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Spenillo, Jocelyn K. "Nurse’s Perceptions of Visitor’s Adherence to Transmission-Based Precautions." Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/honors/316.
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Transmissions based precautions are measures implemented in various clinical health care settings as a means to prevent the transmission of infectious diseases and decrease instances of healthcare acquired infections (HAI). HAI’s result in increased cost to hospitals, longer hospitalization for patients, increased patient suffering, and fatal patient outcomes. While staff member adherence to transmissions based precautions are mandated through various organizations and hospital policies, a review of literature indicates little research has been conducted regarding visitor compliance with transmission-based precautions. The potential implications in healthcare from visitor non-adherence acquired infections are unknown; revealing a gap in literature and supporting the need for further research to describe the phenomenon. Through utilization of a descriptive online survey instrument, the purpose of this descriptive study is to gain insight into why nurses believe visitors may or may not be compliant with transmission-based precautions. To collect the data, an online descriptive survey instrument was developed and distributed via email to all graduate students’ enrolled East Tennessee State University’s College of Nursing. Only ten participants met the eligibility requirements to participate in this study. Data was analyzed though a predictive analytics software and grouping responses into themes. Responses suggest that nurses feel visitors are not complying with transmission-based precautions because of a lack in education, not perceiving the infection as a threat, prior exposure to loved one at home, and inconvenience.
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CHOUQUET, CECILE. "Transmission du vih-1 de la mere a l'enfant : modelisation bayesienne du moment de la transmission." Paris 11, 1998. http://www.theses.fr/1998PA11T013.
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Tscherning, Charlotte. "Déterminants biologiques et génétiques du VIH-1 et rôle du placenta dans la transmission materno-foetale." Lyon 1, 1998. http://www.theses.fr/1998LYO1T187.
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Thompson, J. M. "Phytophthora Infestans in Potato Tubers : Infection and Transmission." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501594.
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Voirin, Nicolas. "Analyse et modélisation de la transmission de la grippe nosocomiale." Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10151.
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Les conséquences des épidémies de grippe nosocomiale (GN) pour les patients en termes de morbidité et mortalité sont importantes. Cependant, la présentation clinique des cas, la fréquence de l’infection, le risque d’infection parmi les patients, la transmission et les mesures de contrôle les plus adaptées restent mal connues. Une analyse originale de la littérature nous a permis de synthétiser les connaissances sur la GN. Puis sur la base d’une étude prospective menée pendant 3 saisons de grippe de 2004 à 2007, nous avons présenté une description clinique des cas de grippe observés à l’hôpital Edouard Herriot de Lyon. Nous avons ensuite développé un modèle statistique d’analyse du risque de GN chez les patients et nous avons appliqué ce modèle sur des données concernant plus de 21500 patients. Les facteurs influençant la transmission ont été étudiés par simulation de la diffusion du virus grippal dans une unité de soin à l’aide d’un modèle biomathématique. Nous montrons qu’il était difficile d’identifier les cas de grippe dans l’hôpital sans réalisation systématique d’un test de dépistage. Le risque pour le patient de présenter un syndrome grippal était 2 fois plus important à l’hôpital que dans la communauté. De plus ce risque était 5 à 35 fois plus élevé lorsqu’un patient était exposé à un autre patient ou à un soignant contagieux au cours de son séjour. La transmission de patient à patient semblait une voie de transmission importante. La démarche de ce travail pourrait être adaptée et l’outil statistique étendu à l’étude de la dynamique et du contrôle des infections nosocomialesThe consequences of outbreaks of nosocomial influenza (NI) for patients in terms of morbidity and mortality are an issue of concerned. However, clinical presentation of cases, frequency of infection, risk of infection among patients, transmission and the most adapted control measures remain poorly understood. An original analysis of the literature allowed synthesizing the knowledge on NI. Then on the basis of a prospective study conducted during 3 influenza seasons from 2004 to 2007, we report a description of clinical cases of NI observed at the Edouard Herriot hospital in Lyon. Then, we developed a statistical model to analyze the risk of NI among patients and we apply this model on data from over 21,500 patients. Factors influencing the transmission were studied by simulating the spread of influenza virus in a hospital unit using a mathematical model. We show that identifying cases of influenza in the hospital without a systematic virological screening is difficult. The risk for the patient to present influenza like illness was 2 times higher in hospital than in the community. Furthermore, the risk was 5 to 35 times higher when a patient was exposed to other contagious patients or health care workers during his hospitalization. Transmission from patient to patient seemed to be a major route of transmission. The approach used in this work could be adapted and the statistical tools could be extended to study of the dynamics and control of nosocomial infections
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Roberts, Craig William. "Immunological control of Toxoplama gondii infection." Thesis, University of Strathclyde, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389701.
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Rashleigh-Rolls, Rebecca M. "Hospital acquired infections : outbreaks and infection control interventions, a national descriptive survey." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/101494/1/Rebecca_Rashleigh-Rolls_Thesis.pdf.
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This study investigated hospital-acquired infection (HAI) across Australian public hospitals from January 2005 - December 2011. Specifically, outbreaks of HAI and infection control interventions (aimed at reducing HAI rates) were investigated. Outbreaks of HAI, with the most frequent pathogens being Norovirus and Vancomycin-resistant Enterococcus, occurred in the majority of hospitals. Further, a wide variety of infection control interventions were applied during the time-frame yet there was no standardised implementation approach. Rates of HAI appeared to be affected by the implementation of particular infection control interventions, either by reducing or increasing mean infection rates.
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Mtambo, Mkumbukwa Madundo Angelo. "Cryptosporidium infection in cats : epidemioloigy and cross transmission studies." Thesis, University of Glasgow, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384860.
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Brabant, Gilles. "L'infection bacterienne par transmission materno-foetale : depistage clinique et biologique." Lille 2, 1988. http://www.theses.fr/1988LIL2M106.
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Gea-Mallorquí, Ester. "HIV-2 infection in human primary macrophages." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066469.
