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1
Kobayashi, T., T. Sakurai, M. Sakakibara, and T. Watanabe. "Multiple origins of outbreak populations of a native insect pest in an agro-ecosystem." Bulletin of Entomological Research 101, no. 3 (December 21, 2010): 313–24. http://dx.doi.org/10.1017/s0007485310000490.
Повний текст джерелаАнотація:
AbstractNative insects can become epidemic pests in agro-ecosystems. A population genetics approach was applied to analyze the emergence and spread of outbreak populations of native insect species. Outbreaks of the mirid bug, Stenotus rubrovittatus, have rapidly expanded over Japan within the last two decades. To characterize the outbreak dynamics of this species, the genetic structure of local populations was assessed using polymorphisms of the mtDNA COI gene and six microsatellite loci. Results of the population genetic analysis suggested that S. rubrovittatus populations throughout Japan were genetically isolated by geographic distance and separated into three genetic clusters occupying spatially segregated regions. Phylogeographic analysis indicated that the genetic structure of S. rubrovittatus reflected post-glacial colonization. Early outbreaks of S. rubrovittatus in the 1980s occurred independently of genetically isolated populations. The genetic structure of the populations did not fit the pattern of an outbreak expansion, and therefore the data did not support the hypothesis that extensive outbreaks were caused by the dispersal of specific pestiferous populations. Rather, the historical genetic structure prior to the outbreaks was maintained throughout the increase in abundance of the mirid bug. Our study indicated that changes in the agro-environment induced multiple outbreaks of native pest populations. This implies that, given suitable environmental conditions, local populations may have the potential to outbreak even without invasion of populations from other environmentally degraded areas.
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Scandol, JP, and MK James. "Hydrodynamics and larval dispersal: a population model of Acanthaster planci on the Great Barrier Reef." Marine and Freshwater Research 43, no. 3 (1992): 583. http://dx.doi.org/10.1071/mf9920583.
Повний текст джерелаАнотація:
This paper presents results of a modelling study of the large-scale population dynamics of Acanthaster planci in the central Great Barrier Reef. Dispersal patterns generated by larval transport models are used to drive the simulation. Population flow through the reef matrix during outbreaks is simulated by using an elementary representation of the starfish life cycle. Features of the results include the following: (I) Population patterns generated by the model are consistent with observations of starfish outbreaks. (2) The overall impact of starfish populations undergoing an outbreak on the reef system decreases with a southward shift in the location of initial outbreaks. (3) Within the central Great Barrier Reef, outbreak populations of starfish generally occur more frequently on the inner- and central-matrix reefs than on the outer-matrix reefs.
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Larroque, Jeremy, Julian Wittische, and Patrick M. A. James. "Quantifying and predicting population connectivity of an outbreaking forest insect pest." Landscape Ecology 37, no. 3 (December 23, 2021): 763–78. http://dx.doi.org/10.1007/s10980-021-01382-9.
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Abstract Context Dispersal has a key role in the population dynamics of outbreaking species such as the spruce budworm (Choristoneura fumiferana) as it can synchronize the demography of distant populations and favor the transition from endemic to epidemic states. However, we know very little about how landscape structure influences dispersal in such systems while such knowledge is essential for better forecasting of spatially synchronous population dynamics and to guide management strategies. Objectives We aimed to characterize the spatial environmental determinants of spruce budworm dispersal to determine how these features affect outbreak spread in Quebec (Canada). We then apply our findings to predict expected future landscape connectivity and explore its potential consequences on future outbreaks. Methods We used a machine-learning landscape genetics approach on 447 larvae covering most of the outbreak area and genotyped at 3562 SNP loci to identify the main variables affecting connectivity. Results We found that the connectivity between outbreak populations was driven by the combination of precipitation and host cover. Our forecasting suggests that between the current and next outbreaks, connectivity may increase between Ontario and Quebec, and might decrease in the eastern part, which could have the effect of limiting outbreak spread from Ontario and Quebec to the eastern provinces. Conclusions Although we did not identify any discrete barriers, low connectivity areas might constrain dispersal in the current and future outbreaks and should in turn, be intensively monitored. However, continued sampling as the outbreak progresses is needed to confirm the temporal stability of the observed patterns.
