two of the three cell line models tested. In ex vivo CD4 T cells, MVC-mediated induction was detected sparsely on individual samples. Such evidences suggest the role of MVC as a weak latency reversing agent of the HIV-1 provirus induction. Conclusions Control of viral infections is a continuous challenge for public health. The development of effective antiviral compounds could be reasonably the key to halt the spread or to mitigate severe clinical manifestations of acute viral diseases. Moreover, antiviral therapy is essential to the maintenance of undetectable viral loads in chronic infection. Furthermore, developing of compounds able to exert a reversal latency effect may be a remarkable benefit in exacerbate chronic viral infections. In conclusion, the key concept of this thesis is to underline the strong need, and partially participate, in enhancing antiviral therapies strategies to counteract the burden of both acute and chronic viral diseases.

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Steuber, Jarod Gregory. "THE COST OF AN EMERGING DISEASE: MYCOBACTERIUM LEPRAEINFECTION ALTERS METABOLIC RATE OF THE NINE-BANDED ARMADILLO ( DASYPUS NOVEMCINCTUS)." Akron, OH : University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1195236347.

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Thesis (M.S.)--University of Akron, Dept. of Biology, 2007.
"December, 2007." Title from electronic thesis title page (viewed 02/23/2008) Advisor, Francisco Moore; Co-Advisor, Brian Bagatto; Committee members, Peter Niewiarowski, Joel Duff; Department Chair, Bruce Cushing; Dean of the College, Ronald Levant; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

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Oliver, Jennifer Betts. "The Prevalence of Nelson Bay Virus in Humans and Bats and its Significance within the Framework of Conservation Medicine." Digital Archive @ GSU, 2007. http://digitalarchive.gsu.edu/iph_theses/7.

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Public health professionals strive to understand how viruses are distributed in the environment, the factors that facilitate viral transmission, and the diversity of viral agents capable of infecting humans to characterize disease burdens and design effective disease intervention strategies. The public health discipline of conservation medicine supports this endeavor by encouraging researchers to identify previously unknown etiologic agents in wildlife and analyze the ecologic of basis of disease. Within this framework, this research reports the first examination of the prevalence in Southeast Asia of the orthoreovirus Nelson Bay virus in humans and in the Pteropus bat reservoir of the virus. Contact with Pteropus species bats places humans at risk for Nipah virus transmission, an important emerging infectious disease. This research furthermore explores the environmental determinants of Nelson Bay and Nipah viral prevalence in Pteropus bats and reports the characterization of two novel orthoreoviruses isolated from bat tissues collected in Bangladesh.

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Clostio, Rachel Wallace. "Use of environmental variables to infer gene flow and population structure in the gopher tortoise (Gopherus polyphemus) and predict the seroprevalence of an emerging infectious disease." ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1230.

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Understanding worldwide declines in reptiles due to factors such as habitat loss and emerging infectious disease has become an increasingly important focus in conservation biology. Here, I use novel approaches from the field of landscape genetics to combine spatial genetic data with landscape data at both regional and local spatial scales to explore natural and anthropogenic landscape features that shape population structure and gene flow in a federally threatened reptile, Gopherus polyphemus. I also utilize approaches from the field of spatial epidemiology to examine the extent to which environmental variables can be used to predict the seroprevalence of an associated pathogen Mycoplasma agassizzi in gopher tortoise populations. Using mitochondrial data, I find evidence of a historical barrier to gene flow that appears to coincide with the Apalachicola River. I also discover low genetic diversity and evidence of population bottlenecks in the western portion of the range. My evaluation at the regional scale shows that dispersal is limited by geographic distance, areas of low elevation and major roads ways. A finescale study reveals no evidence of spatial genetic structure within a 14 x 35 km area. However, soil type is significantly correlated with pairwise genetic distances between individuals, suggesting that this variable influences fine-scale population structure in the gopher tortoise. In addition to soil, high density canopy cover is an important factor impeding gene flow at the local level for females, while land cover type explains some of the genetic variance between males. Finally, temperature and precipitation appear to be important predictors of the seroprevalence of the pathogen Mycoplasma agassizii in gopher tortoises. The probability of an individual testing seropositive for exposure to this disease increased with high temperature and low precipitation values. The methods presented in this dissertation evaluate novel approaches for assessing the influence of environmental variables on population structure, dispersal and disease occurrence and could be applied in future studies of other threatened and endangered taxa.

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Alves, Davi Mello Cunha Crescente. "O impacto da síndrome do nariz-branco no estado de conservação dos morcegos norte-americanos." Universidade Federal de Goiás, 2013. http://repositorio.bc.ufg.br/tede/handle/tede/3807.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The White-Nose syndrome is an emergent infectious disease that had already killed almost six millions North American bats and spread more than two thousand kilometers. Even so, studies about their possible impacts upon hosts are still lacking, principally upon all the susceptible North American bats. We predicted the consequences of the WNS spread in the North American hosts by generating an environmental suitability map for the disease, and then, we overlaid with the extension of occurrence of all hibernating bats in North America. We assumed that all intersection localities will somehow negatively affect bat’s local populations, and we reassessed their conservation status based on their potential population reduction. 16% of the North American hibernating bat fauna were considered threatened under this WNS potential spread. We believe our results could contribute with governments conservation actions.
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