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Les macrophages sont une cible cellulaire importante du VIH-1 et sont impliqués dans la propagation virale et la constitution du réservoir. Les patients infectés par le VIH-2 présentent un contrôle naturel de l'infection qui est généralement absent chez les patients infectés par le VIH-1. Nous avons étudié ici la relation entre les macrophages et le VIH-2 afin d'évaluer leur contribution à la physiopathologie de l'infection. L'assemblage de particules virales dans des macrophages dérivés de monocytes (MDM) infectés par le VIH-2 se fait au niveau de la membrane de compartiments internes semblables aux VCC documentés dans les MDM infectés par le VIH-1. Les VCC des MDM infectés par le VIH-1 et le VIH-2 partagent la même composition protéique, et la même morphologie. Contrairement à Gag du VIH-1, la protéine Gag du VIH-2 est absente du cytosol et presque exclusivement localisée dans les VCC, ce qui suggère que Gag du VIH-2 est rapidement transportée vers le VCC une fois synthétisée dans le cytosol. Les particules de VIH-2 produites de novo par les MDM peuvent mûrir, mais sont faiblement infectieuses et se transmettent inefficacement aux cellules T activés. Cette faible infectiosité n'est pas associée avec l'expression du facteur de restriction BST-2 et n'est pas non plus améliorée par une baisse des niveaux d'expression de BST-2 induite par Vpu. Nos données suggèrent que les macrophages infectés par le VIH-2 ne contribuent probablement pas à la production et à la dissémination du virus in vivo. Cependant, les macrophages infectés par le VIH-2 peuvent représenter une source potentielle d'antigènes viraux qui pourraient stimuler les réponses des cellules T spécifiques du virusMacrophages are an important cellular target of HIV-1 and are potentially involved in viral spreading and constitution of the viral reservoir. HIV-2-infected patients exhibit a natural virological control of the infection that is generally absent from HIV-1-infected patients. Here, we studied the relationship between macrophages and HIV-2 to approach their potential contribution to the physiopathology of HIV-2 infection. Viral particles assembly in HIV-2-infected monocyte-derived macrophages (MDMs) occurred at the limiting membrane of internal compartments similar to virus-containing compartments (VCCs) documented in HIV-1-infected MDMs. Indeed, VCCs from HIV-1 and HIV-2-infected MDMs shared protein composition, as seen by confocal microcopy, and morphology, as seen by electron microscopy. Strikingly, HIV-2 Gag was mostly absent from the cytosol and almost exclusively localized to the VCCs, whereas HIV-1 Gag was distributed in both locations, suggesting that HIV-2 Gag is rapidly transported to the VCC membranes once synthesized in the cytosol. HIV-2 particles produced de novo by MDMs can mature, but are poorly infectious and inefficiently transmitted to activated T cells. This low infectivity neither correlate with expression of the restriction factor BST-2, nor was improved by Vpu-induced down-modulation of BST-2 levels. Our data suggest that, HIV-2-infected macrophages are unlikely to contribute to viral production and dissemination in vivo. However, HIV-2-infected macrophages accumulate large amounts of intracellular virus that may represent a potential source of viral antigens that could stimulate virus specific T cell responses
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Burchell, Ann. "Human papillomavirus infection and transmission among couples through heterosexual activity." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40745.
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Human papillomavirus (HPV) is the most common sexually transmitted infection (STI). The vast majority of these infections clear spontaneously. The small proportion that persists may result in substantial morbidity and treatment costs. High oncogenic risk HPV (HR-HPV) types, including HPV-16 and 18, are recognised unequivocally as the main causal factor for cervical cancer, and may also cause other anogenital neoplasms and head and neck cancers. Infections with types that have low oncogenic risk (LR-HPV), such as HPV-6 and -11, are associated with benign lesions including genital warts. Many projections of the impact of the new HPV vaccines and screening technologies use dynamic transmission models which require sound estimates of the probability of transmission upon exposure. Furthermore, biological and practical limitations of the current vaccines require that we explore as many prevention options as possible. A critical research question is whether condoms provide protection. The main aims of the thesis were to characterize patterns of HPV infection among heterosexual couples in a new relationship, to identify risk factors for HPV infection, and to estimate HPV transmission probabilities per partnership and per coital act. I carried out a preliminary Monte Carlo simulation to estimate the probability of HPV transmission, then designed and conducted a study of heterosexual couples. The thesis objectives were addressed using baseline data from the ongoing HITCH Cohort Study (HPV Infection and Transmission among Couples through Heterosexual activity). The study population consists of young (aged 18-24) women attending a university or junior college (CEGEP) in Montreal and their male partners. Results from the simulation analysis suggested that HPV is highly transmissible, which was confirmed by the cross-sectional analysis of the HITCH study. Among the 263 couples enrolled between 05/2005 and 08/2008, HPV prevalence was 56% among women and men. In nearly two thLe virus du papillome humain (VPH) est l'infection transmissible sexuellement (ITS) la plus répandue. Une grande majorité des infections à VPH se résorbent spontanément. Cependant, la petite proportion d’infections à VPH persistantes peut avoir des coûts substantiels de traitement et de morbidité comme conséquence. Des génotypes de VPH à haut risque oncologique (HR-HPV), y compris HPV-16 et 18, sont identifiés sans équivoque comme facteur causal principal pour le cancer cervical, et peuvent également causer d'autres cancers anogénitaux, de la tête et du cou. Les infections avec des génotypes de VPH à bas risque oncologique (LR-HPV), comme HPV-6 et -11, sont associées aux lésions bénignes comprenant les verrues génitales. Plusieurs projections de l'impact des nouveaux vaccins de VPH et des techniques de dépistage utilisent des modèles de transmission dynamiques qui exigent des évaluations précises de la probabilité de transmission lors de l'exposition. En outre, les limitations biologiques et pratiques des vaccins courants exigent que nous explorions autant d'options de prévention que possibles. Une question critique de recherches est de savoir si les condoms assurent une protection. Les objectifs principaux de la thèse consistaient à caractériser des modèles typiques d’infection au VPH parmi les couples hétérosexuels dans une nouvelle relation, identifier des facteurs de risque pour l'infection au VPH, et estimer les probabilités de transmission du VPH par relation de couple et par acte coïtal. J'ai effectué une simulation préliminaire de Monte Carlo pour estimer la probabilité de transmission de VPH, puis j’ai conçu et entrepris une étude des couples hétérosexuels. Les objectifs de thèse ont été élaborés en utilisant les données de base de l'étude de cohorte HITCH (HPV Infection and Transmission among Couples through Heterosexual activity) qui se poursuit toujours. La population de l’étude est composée$
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Edwards, Charles T. T. "The evolution of HIV-1 during transmission and chronic infection." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410560.
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Mernelius, Sara. "Infection control of Staphylococcus aureus : spa typing to elucidate transmission." Doctoral thesis, Linköpings universitet, Institutionen för klinisk och experimentell medicin, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-116703.