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Rabilloud, Muriel, Benjamin Riche, Jean François Etard, Mad-Hélénie Elsensohn, Nicolas Voirin, Thomas Bénet, Jean Iwaz, René Ecochard, and Philippe Vanhems. "COVID-19 outbreaks in nursing homes: A strong link with the coronavirus spread in the surrounding population, France, March to July 2020." PLOS ONE 17, no. 1 (January 7, 2022): e0261756. http://dx.doi.org/10.1371/journal.pone.0261756.
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Background Worldwide, COVID-19 outbreaks in nursing homes have often been sudden and massive. The study investigated the role SARS-CoV-2 virus spread in nearby population plays in introducing the disease in nursing homes. Material and methods This was carried out through modelling the occurrences of first cases in each of 943 nursing homes of Auvergne-Rhône-Alpes French Region over the first epidemic wave (March-July, 2020). The cumulative probabilities of COVID-19 outbreak in the nursing homes and those of hospitalization for the disease in the population were modelled in each of the twelve Départements of the Region over period March-July 2020. This allowed estimating the duration of the active outbreak period, the dates and heights of the peaks of outbreak probabilities in nursing homes, and the dates and heights of the peaks of hospitalization probabilities in the population. Spearman coefficient estimated the correlation between the two peak series. Results The cumulative proportion of nursing homes with COVID-19 outbreaks was 52% (490/943; range: 22–70% acc. Département). The active outbreak period in the nursing homes lasted 11 to 21 days (acc. Département) and ended before lockdown end. Spearman correlation between outbreak probability peaks in nursing homes and hospitalization probability peaks in the population (surrogate of the incidence peaks) was estimated at 0.71 (95% CI: [0.66; 0.78]). Conclusion The modelling highlighted a strong correlation between the outbreak in nursing homes and the external pressure of the disease. It indicated that avoiding disease outbreaks in nursing homes requires a tight control of virus spread in the surrounding populations.
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Johns, R. C., L. Flaherty, D. Carleton, S. Edwards, A. Morrison, and E. Owens. "Population studies of tree-defoliating insects in Canada: a century in review." Canadian Entomologist 148, S1 (January 25, 2016): S58—S81. http://dx.doi.org/10.4039/tce.2015.69.
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AbstractOur review highlights research during the past century focussed on the population ecology of outbreak-prone insect defoliators in Canadian forests. Based on reports from national and provincial surveys that began in the 1930s, there have been at least 106 insect defoliators reported to outbreak, most of which are native Lepidoptera, Hymenoptera (sawflies), or Coleoptera (in order of frequency from most to least). Studies comparing life-history traits of outbreak versus non-outbreak species to better understand why certain species are more outbreak-prone indicate several traits especially common among outbreak species, including egg clustering and aggregative larval feeding. There have been at least 50 time-series studies examining the spatiotemporal population behaviour of 12 major defoliator species. These studies provide evidence for both regular periodicity and spatial synchrony of outbreaks for most major species. Life-table studies seeking to understand the agents causing populations to fluctuate have been carried out for at least seven outbreak species, with the majority identifying natural enemies (usually parasitoids) as the major driver of outbreak collapse. Our review concludes with several case studies highlighting the impact and historical underpinnings of population studies for major defoliator species and a discussion of potential avenues for future research.
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STENE-JOHANSEN, K., P. A. JENUM, T. HOEL, H. BLYSTAD, H. SUNDE, and K. SKAUG. "An outbreak of hepatitis A among homosexuals linked to a family outbreak." Epidemiology and Infection 129, no. 1 (August 2002): 113–17. http://dx.doi.org/10.1017/s0950268802007069.
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Several outbreaks of hepatitis A occurred in Norway in 1995–8. Molecular epidemiology was used to follow the spread of hepatitis A virus in the population. Distinct strains of hepatitis A virus (HAV) were detected by reverse transcriptase–polymerase chain reaction (RT–PCR) and subsequent sequencing in serum from patients in different communities at risk of infection. Two HAV strains were detected in an outbreak among 26 men having sexual contact with other men. One of these strains was also detected in a geographically limited family outbreak. The family outbreak was first believed to be acquired abroad. The sequence information linked the two outbreaks, and epidemiological and serological analyses revealed the transmission route. This study demonstrates the importance of molecular epidemiology in outbreak investigation, surveillance and monitoring of hepatitis A in the population.