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Staphylococcus aureus is a commensal of the human flora, primarily colonizing the anterior nares and throat, but it may also cause infections ranging from mild skin and soft tissue infections to severe diseases such as endocarditis and septicemia. S. aureus is also a major nosocomial problem increasing with the worldwide dissemination of methicillin-resistant S. aureus (MRSA). The main vector for bacterial cross-transmission in healthcare settings is the hands of healthcare workers (HCWs). No S. aureus was detected in the air in this thesis demonstrating that transmission through air is not important. Despite the fact that good compliance with hand hygiene is essential to prevent cross-transmission the compliance is generally less than 50 %. Gold standard to track bacterial transmission in healthcare settings has for long been pulsed-field gel electrophoresis (PFGE), a method that is labor- intensive, lacks consensus protocol and relies on semi-subjective analysis. Molecular typing by sequencing of the hypervariable part of the S. aureus protein A gene (spa typing) has overcome these problems and has shown promising results in epidemiological investigations. The aims of this thesis were to study bacterial transmission with S. aureus colonization of newborn infants as a model and to evaluate spa typing as a molecular tool. Additionally, the influence of compliance with hygiene guidelines on S. aureus transmission was assessed. Analysis of 280 MRSA isolates by spa typing revealed excellent typeability and epidemiological concordance and satisfactory discriminatory power. Additionally, spa typing was considered superior to PFGE thanks to its accessibility, ease of use and rapidity. Also, spa typing results are registered in a global database, facilitating inter-laboratory comparison. The prevalence of S. aureus ranged from 41 % to 66 % in the populations studied and males had the highest colonization rate. Throat was the premier colonization site for adults and transmission from individuals colonized in the throat only was documented, suggesting that throat cultures should be included in S. aureus screening programs. The umbilicus was the premier colonization site for newborn infants. Incubating the swabs in enrichment broth prior to plating increased the prevalence of S. aureus positive samples by 46 %, resulting in prevalence ranging from 51 % to 70 % in the populations studied. Thus enrichment prior to plating is necessary to determine more truthful S. aureus colonization rates. There were no indications of an institutional flora, as the colonization rates, spa type distribution and antibiotic resistance prevalence were similar among parents and HCWs. Direct observations and self-reporting by HCWs were both validated as tools for monitoring compliance with hygiene guidelines. The compliance with hygiene guidelines was significantly higher following a 10-point hygiene intervention as compared to baseline. The compliance was also higher three years after the intervention in three of four participating departments. These data show that it is possible to markedly improve the compliance with hygiene guidelines, but to achieve a long-term effect, continuous and varied reminders seems necessary. Both at baseline and following the intervention almost 60 % of the colonized infants were colonized with an S. aureus of the same spa type as isolated from their own family. At baseline approximately 25 % of the colonized infants received their S. aureus from non-family individuals, indicating transmission directly or indirectly from HCWs. Despite the improvement in compliance with barrier precautions from 41 % at baseline to 86 % following the hygiene intervention, the transmission from non-family did not decrease. This indicates that other factors may have a prominent impact on bacterial transmission. One factor might be the quality of hand hygiene technique which therefore needs to be studied further. However, to ensure patient safety it is still recommended that all HCWs comply with hygiene guidelines at all time.
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Yates, T. A. "Mycobacterium tuberculosis infection in Southern Africa : exploring patterns, locating transmission." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1532679/.
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Tuberculosis is a major cause of premature mortality. Communities in Southern Africa are disproportionately affected. A growing body of evidence suggests that recent transmission within households can explain only a limited proportion of tuberculosis disease. However, our understanding of where transmission between households occurs is limited. I undertook a systematic review and meta-analysis of molecular epidemiology studies that described rates of strain discordance in co-prevalent cases of tuberculosis resident in the same household. I also conducted a tuberculin school survey in 6-8 year old children in a rural community in Northern KwaZulu-Natal. These children were all registered in a household surveillance programme operated by the Africa Centre for Population Health. I found that, across a range of both high and low burden countries, co-prevalent cases of tuberculosis in the same household often have different strains of Mycobacterium tuberculosis. These molecular epidemiological data suggest, at least in some settings, that recent transmission within households may explain a modest proportion of tuberculosis disease. I estimated the annual risk of tuberculous infection to be approximately two percent in the community around the Africa Centre. I found weak evidence that exposure to HIV positive adults in the household was associated with Mycobacterium tuberculosis infection in children. I found no strong evidence associating use of specific indoor public spaces with Mycobacterium tuberculosis infection. Transmission between households is likely an important determinant of tuberculosis disease. Further research locating Mycobacterium tuberculosis transmission might enable TB control interventions to be better targeted.
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Lunn, Tamika J. "Flying-fox ecology and transmission dynamics of Hendra virus." Thesis, Griffith University, 2021. http://hdl.handle.net/10072/405630.
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Emerging zoonoses from wildlife present an increasing threat to global public health. Bats, in particular, host some of the most significant viral families to have emerged in recent decades, including coronaviruses, henipaviruses and filoviruses. Hendra virus (Genus: Henipavirus) is one such virus, which emerged in 1994 to cause lethal disease in horses and humans in eastern Australia. Increased incidence of spillover in recent decades has been concurrent with observations of dramatic ecological shifts in host flying-fox (Family: Pteropodidae) populations. Wide-spread land clearing in south-eastern Australia has compounded the effects of inter-annual climate cycles on flying-fox food availability, resulting in large-scale fragmentation and fissioning of flying-fox roosts. This has manifest as an increasing transition from a nomadic ecology, where individuals move across the landscape and form large roosts in response to ephemeral foraging opportunities, to residency, where individuals continuously occupy a single roost in an area with predictable (often exotic) food sources. Typical roosting habitat has shifted as a result, moving from forest remnants with dense roosting habitat, to urban areas with more sparse roosting habitat. Incidence of Hendra virus spillover has been correlated with the formation of these urban, continuously occupied population groups, suggesting that recent changes in host ecology may play a role in spillover dynamics. In order to predict and manage pathogen spillover from bats, we require a detailed understanding of infection dynamics within host bat populations.
In this thesis, I employ a multidisciplinary approach to investigate patterns and mechanistic drivers of Hendra virus infection dynamics in flying-fox populations, focusing on bat roosting structure as a driver of virus transmission. In Chapter 1, I describe the spillover process, and outline Hendra virus as a model to understanding spillover of bat-borne viruses. In Chapter 2, I present a spatio-temporal analysis of Hendra virus infection prevalence and excreted viral load from flying-fox populations, to estimate the dynamics of pathogen pressure over space and time, and to elaborate on possible drivers contributing to differences between roosts. This chapter presents a new longitudinal dataset of Hendra virus excretion dynamics, collected over 2.5 years (June 2017- December 2019), and comprising 4,343 samples from five main roost sites. A key finding of this chapter is that infection intensity is variable between roosts within the same regional area, suggesting that spillover risk is more nuanced than previously identified variation between broader regions.
To understand the ecological context for transmission in aggregative bat populations, I then assess spatio-temporal patterns of flying-fox density and distribution within roosts in Chapter 3. I present insights from detailed roost structure surveys, comprising a 13-month dataset from 2,522 spatially referenced roost trees across eight roost sites. A key finding is that tree structure density drives patterns of bat abundance within trees, with implications for transmission in emerging, urban roost types. I then integrate this ecological context into mathematical models of infection in Chapter 4, where I develop spatially explicit, compartmental models of bat roosts, and explore dynamics of infection invasion and spread. I utilise empirical data on roost tree structure and flying-fox aggregation from Chapter 3 to capture the spatial structure of roosts, and contrast scenarios of tree structure density that are representative of observed ecological shifts with urbanisation. In my last research chapter (Chapter 5), I propose a modelling framework to holistically integrate between-host and within-host contexts into these transmission dynamics. Specifically, I propose an alternative transmission model structure to allow the integration of dose-response relationships into epidemiological models. I also demonstrate how changes in the design and accessibility of dose-response experiments would facilitate integration into epidemiological modelling, to ultimately enable more realistic predictions of zoonotic transmission outcomes.
Collectively, insights from this thesis further our understanding of Hendra virus infection dynamics and spillover risk in a situation of changing host ecology. Beyond Hendra virus, the information presented highlights how aggregative spatial structuring of bats within roosts can add substantial heterogeneity to the contact structure of roost populations, with implications for models of bat-virus interactions. I present compelling evidence that spatial structure and flying-fox aggregation may be a missing piece to understanding differences in shedding intensity and spillover risk from roost sites across eastern Australia, particularly in the context of urbanisation and shifting roost structure. These insights will be relevant for modelling studies of other communally roosting species of zoonotic interest, as well as other emerging diseases linked with habitat modification and changing populations, including coronaviruses like SARS-CoV-2.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
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Cloutman-Green, E. A. "The role of the environment in transmission of healthcare associated infection." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1460498/.
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Infectious diseases are the current leading cause of human death and within this category nosocomial infections remain the most frequent complication of hospitalization. A range of infection prevention and control activities are employed to combat the selection and spread of these organisms. The principle components of which are: early identification of carriage/infection, patient isolation, improved hand hygiene, environmental control and good antimicrobial stewardship. In order to properly focus these interventions, it is essential to know how and when cross transmission has occurred. There is an ongoing debate about the role of the environment in the spread of healthcare associated infections and to what extent if any it acts as a potential vector for transmission. Within the healthcare setting patients spend a substantial amount of time surrounded by equipment and environmental surfaces that may be contaminated with microorganisms. In order to establish what role the environment could play, tracking the spread of organisms by molecular typing is key. The current methods used to do this are complex and often are only available at reference laboratories. This means that turnaround times are slow and only provide retrospective confirmation of cross-transmission events. Infection control interventions that can be used prior to receiving results play an important role. The selection and effectiveness of these interventions are often poorly supported by research studies, leading to problems with the introduction of evidence based practice and thus difficulty in selecting the most appropriate response to suspected cross transmission. This thesis aims to explore the role of the environment in cross transmission of infection by developing sampling methodologies to permit environmental surveillance, validating and developing typing techniques in order to establish epidemiological links between patients and environmental contamination and to evaluate infection control interventions to aid in prevention of cross transmission events.
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Gardon, Jacques. "Epidémiologie du virus HTLV-I/II au Cameroun : Transmission familiale : rôle des co-facteurs parasitaires." Montpellier 1, 1992. http://www.theses.fr/1992MON11033.
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Lindberg, Ann. "Epidemiology and eradication of bovine viral diarrhoea virus infections : studies on transmission and prenatal diagnosis of persistent infection /." Uppsala : Dept. of Ruminant Medicine and Veterinary Epidemiology, Swedish Univ. of Agricultural Sciences ([Institutionen för idisslarmedicin och epidemiologi], Sveriges lantbruksuniv.), 2002. http://epsilon.slu.se/v132.pdf.
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Osborne, Josephine Frances. "Transmission of powdery scab disease of potatoes by seed tubers." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311017.
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BORTUZZO, THIERRY. "Etude de la transmission verticale du virus de l'hepatite c." Clermont-Ferrand 1, 1993. http://www.theses.fr/1993CLF1MS23.
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BAAJ, BOUNYA. "Role des aliments comme vecteur de transmission des infections a aeromonas hydrophila." Strasbourg 1, 1995. http://www.theses.fr/1995STR15054.
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GIORGI, NICOLAS. "Transmission inter humaine de la fievre q a l'hopital de martigues." Aix-Marseille 2, 1994. http://www.theses.fr/1994AIX20106.
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Dumpis, Uga. "Epidemiological and molecular studies on chronic HBV infection in Gambian families." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340721.
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Tranchat, Corinne. "Réponse humorale dirigée contre le VIH-1 : au cours de l'évolution de la maladie, dans la transmission materno-foetale." Lyon 1, 1998. http://www.theses.fr/1998LYO1T119.
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Munywoki, Patrick Kiio. "Transmission of respiratory syncytial virus in households : who acquires infection from whom?" Thesis, Open University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607465.
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Households represent a setting of frequent and intense contacts and hence are conducive to the spread of respiratory viruses, such as respiratory syncytial virus (RSV). Infants are most vulnerable to severe RSV disease but a vaccine is oat yet available hence the need to explore alternate strategies of protecting them, Such strategies would require better understanding of who infects the infants. During the RSV season of200912010, we undertook a prospective study in rural Kenya involving 493 members of 47 households each with a child born after the preceding RSV epidemic and at least one elder sibling. Throughout the epidemic a nasopharyngeal swab (NPS) was collected every 3-4 days irrespective of symptoms, from all household members, and tested for a range of respiratory viruses including RSV using a molecular diagnostic assay. Partial sequencing of the attachment protein (G) gene from positive swabs was used to compare RSV strains within the household. In addition, once-a-week a specimen of oral fluid (OF) from around the gums was co11ected for RSV -specific antibodies screening and for assessment of sensitivity of the OF in detection of RSV using molecular diagnostics. This is the first prospective study to investigate introduction and transmission of RSV in families using molecular techniques over a complete RSV season. Analysis of RSV infection data is reported in this thesis with particular interest to identifying from where infants derive !.heir infection, estimating the duration of RSV shedding and identify factors influencing the recovery rates, and estimating parameters of RSV susceptibility and transmission probability. In addition, data on diagnostic performance of OF in detection of RSV by molecular methods is presented. A total of 16,924 NPS were collected, representing 86% of planned. RSV was detected in 40 (85%) households and 179 (36%) of the participants. In 28 of the 44 households with complete data, there was transmission of RSV to the infants experiencing their first epidemic. The probable source of RSV infection of the naive infants was a household member in at least 54% of the cases. Co-primary infection between a household member and the RSV -naive infant was ascribed in 4 of the cases. Older children were assigned the primary case for 11 (39%) of the infant cases and 10 (91 %) of these were attending school. The infants appeared to play a role transmitting the introduced infections to the other members of the household including to the mothers. These findings support vaccination strategies that target school age children and pregnant women. Both of these vaccination strategies can have profound benefits to RSV naive infants directly by augmenting neutralizing antibodies against RSV (immunization of the pregnant women) and indirectly by reducing transmission from siblings to RSV-naive infants. Results from this study provide increased confidence in the rationale for RSV vaccination of individuals who are not the key targets for protection
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Vink, Willem Daniel. "Investigating the epidemiology of bovine digital dermatitis : causality, transmission and infection dynamics." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432976.
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Pankajavally, Somanathan Pillai Smitha. "VIRAL AND HOST FACTORS AFFECTING INFECTION, PATHOGENICITY AND TRANSMISSION OF INFLUENZA VIRUSES." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250624574.
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Benhamou, Etty Lesprit Philippe. "Observation d'une transmission de tuberculose nosocomiale pulmonaire entre deux patients infectés par le VIH." Créteil : Université de Paris-Val-de-Marne, 2005. http://doxa.scd.univ-paris12.fr:80/theses/th0234851.pdf.