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Johns, Robert C., Joseph J. Bowden, Drew R. Carleton, Barry J. Cooke, Sara Edwards, Erik J. S. Emilson, Patrick M. A. James, et al. "A Conceptual Framework for the Spruce Budworm Early Intervention Strategy: Can Outbreaks be Stopped?" Forests 10, no. 10 (October 16, 2019): 910. http://dx.doi.org/10.3390/f10100910.
Повний текст джерелаАнотація:
The spruce budworm, Choristoneura fumiferana, Clem., is the most significant defoliating pest of boreal balsam fir (Abies balsamea (L.) Mill.) and spruce (Picea sp.) in North America. Historically, spruce budworm outbreaks have been managed via a reactive, foliage protection approach focused on keeping trees alive rather than stopping the outbreak. However, recent theoretical and technical advances have renewed interest in proactive population control to reduce outbreak spread and magnitude, i.e., the Early Intervention Strategy (EIS). In essence, EIS is an area-wide management program premised on detecting and controlling rising spruce budworm populations (hotspots) along the leading edge of an outbreak. In this article, we lay out the conceptual framework for EIS, including all of the core components needed for such a program to be viable. We outline the competing hypotheses of spruce budworm population dynamics and discuss their implications for how we manage outbreaks. We also discuss the practical needs for such a program to be successful (e.g., hotspot monitoring, population control, and cost–benefit analyses), as well as the importance of proactive communications with stakeholders.
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Imholt, C., A. Esther, J. Perner, and J. Jacob. "Identification of weather parameters related to regional population outbreak risk of common voles (Microtus arvalis) in Eastern Germany." Wildlife Research 38, no. 7 (2011): 551. http://dx.doi.org/10.1071/wr10196.
Повний текст джерелаАнотація:
Context Common vole (Microtus arvalis) populations can increase to several thousand individuals per hectare during outbreaks. In central Europe such outbreaks usually extend across large areas but there can be significant regional differences in outbreak intensity, general outbreak risk and associated crop damage. Aims We tested whether weather parameters can be used to explain the regional variability in outbreak risk of common voles in an area of Eastern Germany where common vole outbreaks are common. Method Suitable weather parameters were identified by principal component analysis (PCA). Time series of common vole abundance from 50 locations across 36 500 km2 sampled in 1973–97 were related to weather parameters selected by PCA and multiple linear regression. A hierarchical cluster analysis was used on relevant weather parameters to display the temporal and spatial variability in vole abundance. An overlay of risk class transformed abundances allowed for the identification of appropriate threshold values to define vole outbreaks. Key results Weather parameters were closely related to the variation in regional outbreak risk of common voles. Mostly weather parameters in winter and early spring were identified to be highly important. All risk thresholds tested revealed similar patterns for the distribution of risk classes across locations and years. While most years of very low or very high outbreak risk clustered well according to weather parameters, some cases of medium risk classes did not cluster well. Conclusions Weather parameters especially in winter and early spring are related to common vole outbreak risk in the following autumn. This is the case for extremely high and low outbreak risks and is largely independent of the choice of particular threshold values for outbreak risk. Implications Weather parameters could be used to develop automated forecast systems at the spatial resolution of single weather stations. Combined with other parameters that are easily available, such as information on soil characteristics, such forecasts might be as reliable as more complex biological models developed in the past.
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Sudarsono, Hamim. "HAMA BELALANG KEMBARA (LOCUSTA MIGRATORIA MANILENSIS MEYEN): FAKTA DAN ANALISIS AWAL LEDAKAN POPULASI DI PROVINSI LAMPUNG." Jurnal Hama dan Penyakit Tumbuhan Tropika 3, no. 2 (September 3, 2003): 51–56. http://dx.doi.org/10.23960/j.hptt.2351-56.
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Migratory locust (Locusta migratoria manilensis Meyen) : Preliminary facts and analyzes on the population outbreaks in Lampung Province. The migratory locust (locally known as belalang kembara), Locusta migratoria manilensis Meyen (Orthoptera: Acrididae), has become a major insect pest in Lampung in recent years since its outbreak in 1998. Thousand hectares of agricultural fields were severely destroyed by the locust populations during the course of the outbreak. Local as well as national government were caught in surprised by the population upsurge with little information and technology available for controlling the pest. First presence of locust population was recorded in Kecamatan Pakuan Ratu in 1990. Area damage in the first year was ca. 60 ha. The population grew steadily over the years and reached its peak in April-May of 1998 when thousands of corn and rice fields were severely damaged. Country roads and fields were filled with millions of locust nymphs. Records of locust attacks during preliminary outbreaks from 1990 to 1998 also indicated that the insect started its outbreak from the same areas during those years, i.e. North Lampung District and northern Tulang Bawang District (two of the outmost northern of Lampung Province). Insect pest control experts were very concerned that the locust has established its populations in the region and could cause significant loss in the upcoming years. Control strategy and techniques based on the insect biology and population dynamics, therefore, should be explored and developed to manage future outbreaks. This paper discusses and analyzes preliminary facts and information on the migratory locust and possible strategies that could be implemented for managing the locust.
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Al-Abdullah, Nabeela Abdullah. "Measles outbreak amongst Manymar population of Jeddah City, Saudi Arabia." International Journal Of Community Medicine And Public Health 5, no. 7 (June 22, 2018): 2657. http://dx.doi.org/10.18203/2394-6040.ijcmph20182420.
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Background: Worldwide efforts for measles elimination are made possible due to the availability of a highly effective measles vaccine. In spite of a highly vaccinated population, an outbreak of measles has occurred in Jeddah province of Saudi Arabia, from January to February 2018.Methods: An outbreak investigation was conducted to describe the epidemiology of the outbreak. A performance audit of the control measures taken by the primary healthcare team was carried out in accordance with the World Health Organization (WHO) standards.Results: Of the 31 cases reported, the patient’s ages range from 1–9 years with an average age of 6 (±2) years. The index case was a 9 year old male. The performance indicator target for outbreak control measures was achieved. Ninety percent of the cases were investigated within 48 hours. Specimens such as serum blood and nasopharyngeal swabs were collected within the optimal period to test for measles IgG and IgM antibody.Conclusions: This outbreak demonstrates the increased susceptibility of unvaccinated children aged 6–11 months. To prevent possible future outbreaks, community awareness through educational campaigns, a review of children’s vaccination records, enhanced community surveillance and a measles ‘catch-up’ mass immunization campaign to interrupt chains of transmission are necessary.
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REYES-SILVEYRA, JORGE, ARMIN R. MIKLER, JUSTIN ZHAO, and ANGEL BRAVO-SALGADO. "MODELING INFECTIOUS OUTBREAKS IN NON-HOMOGENEOUS POPULATIONS." Journal of Biological Systems 19, no. 04 (December 2011): 591–606. http://dx.doi.org/10.1142/s0218339011004007.
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Emerging diseases, novel strains of reemerging diseases, and bioterrorism threats necessitate the development of computational models that can supply health care providers with tools to facilitate analysis and simulation of the progression of infectious diseases in a population. Most computational models assume homogeneous mixing within populations. However, a more realistic approach to the simulation of infectious disease outbreaks includes the stratification of populations in which the interactions between individuals are affinity-based. To examine the effects of heterogeneous populations on the outbreak dynamics, we developed a hybrid model that includes clustered individuals which represent differentiated populations. This facilitates the study of the effects of distinct behavioral properties on the dynamics of an infectious disease epidemic. Our results indicate that non-uniform interactions and affinity-driven behavior can drastically change the outbreak dynamics in the population.
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Andersson, Y. "A Waterborne Disease Outbreak." Water Science and Technology 24, no. 2 (July 1, 1991): 13–15. http://dx.doi.org/10.2166/wst.1991.0021.
Повний текст джерелаАнотація:
In Sweden 63 waterborne outbreaks occurred during the last 10 years. Even if these outbreaks include smaller family incidents, at least 10 community outbreaks involved more than 1,000 victims each, the largest being in the city of Boden in 1988. This outbreak hit 41% of the population with gastrointestinal symptoms and was preceded by the distribution of virtually untreated, fecally contaminated river water due to a transitory absence of chlorination.
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Serrana, Joeselle M., Naoto Ishitani, Thaddeus M. Carvajal, Billy Joel M. Almarinez, Alberto T. Barrion, Divina M. Amalin, and Kozo Watanabe. "Unraveling the Genetic Structure of the Coconut Scale Insect Pest (Aspidiotus rigidus Reyne) Outbreak Populations in the Philippines." Insects 10, no. 11 (October 26, 2019): 374. http://dx.doi.org/10.3390/insects10110374.