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Snow, Lucy Caroline. "The transmission ecology of lymphatic filariasis : infection processes in the mosquito vector and their implications for transmission and control." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414433.
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Gatei, Wangeci. "Epidemiology of intestinal parasites in relation to HIV infection in Western Kenya with special reference to Cryptosporidium." Thesis, University of Liverpool, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250233.
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Forrester, Marie Leanne. "Epidemic models and inference for the transmission of hospital pathogens." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16419/1/Marie_Forrester_Thesis.pdf.
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The primary objective of this dissertation is to utilise, adapt and extend current stochastic models and statistical inference techniques to describe the transmission of nosocomial pathogens, i.e. hospital-acquired pathogens, and multiply-resistant organisms within the hospital setting. The emergence of higher levels of antibiotic resistance is threatening the long term viability of current treatment options and placing greater emphasis on the use of infection control procedures. The relative importance and value of various infection control practices is often debated and there is a lack of quantitative evidence concerning their effectiveness. The methods developed in this dissertation are applied to data of methicillin-resistant Staphylococcus aureus occurrence in intensive care units to quantify the effectiveness of infection control procedures.
Analysis of infectious disease or carriage data is complicated by dependencies within the data and partial observation of the transmission process. Dependencies within the data are inherent because the risk of colonisation depends on the number of other colonised individuals. The colonisation times, chain and duration are often not visible to the human eye making only partial observation of the transmission process possible. Within a hospital setting, routine surveillance monitoring permits knowledge of interval-censored colonisation times. However, consideration needs to be given to the possibility of false negative outcomes when relying on observations from routine surveillance monitoring.
SI (Susceptible, Infected) models are commonly used to describe community epidemic processes and allow for any inherent dependencies. Statistical inference techniques, such as the expectation-maximisation (EM) algorithm and Markov chain
Monte Carlo (MCMC) can be used to estimate the model parameters when only partial observation of the epidemic process is possible. These methods appear well suited for the analysis of hospital infectious disease data but need to be adapted for short patient stays through migration. This thesis focuses on the use of Bayesian statistics to explore the posterior distributions of the unknown parameters. MCMC techniques are introduced to overcome analytical intractability caused by partial observation of the epidemic process. Statistical issues such as model adequacy and MCMC convergence assessment are discussed throughout the thesis.
The new methodology allows the quantification of the relative importance of different transmission routes and the benefits of hospital practices, in terms of changed transmission rates. Evidence-based decisions can therefore be made on the impact of infection control procedures which is otherwise difficult on the basis of clinical studies alone.
The methods are applied to data describing the occurrence of methicillin-resistant
Staphylococcus aureus within intensive care units in hospitals in Brisbane and London
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Forrester, Marie Leanne. "Epidemic models and inference for the transmission of hospital pathogens." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16419/.
Full textAbstract:
The primary objective of this dissertation is to utilise, adapt and extend current stochastic models and statistical inference techniques to describe the transmission of nosocomial pathogens, i.e. hospital-acquired pathogens, and multiply-resistant organisms within the hospital setting. The emergence of higher levels of antibiotic resistance is threatening the long term viability of current treatment options and placing greater emphasis on the use of infection control procedures. The relative importance and value of various infection control practices is often debated and there is a lack of quantitative evidence concerning their effectiveness. The methods developed in this dissertation are applied to data of methicillin-resistant Staphylococcus aureus occurrence in intensive care units to quantify the effectiveness of infection control procedures. Analysis of infectious disease or carriage data is complicated by dependencies within the data and partial observation of the transmission process. Dependencies within the data are inherent because the risk of colonisation depends on the number of other colonised individuals. The colonisation times, chain and duration are often not visible to the human eye making only partial observation of the transmission process possible. Within a hospital setting, routine surveillance monitoring permits knowledge of interval-censored colonisation times. However, consideration needs to be given to the possibility of false negative outcomes when relying on observations from routine surveillance monitoring. SI (Susceptible, Infected) models are commonly used to describe community epidemic processes and allow for any inherent dependencies. Statistical inference techniques, such as the expectation-maximisation (EM) algorithm and Markov chain Monte Carlo (MCMC) can be used to estimate the model parameters when only partial observation of the epidemic process is possible. These methods appear well suited for the analysis of hospital infectious disease data but need to be adapted for short patient stays through migration. This thesis focuses on the use of Bayesian statistics to explore the posterior distributions of the unknown parameters. MCMC techniques are introduced to overcome analytical intractability caused by partial observation of the epidemic process. Statistical issues such as model adequacy and MCMC convergence assessment are discussed throughout the thesis. The new methodology allows the quantification of the relative importance of different transmission routes and the benefits of hospital practices, in terms of changed transmission rates. Evidence-based decisions can therefore be made on the impact of infection control procedures which is otherwise difficult on the basis of clinical studies alone. The methods are applied to data describing the occurrence of methicillin-resistant Staphylococcus aureus within intensive care units in hospitals in Brisbane and London
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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.
Full textAbstract:
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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Pita, Ana Paula Gonçalves [UNESP]. "Efeito do método de esterilização e do tempo de uso sobre a eficiência de corte de fresas carbide." Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/97279.
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Considerando a importância do controle de infecção cruzada nos consultórios odontológicos, a vasta utilização de fresas de aço inoxidável/carbeto de tungstênio (carbide) e o receio dos cirurgiões dentistas em esterilizar esses instrumentos devido ao risco de danificá-los, o objetivo deste trabalho foi avaliar, comparativamente, o efeito de alguns métodos de esterilização, preconizados pela literatura e pelo Ministério da Saúde, sobre a eficiência de corte de fresas carbide. Os métodos de esterilização empregados foram: estufa, autoclave e forno de microondas; as marcas comerciais das fresas foram: Komet e S.S. White; e o tempo de aplicação desses instrumentos, em esmalte dental bovino, variou de 12 a 60 minutos. Para coleta dos dados, foram realizados testes gravimétricos e acompanhamento visual das fresas, após estas terem sido submetidas às diferentes condições experimentais. A análise dos resultados permitiu observar que ocorreu perda de eficiência de corte ao longo do tempo de utilização. Observou-se também que a partir de 60 minutos de aplicação em esmalte dental bovino, a eficiência de corte reduziu a 50% dos níveis iniciais. O efeito da esterilização foi diferente entre as marcas comerciais, sendo que cada uma se comportou de maneira diversa, em relação à quantidade de ciclos aplicados. Porém, a durabilidade total dos instrumentos não diferiu entre as marcas comerciais ou entre os métodos de esterilização aplicados. Considerando-se a importância e a responsabilidade do cirurgião dentista, quanto ao controle de infecção cruzada no ambiente do consultório odontológico, e comparando-se aos resultados relativos à durabilidade, evidenciados neste trabalho, pode-se afirmar que a utilização de métodos de esterilização, pode e deve ser adotada com segurança para esterilização de fresas carbide.