Повний текст джерелаАнотація:
Despite the fact that massive outbreaks of the coconut scale insect pest, Aspidiotus rigidus Reyne (Hemiptera: Diaspididae) are inflicting significant economic losses to the Philippines’ coconut industry, little is known about the population and dispersal history of this invasive pest in the country. Here, we examined the genetic diversity, structure and demographic history of A. rigidus sampled from localities with reported outbreaks from 2014 to 2017. We analyzed the genetic structure of the outbreak populations using mitochondrial COI and nuclear EF-1α markers. Both markers and all methods of population genetic structure analyses indicate clear differentiation among the A. rigidus populations separating the north from the southern regions of the Philippines. Very low or no genetic differentiation was observed within and amongst the populations per geographic region indicating two unrelated outbreak events of the pest originating from two genetically uniform populations isolated in each respective region. Historical data supports the resurgence of an established A. rigidus population in the south which could have been driven by sudden climatic changes or human-induced habitat imbalance. Our study provides valuable information on the genetic differentiation of the two A. rigidus groups that would be useful for developing and implementing biological control strategies against this pest in the Philippines.
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Shegelski, Victor A., Erin O. Campbell, Kirsten M. Thompson, Caroline M. Whitehouse, and Felix A. H. Sperling. "Source and spread dynamics of mountain pine beetle in central Alberta, Canada." Canadian Entomologist 153, no. 3 (February 24, 2021): 314–26. http://dx.doi.org/10.4039/tce.2020.83.
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AbstractThe mountain pine beetle (Dendroctonus ponderosae Hopkins) (Coleoptera: Curculionidae) is a significant destructive force in the pine forests of western Canada and has the capacity to spread east into a novel host tree species, jack pine (Pinaceae). New populations have been documented in central Alberta, Canada, but the source populations for these outbreaks have yet to be identified. In this study, we use genetic data to identify parent populations for recent outbreak sites near Slave Lake, Lac La Biche, and Hinton, Alberta. We found the northern population cluster that entered Alberta near Grande Prairie was the source of the most eastern established population near Lac La Biche, and the range expansion to this leading-edge population has been too rapid to establish evidence of population structure. However, some dispersal from a population in the Jasper and Hinton area has been detected as far north and east as Slave Lake, Alberta. We also identified two potential source populations for the current outbreak in Hinton: most beetles appear to be from Jasper National Park, Alberta, but some also originated from the northern population cluster. These findings demonstrate the dynamic dispersal capabilities of mountain pine beetle across the Alberta landscape and the potential hazard of increased dispersal to newly established leading-edge populations.
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Meshkova, Valentyna, Serhii Nazarenko, and Maryna Kolienkina. "Diprion pini L. (Hymenoptera, Symphyta, Diprionidae) population dynamics in the Low Dnieper region." Folia Forestalia Polonica 61, no. 1 (March 1, 2019): 22–29. http://dx.doi.org/10.2478/ffp-2019-0002.
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Abstract Pine sawflies (Hymenoptera, Symphyta, Diprionidae) are the most spread foliage browsing insects of pine forests in Europe, especially monovoltinous European pine sawfly Neodiprion sertifer (Geoffroy, 1785) and common pine sawfly Diprion pini (Linnaeus, 1758), which develops in one or two generations per year depending on weather. The outbreaks of both pine sawflies are the most frequent and intensive in the Steppe zone of Ukraine, especially in the Low Dnieper region, where pine forest (Pinus sylvestris Linnaeus and Pinus pallasiana D. Don) was planted on moving sands in the sixties of the 20th century. This research is aimed at the evaluation of the parameters for D. pini outbreak dynamics in the Low Dnieper region. Outbreak severity, specific foci area and mean score of stand threat by D. pini were evaluated from the regional statistical reports. In the regional scale for 1979–2017, notable outbreaks of D. pini were registered in 1982, 1993, 2002, 2006 and 2017. An interval between maximums was from 4 to 11 years, in average 9 years. The growth of foci area in 1979–1998 as compared to 1999–2017 as well as correlation between pine stand area and annual area of this pest’s foci in different forests was not statistically significant. Graphical analysis of dynamics of D. pini focal area for 2010–2017 was done based on individual threat levels. Our study confirms the fact of three outbreaks for this period in three forest and hunting enterprises (FHE), two outbreaks in one FHE and one outbreak in one FHE. An interval between the outbreaks makes three or six years. The causes of such shortening of interval are discussed.
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Matthews, L., P. G. Coen, J. D. Foster, N. Hunter, and M. E. J. Woolhouse. "Population dynamics of a scrapie outbreak." Archives of Virology 146, no. 6 (June 1, 2001): 1173–86. http://dx.doi.org/10.1007/s007050170113.
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Ratho, R. K., Baijayantimala Mishra, Tarundeep Singh, Pooja Rao, and Rajesh Kumar. "Measles outbreak in a migrant population." Indian Journal of Pediatrics 72, no. 10 (October 2005): 893–94. http://dx.doi.org/10.1007/bf02731127.
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Pananos, A. Demetri, Thomas M. Bury, Clara Wang, Justin Schonfeld, Sharada P. Mohanty, Brendan Nyhan, Marcel Salathé, and Chris T. Bauch. "Critical dynamics in population vaccinating behavior." Proceedings of the National Academy of Sciences 114, no. 52 (December 11, 2017): 13762–67. http://dx.doi.org/10.1073/pnas.1704093114.
Повний текст джерелаАнотація:
Vaccine refusal can lead to renewed outbreaks of previously eliminated diseases and even delay global eradication. Vaccinating decisions exemplify a complex, coupled system where vaccinating behavior and disease dynamics influence one another. Such systems often exhibit critical phenomena—special dynamics close to a tipping point leading to a new dynamical regime. For instance, critical slowing down (declining rate of recovery from small perturbations) may emerge as a tipping point is approached. Here, we collected and geocoded tweets about measles–mumps–rubella vaccine and classified their sentiment using machine-learning algorithms. We also extracted data on measles-related Google searches. We find critical slowing down in the data at the level of California and the United States in the years before and after the 2014–2015 Disneyland, California measles outbreak. Critical slowing down starts growing appreciably several years before the Disneyland outbreak as vaccine uptake declines and the population approaches the tipping point. However, due to the adaptive nature of coupled behavior–disease systems, the population responds to the outbreak by moving away from the tipping point, causing “critical speeding up” whereby resilience to perturbations increases. A mathematical model of measles transmission and vaccine sentiment predicts the same qualitative patterns in the neighborhood of a tipping point to greatly reduced vaccine uptake and large epidemics. These results support the hypothesis that population vaccinating behavior near the disease elimination threshold is a critical phenomenon. Developing new analytical tools to detect these patterns in digital social data might help us identify populations at heightened risk of widespread vaccine refusal.
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Martinez-Sañudo, Isabel, Corrado Perin, Giacomo Cavaletto, Giacomo Ortis, Paolo Fontana, and Luca Mazzon. "Studying genetic population structure to shed light on the demographic explosion of the rare species Barbitistes vicetinus (Orthoptera, Tettigoniidae)." PLOS ONE 16, no. 5 (May 6, 2021): e0250507. http://dx.doi.org/10.1371/journal.pone.0250507.
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Insect outbreaks usually involve important ecological and economic consequences for agriculture and forestry. The short-winged bush-cricket Barbitistes vicetinus Galvagni & Fontana, 1993 is a recently described species that was considered rare until ten years ago, when unexpected population outbreaks causing severe defoliations across forests and crops were observed in north-eastern Italy. A genetic approach was used to analyse the origin of outbreak populations. The analysis of two mitochondrial regions (Cytochrome Oxidase I and II and 12S rRNA-Control Region) of 130 samples from the two disjunct ranges (Euganean and Berici Hills) showed high values of haplotype diversity and revealed a high geographical structure among populations of the two ranges. The high genetic variability observed supports the native origin of this species. In addition, results suggest that unexpected outbreaks are not a consequence of a single or few pestiferous haplotypes but rather the source of outbreaks are local populations which have experienced an increase in each area. The recent outbreaks have probably appeared independently of the genetic haplotypes whereas environmental conditions could have affected the outbreak populations. These findings contribute to a growing understanding of the status and evolutionary history of the pest that would be useful for developing and implementing biological control strategies for example by maximizing efforts to locate native natural enemies.
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Vandenberghe, Eveline, Berit Boshuizen, Catherine J. G. Delesalle, Lutz S. Goehring, Katy A. Groome, Kees van Maanen, and Cornelis M. de Bruijn. "New Insights into the Management of an EHV-1 (Equine Hospital) Outbreak." Viruses 13, no. 8 (July 22, 2021): 1429. http://dx.doi.org/10.3390/v13081429.