Dental burs inevitably become contaminated and the rotary cutting instruments as well as other instruments used in the treatment of patients must be sterilized after use by means of techniques that assure the asepsis, without damaging the instruments and its effectiveness, thus making possible its reuse. Concerning the importance of the control of infection crossed in the deontological clinicians further than the vast use of tungsten carbide burs and the distrust of the dentists in sterilized these instruments this study evaluated the effect of time usage (60 minutes) and sterilization (dry heat, vapor under pressure and energy for microwaves) over the cutting efficiency of carbide burs of two commercial brands. Gravimetrical tests were used for evaluation of the cutting efficiency and the visual acoompaniment of the burs was made along the test. It could be observed that the sterilization influenced in the cutting efficiency of the instruments, as well as the use time. From 60 minutes of application of the burs in the bovine dental enamel the cut efficiency were reduced at levels 50% minors when compared to the initial levels. These influences were different between instruments of the two commercial brands. Based on these results, it may be concluded that the effects of sterilization on cutting efficiency of carbide burs depends upon the composition of instruments and repeated cycles.
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Sundaravaradan, Vasudha. "Molecular Mechanism of HIV-1 Infection: Role of Viral and Host Determinants." Diss., Tucson, Arizona : University of Arizona, 2006. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1685%5F1%5Fm.pdf&type=application/pdf.
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Ejigu, Amsalework Ayele. "Mathematical modelling of HIV/AIDS transmission under treatment structured by age of infection." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6628.
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Thesis (MSc (Mathematical Sciences))--University of Stellenbosch, 2011.Includes bibliography.
ENGLISH ABSTRACT: This thesis takes into account the different levels of infectiousness of the human immunodeficiency virus (HIV) infected individuals throughout their period of infection. Infectiousness depends on the time since infection. It is high shortly after the infection occurs and then much lower for several years, and thereafter a higher plateau is reached before the acquired immunodeficiency syndrome (AIDS) phase sets in. In line with this, we formulated a mathematical model which is structured according to the age of infection. To understand the dynamics of the disease, we first discuss and analyse a simple model in which the age of infection is not considered, but progression of the HIV-AIDS transmission is taken into consideration by introducing three stages of infection. Analysis of these models tells us that the disease can be eradicated from the population only if on average one infected individual infects less than one person in his or her infectious period, otherwise the disease persists. To investigate the reduction of the number of infections caused by a single infectious individual to less than one, we introduce different treatment strategies for a model which depends on the age of infection, and we analyse it numerically. Current strategies amount to introducing treatment only at a late stage of infection when the infected individual has already lived through most of the infectious period. From our numerical results, this strategy does not result in eradication of the disease, even though it does reduce the burden for the individual. To eradicate the disease from the population, everyone would need to be HIV tested regularly and undergo immediate treatment if found positive.
AFRIKAANSE OPSOMMING: Hierdie tesis hou rekening met die verskillende aansteeklikheidsvlakke van die menslike immuniteitsgebreksvirus (MIV) deur besmette individue gedurende hulle aansteeklikheidstydperk. Die graad van aansteeklikheid hang af van die tydperk sedert infeksie. Dit is hoog kort nadat die infeksie plaasvind en daarna heelwat laer vir etlike jare, en dan volg n hoer plato voordat uiteindelik die Verworwe-Immuniteitsgebreksindroom (VIGS) fase intree. In ooreenstemming hiermee, formuleer ons n wiskundige model van MIV-VIGSoordrag met n struktureer waarin die tydperk sedert infeksie bevat is. Om die dinamika van die siekte te verstaan, bespreek en analiseer ons eers n eenvoudige model sonder inagneming van die tydperk sedert infeksie, terwyl die progressie van MIV-VIGS-oordrag egter wel in ag geneem word deur die beskouing van drie stadiums van infeksie. Analise van die modelle wys dat die siekte in die bevolking slegs uitgeroei kan word as elke besmette mens gemiddeld minder as een ander individu aansteek gedurende die tydperk waarin hy of sy self besmet is, anders sal die siekte voortduur. Vir die ondersoek oor hoe om die aantal infeksies per besmette individu tot onder die waarde van een te verlaag, beskou ons verskeie behandelingsstrategiee binne die model, wat afhang van die tydperk sedert infeksie, en ondersoek hulle numeries. Die huidige behandelingstrategiee kom neer op behandeling slegs gedurende die laat sta- dium van infeksie, wanneer die besmette individu reeds die grootste deel van die aansteeklikheidsperiode deurleef het. Ons numeriese resultate toon dat hierdie strategie nie lei tot uitroeiing van die siekte nie, alhoewel dit wel die las van die siekte vir die individu verminder. Om die siekte binne die bevolking uit te roei, sou elkeen gereeld vir MIV getoets moes word en indien positief gevind, dadelik met behandeling moes begin.
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Permanyer, Bosser Marc. "Characterization of the infection mechanism during cell-to-cell transmission of HIV-1." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/129101.