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In May 2018, Wolvega Equine Hospital (WEH) experienced an EHV-1 outbreak. This outbreak caused significant economic losses and negative publicity for the hospital. How should hospitals prepare themselves for these outbreaks and prevent shedding of the virus on multiple neighboring premises? The hospital transformed most of its activities into mobile practice and the entire infected hospital population was moved to a separate remote location. The hospital was cleaned and disinfected according to the latest recommendations before reopening. Four neighboring professional equine businesses and three privately owned premises were affected by the spread of the virus from the hospital population and initiated quarantine restrictions. Equine hospitals should prepare themselves for EHV-1 outbreaks as the intake of the virus cannot be prevented. A management protocol should include public information protocols, swift client information and quarantine measures that ensure quick containment of the outbreak. Timely reopening of the hospital can be achieved by rehousing the contaminated population. It should also include good regulations with clients and a properly carried out release protocol. Equine sports organizations should establish sufficient vaccination coverage in order to decrease the frequency of EHV-1 outbreaks.
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Mahmud, Ayesha S., Md Iqbal Kabir, Kenth Engø-Monsen, Sania Tahmina, Baizid Khoorshid Riaz, Md Akram Hossain, Fahmida Khanom, et al. "Megacities as drivers of national outbreaks: The 2017 chikungunya outbreak in Dhaka, Bangladesh." PLOS Neglected Tropical Diseases 15, no. 2 (February 2, 2021): e0009106. http://dx.doi.org/10.1371/journal.pntd.0009106.
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Background Several large outbreaks of chikungunya have been reported in the Indian Ocean region in the last decade. In 2017, an outbreak occurred in Dhaka, Bangladesh, one of the largest and densest megacities in the world. Population mobility and fluctuations in population density are important drivers of epidemics. Measuring population mobility during outbreaks is challenging but is a particularly important goal in the context of rapidly growing and highly connected cities in low- and middle-income countries, which can act to amplify and spread local epidemics nationally and internationally. Methods We first describe the epidemiology of the 2017 chikungunya outbreak in Dhaka and estimate incidence using a mechanistic model of chikungunya transmission parametrized with epidemiological data from a household survey. We combine the modeled dynamics of chikungunya in Dhaka, with mobility estimates derived from mobile phone data for over 4 million subscribers, to understand the role of population mobility on the spatial spread of chikungunya within and outside Dhaka during the 2017 outbreak. Results We estimate a much higher incidence of chikungunya in Dhaka than suggested by official case counts. Vector abundance, local demographics, and population mobility were associated with spatial heterogeneities in incidence in Dhaka. The peak of the outbreak in Dhaka coincided with the annual Eid holidays, during which large numbers of people traveled from Dhaka to other parts of the country. We show that travel during Eid likely resulted in the spread of the infection to the rest of the country. Conclusions Our results highlight the impact of large-scale population movements, for example during holidays, on the spread of infectious diseases. These dynamics are difficult to capture using traditional approaches, and we compare our results to a standard diffusion model, to highlight the value of real-time data from mobile phones for outbreak analysis, forecasting, and surveillance.
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Guerrero-Vadillo, María, Marina Peñuelas, Ángela Domínguez, Pere Godoy, Diana Gómez-Barroso, Nuria Soldevila, Conchita Izquierdo, et al. "Epidemiological Characteristics and Spatio-Temporal Distribution of Hepatitis A in Spain in the Context of the 2016/2017 European Outbreak." International Journal of Environmental Research and Public Health 19, no. 24 (December 14, 2022): 16775. http://dx.doi.org/10.3390/ijerph192416775.
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The aim of our study was to describe the results of the epidemiological surveillance of hepatitis A infections in Spain in the context of the 2016/2017 European outbreak, particularly of hepatitis A outbreaks reported in the MSM population, incorporating the results of a spatio-temporal analysis of cases. Hepatitis A cases and outbreaks reported in 2016–2017 to the National Epidemiological Surveillance Network were reviewed: outbreaks in which some of the cases belonged to the MSM group were described, and clusters of hepatitis A cases in men and women were analysed using a space–time scan statistic. Twenty-six outbreaks were identified, with a median size of two cases per outbreak, with most of the outbreak-related cases belonging to the 15–44 years-old group. Nearly 85% occurred in a household setting, and in all outbreaks, the mode of transmission was direct person-to-person contact. Regarding space–time analysis, twenty statistically significant clusters were identified in the male population and eight in the female population; clusters in men presented a higher number of observed cases and affected municipalities, as well as a higher percentage of municipalities classified as large urban areas. The elevated number of cases detected in clusters of men indicates that the number of MSM-related outbreaks may be higher than reported, showing that spatio-temporal analysis is a complementary, useful tool which may improve the detection of outbreaks in settings where epidemiological investigation may be more challenging.