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La transmissió cèl·lula a cèl·lula del VIH-1 és un mecanisme altament eficient de disseminació viral, i la seva rellevància durant la difusió in vivo en els llocs actius de replicació, és a dir, en els teixits limfoides primaris i secundaris, sembla probable. La transmissió d'antígens del VIH de cèl·lules infectades a cèl·lules T CD4+ no infectades es produeix a través de contactes cèl·lula a cèl·lula que requereixen exclusivament de la interacció entre la proteïna de l'embolcall del VIH gp120 i el receptor CD4 per induir la captació endocítica de partícules virals en compartiments resistents a la tripsina en la cèl·lula diana. No obstant això, no ha estat completament estudiat el destí dels antígens del VIH prèviament transferits i si la internalització de partícules del VIH mitjançant endocitosi pot donar lloc a una infecció productiva. En aquest treball es mostra com IgGb12, un inhibidor de la unió del virus a CD4, va impedir la infecció de les cèl·lules diana carregades amb el VIH suggerint que les partícules virals endocitades van necessitar tornar a la superfície i arribar novament l'espai extracel·lular per interaccionar amb el receptor CD4 i iniciar una infecció productiva. Estudis previs realitzats amb microscòpia confocal van trobar que les proteïnes clatrina i dinamina colocalitzaven amb les partícules del VIH a la cèl·lula diana. Tot i això, dynasore, un inhibidor de la escissió endosomal no va impedir ni la captura de virus, ni la fusió del virus amb la cèl·lula ni la replicació del virus després de la transferència cèl·lula a cèl·lula de partícules del VIH suggerint que la maduració endosomal no és necessària per cap etapa del cicle d'infecció del VIH. D'altra banda, la quantificació de la producció de DNA total va indicar que tots els agents anti-VIH inhibien la transmissió de virus lliure o cèl·lula a cèl·lula amb una potència similar descartant que la transmissió cèl·lula a cèl·lula pogués contribuir a la persistència del virus durant la teràpia antiretroviral. Finalment, es va observar que la transferència cèl·lula a cèl·lula d'antígens del VIH-1 era depenent del grau de polimerització de la actina de les cèl·lules diana CD4+ T. D'aquesta manera, les diferències fenotípiques en l'actina cortical entre les cèl·lules CD4+ T naive i memòria van determinar la eficiència de la transferència d'antígens virals induint diferents susceptibilitats a la infecció per VIH-1. Els nostres resultats reforcen la idea de que, després dels contactes cèl·lula a cèl·lula, els virus endocitats poden representar un reservori de partícules virals itinerant capaç d'induir la trans-infecció de les cèl·lules adjacents, però no poden induir una replicació eficient a partir dels compartiments endosomals.La transmisión de célula a célula del VIH-1 es un mecanismo altamente eficiente de diseminación viral, y su relevancia durante la difusión in vivo en los sitios activos de replicación, es decir, en los tejidos linfoides primarios y secundarios, parece probable. La transmisión de antígenos del VIH de células infectadas a células T CD4+ no infectadas se produce a través de contactos célula a célula que requieren exclusivamente de la interacción entre la proteína de la envuelta del VIH gp120 y el receptor CD4 para inducir la captación endocítica de partículas virales en compartimientos resistentes a la tripsina en la célula diana. Sin embargo, no ha sido completamente estudiado el destino de los antígenos del VIH previamente transferidos y si la internalización de partículas del VIH mediante endocitosis puede dar lugar a una infección productiva. En este trabajo se muestra como IgGb12, un inhibidor de la unión del virus a CD4, impidió la infección de las células diana cargadas con el VIH sugiriendo que las partículas virales endocitadas necesitaron volver a la superficie y alcanzar nuevamente el espacio extracelular para interaccionar con el receptor CD4 e iniciar una infección productiva. Estudios previos realizados con microscopia confocal encontraron que las proteínas clatrina y dinamina colocalizaban con las partículas del VIH en la célula diana. A pesar de esto, dynasore, un inhibidor de la escisión endosomal no impidió ni la captura de virus, ni la fusión del virus con la célula ni la replicación del virus después de la transferencia célula a célula de partículas del VIH sugiriendo que la maduración endosomal no es necesaria para ninguna etapa del ciclo de infección del VIH. Por otra parte, la cuantificación de la producción de DNA total indicó que todos los agentes anti-VIH inhibían la transmisión de virus libre o célula a célula con una potencia similar descartando que la transmisión célula a célula pudiera contribuir a la persistencia del virus durante la terapia antiretroviral. Finalmente, se observó que la transferencia célula a célula de antígenos del VIH-1 era dependiente del grado de polimerización de la actina de las células diana CD4+ T. De esta manera, las diferencias fenotípicas en la actina cortical entre las células CD4+ T naive y memoria determinaron la eficiencia de la transferencia de antígenos virales induciendo distintas susceptibilidades a la infección por VIH-1. Nuestros resultados refuerzan la idea de que, después de los contactos célula a célula, los virus endocitados pueden representar un reservorio de partículas virales itinerante capaz de inducir la trans-infección de las células colindantes, pero no pueden inducir una replicación eficiente a partir de los compartimientos endosomales.
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Lee, Anne. "A Systematic Review of the Risk of HIV Transmission with Concurrent Schistosomiasis Infection." Thesis, The University of Arizona, 2018. http://hdl.handle.net/10150/626861.
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Traver, Brenna Elizabeth. "Infection Cycle, Transmission Mechanisms, and Management of Nosema ceranae in Apis mellifera Colonies." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/40261.
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Nosema ceranae is a recently described, widespread microsporidian parasite of Apis mellifera that has raised concerns as to whether it is contributing to increased colony losses. To better understand this parasite, investigations were made into the seasonality of infections, alternative transmission mechanisms, and potential control approaches. All studies used real-time PCR with specific primers and probes for N. ceranae, as well as traditional spore analysis. Monthly colony monitoring in Virginia showed that N. ceranae was present yearlong with the highest levels observed in April-June and lower levels through the fall and winter. There was no difference in infection levels among bees sampled from different areas of the hive regardless of the time of year. Additionally, N. ceranae infects all castes of the colony. Drones of different ages, including pupae, in-hive, and flying drones, were found to be infected at low levels with infections most prevalent during peak annual levels in April-June. Approximately 5% of flying drones had moderate to high levels of infection indicating that flying drones, which would be the most likely age group to drift, could assist in the horizontal transmission of N. ceranae both within and between apiaries. Immature and mated queens were also found to be infected at low levels. Infection in the ovaries and spermathecae suggests the possibility for vertical transmission. Finally, control of N. ceranae is thought to improve the health of bees and to reduce colony losses. Fall fumagillin treatments and winter stimulative pollen feeding were compared. Neither treatment significantly lowered N. ceranae levels in colonies sampled 3-6 months later, nor did they significantly improve colony survival. Due to the high cost of treatment and the time required, we do not recommend either treatment for N. ceranae infections during the fall. Colony winter losses due solely to N. ceranae seem unlikely because levels of N. ceranae were low. Impacts from N. ceranae infections were also minimal during the summer as productive colonies had some of the highest levels of infection. Although N. ceranae is prevalent throughout hives, it does not seem to be a major cause of colony losses.Ph. D.
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Muguruza, Laurence. "Etude descriptive et comparative de l'infection par le V. I. H en fonction du mode de contamination (Bordeaux, 1983 - 1990)." Bordeaux 2, 1991. http://www.theses.fr/1991BOR2M050.
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SAULPIC, LEMERLE JULIETTE. "L'encephalopathie precoce et severe au cours de l'infection a v. I. H. De l'enfant : etude retrospective de 42 cas d'encephalopathie precoce apres transmission materno-foetale." Paris, 1995. http://www.theses.fr/1995PA05C004.
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Garnett, Benjamin Thomas. "Behavioural aspects of bovine tuberculosis (Mycobacterium bovis) transmission and infection in badgers (Meles meles)." Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272050.
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Hayman, Anna. "The biodiversity of human immunodeficiency virus type 1 : evolution during primary infection and transmission." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252357.
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Feagins, Alicia R. "Foodborne Transmission and Molecular Mechanism of Cross-species Infection of Hepatitis E Virus (HEV)." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77266.
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Hepatitis E virus (HEV), the causative agent of hepatitis E, is an emerging virus of global distribution. At least four distinct genotypes of HEV exist worldwide: genotype 1 and 2 HEV strains are responsible for waterborne epidemics; genotype 3 and 4 HEV strains are responsible for sporadic occurrences of acute hepatitis E. Genotype 3 and 4 HEVs are zoonotic and have a more expanded host range than genotypes 1 and 2 which are restricted to humans. Genotype 3 and 4 HEV isolates obtained from animal tissues are genetically very similar, or identical in some cases, to human HEV recovered from hepatitis E patients. The objectives of this dissertation research were to assess the zoonotic foodborne transmission of HEV and elucidate the viral determinants of HEV host range. To determine the risk of HEV foodborne transmission, 127 packages of commercial pig liver were tested for HEV RNA. Eleven percent of them were positive for HEV RNA and the contaminating virus remained infectious. We also demonstrated that medium-to-rare cooking condition (56°C) does not completely inactivate HEV, although frying and boiling of the contaminated livers inactivated the virus. To reduce the risk of foodborne HEV transmission, commercial pig livers must be thoroughly cooked for consumption. To determine the host range of genotype 4 HEVs, pigs were inoculated with a genotype 4 human HEV. All pigs developed an active HEV infection indicating that genotype 4 human HEVs can cross species barriers and infect pigs. To identify viral determinant(s) of species tropism, ORF2 alone or in combination with its adjacent 5′ junction region (JR) and 3′ non-coding region (NCR), were swapped between genotypes 1 and 4, 3 and 4, and 1 and 3 to produce 5 chimeric viruses. Chimeric viruses containing ORF2 or JR+ORF2+3' NCR from genotype 4 human HEV in the backbone of genotype 3 swine HEV were viable in vitro and infectious in vivo. Chimeric viruses containing the JR+ORF2+3'NCR of genotypes 3 or 4 HEV in the backbone of genotype 1 human HEV were viable in vitro but non-infectious in pigs, suggesting that ORF1 may also be important for host range.Ph. D.
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Schmidt, Bey-Marrie. "Tuberculosis interventions to prevent transmission of infection in health care workers: a systematic review." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/19906.
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Background: Tuberculosis is a major cause of morbidity and mortality as an estimated 8.6 million people developed TB and 1.3 million died from the disease in 2012. The number of deaths is high given that TB can be prevented. Health care workers are an at - risk group, since they are frequently in contact with infectious patients and/or work with infectious products. The World Health Organisation has declared the importance of finding innovative tools and strategies to prevent TB and implementing them successfully, especially for those with a high risk of TB transmission. Methods: This systematic review aims to undertake a quantitative review of tuberculosis interventions for health care workers in health care settings, so as to assess whether these interventions are effective in reducing the transmission of tuberculosis infection and disease. We will preferably include experimental studies, such as, randomised - controlled trials, but observational studies, such as controlled before and after studies and cohort studies will also be included in the absence of randomised - controlled studies. We will search databases, such as Medline, Scopus, Trip, LILACS and various trial registries. A hand search of reference lists of identified articles, abstracts, conference proceedings and campaign materials will be performed. Grey literature sites will also be used for the search. Data will be extracted using a single form. The quality of each study will be assessed in terms of selection bias, performance bias, attrition bias and detection bias. Thereafter a meta - analysis will be produced and subgroups will be analysed according to the three intervention types. Clinical and statistical significance will be determined for the included studies, and descriptive narratives of heterogeneous studies will be written. Discussion: Our results will be useful to policy - makers and public health officials for the prioritisation of those interventions identified as effective and critical .
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Janus, Lydia Maria. "Transmission of minute virus of mice in mouse populations international PhD program "infection biology"." Giessen DVG-Service, 2009. http://d-nb.info/995700702/04.
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Wellensiek, Brian Philip. "Molecular Mechanisms of HIV-1 Infection: Viral and Host Determinants in Transmission and Pathogenesis." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/195132.
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HIV-1 vertical transmission is the predominant cause of AIDS in children. In addition, HIV-1 infected infants have a higher viral load and progress to AIDS more rapidly than infected adults. However, the molecular mechanisms of HIV-1 vertical transmission and pathogenesis are not known. Work performed in this laboratory has shown transmission of minor genotypes with R5 phenotypes, more heterogeneity associated with transmission and a higher replication and gene expression of HIV-1 in neonatal than adult cells. In this dissertation, I have made advancements by characterizing the HIV-1 gag nucleocapsid gene, that plays a pivotal role in HIV-1 lifecycle, from six mother-infant pairs and found that there was a low degree of viral heterogeneity and a high conservation of functional domains for biological activity and CTL response. With respect to differential mechanisms of HIV-1 infection in neonatal vs. adults cells, 468 HIV-1 integration sites were characterized in the T-lymphocytes and monocyte-derived-macrophages from 5 donors of infant and adult blood. Several functional classes of genes were identified by gene ontology to be over represented, including genes for cellular components, maintenance of intracellular environment, enzyme regulation, cellular metabolism, catalytic activity and cation transport. Numerous potential transcription factors binding sites at the site of integration were identified. Furthermore, the genes at integration site, transcription factors potentially binding upstream of HIV-1 promoter and factors that assist HIV-1 integration were found to be expressed at higher levels in cord than adult cells. These results may help explain a higher HIV-1 gene expression and replication in cord compared with adult cells. Finally, I have also made progress in the development of new and novel antivirals by showing that CD4-mimetic miniproteins significantly inhibited HIV-1 entry and replication in T-cell lines and primary blood mononuclear cells. In addition, several compounds from the crude extracts of endophytic fungi found in desert plants were able to inhibit HIV-1 replication in T-cell lines. Taken together, the results from this dissertation provide new insights into understanding the mechanisms of HIV-1 vertical transmission and HIV-1 gene expression and replication in infants, as well as provide new possibilities for anti-retroviral drug development.
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Clancy, Chad S. "Male Reproductive Infection and Sexual Transmission of Zika Virus in an Immunocompromised Mouse Model." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7478.
Full textAbstract:
Zika virus (ZIKV) is a sexually transmitted viral infection most frequently transmitted by mosquitoes. The source of infectious virions in the male reproductive tract has yet to be elucidated. The goals of the studies included developing and characterizing two mouse models for reproductive transmission studies and demonstration of sexual transmission of virus via artificial insemination. The mouse strains used in the study lacked receptors to interferon molecules, key signaling proteins of the host immune response. Inflammation severity was assessed during acute disease, 5-11 days after infection using a novel histopathology grading system. ZIKV proteins and genome were initially detected in epididymal epithelial cells in males. Inflammation was first observed in the epididymis and progressed to the testicle in both AG129 and Ifnar-/- males. Infection of Ifnar-/- mice may better recapitulate Zika virus pathology in humans due to milder histopathologic lesions, the presence of histologically normal sperm in epididymal tubules, and an ability to survive the acute phase of disease. In further studies, male Ifnar-/- mice were challenged subcutaneously with ZIKV. Artificial insemination fluid derived from experimentally infected males showed positive sexual transmission at 7 days post infection (DPI) but not 35 or 70 DPI. These studies show passage of virus from epididymal flush and seminal plasma to females via insemination during acute ZIKV disease in males and provides a model for sexual transmission of ZIKV.
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Davis, Adam James. "Transcriptional analysis of human immunodeficiency virus type 1 infection following cell-to-cell transmission /." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phd2609.pdf.
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Gisserot, Olivier. "Infection par le virus de l'immunodéficience humaine et hétérosexualité : à propos de 206 cas observés au CHU de Bordeaux (GECSA 1985-1991)." Bordeaux 2, 1991. http://www.theses.fr/1991BOR2M217.
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