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Besney, Jonathan, Danusia Moreau, Angela Jacobs, Dan Woods, Diane Pyne, A. Mark Joffe, and Rabia Ahmed. "Influenza outbreak in a Canadian correctional facility." Journal of Infection Prevention 18, no. 4 (February 17, 2017): 193–98. http://dx.doi.org/10.1177/1757177416689725.
Повний текст джерелаАнотація:
Correctional facilities face increased risk of communicable disease transmission and outbreaks. We describe the progression of an influenza outbreak in a Canadian remand facility and suggest strategies for preventing, identifying and responding to outbreaks in this setting. In total, six inmates had laboratory-confirmed influenza resulting in 144 exposed contacts. Control measures included enhanced isolation precautions, restricting admissions to affected living units, targeted vaccination and antiviral prophylaxis. This report highlights the importance of setting specific outbreak guidelines in addressing population and environmental challenges, as well as implementation of effective infection prevention and control (IPAC) and public health measures when managing influenza and other communicable disease outbreaks.
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Craft, Meggan E., Erik Volz, Craig Packer, and Lauren Ancel Meyers. "Distinguishing epidemic waves from disease spillover in a wildlife population." Proceedings of the Royal Society B: Biological Sciences 276, no. 1663 (February 25, 2009): 1777–85. http://dx.doi.org/10.1098/rspb.2008.1636.
Повний текст джерелаАнотація:
Serengeti lions frequently experience viral outbreaks. In 1994, one-third of Serengeti lions died from canine distemper virus (CDV). Based on the limited epidemiological data available from this period, it has been unclear whether the 1994 outbreak was propagated by lion-to-lion transmission alone or involved multiple introductions from other sympatric carnivore species. More broadly, we do not know whether contacts between lions allow any pathogen with a relatively short infectious period to percolate through the population (i.e. reach epidemic proportions). We built one of the most realistic contact network models for a wildlife population to date, based on detailed behavioural and movement data from a long-term lion study population. The model allowed us to identify previously unrecognized biases in the sparse data from the 1994 outbreak and develop methods for judiciously inferring disease dynamics from typical wildlife samples. Our analysis of the model in light of the 1994 outbreak data strongly suggest that, although lions are sufficiently well connected to sustain epidemics of CDV-like diseases, the 1994 epidemic was fuelled by multiple spillovers from other carnivore species, such as jackals and hyenas.
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Kang, Hansol, Yvette Khachadourian, Dana Perella, Tiina M. Peritz, Kristen A. Feemster, and Susan E. Coffin. "The burden of gastroenteritis outbreaks in long-term care settings in Philadelphia, 2009–2018." Infection Control & Hospital Epidemiology 41, no. 11 (August 17, 2020): 1310–14. http://dx.doi.org/10.1017/ice.2020.263.
Повний текст джерелаАнотація:
AbstractObjective:Gastroenteritis causes significant morbidity and mortality in long-term care facility (LTCF) residents, a growing population within the United States. We set out to better understand gastroenteritis outbreaks in LTCF by identifying outbreak and facility characteristics associated with outbreak incidence as well as outbreak duration and size.Design:We conducted a retrospective cross-sectional study on LTCFs in Philadelphia County from 2009 to 2018. Outbreak characteristics and interventions were extracted from Philadelphia Department of Public Health (PDPH) database and quality data on all LTCFs was extracted from Centers for Medicare and Medicaid Services Nursing Home Compare database.Results:We identified 121 gastroenteritis outbreaks in 49 facilities. Numbers of affected patients ranged from 2 to 211 patients (median patient illness rate, 17%). Staff were reported ill in 94 outbreaks (median staff illness rate, 5%). Outbreak facilities were associated with higher occupancy rates (91% vs 88%; P = .033) and total bed numbers (176 vs 122; P = .071) compared to nonoutbreak facilities. Higher rates of staff illness were associated with prolonged outbreaks (13% vs 4%; P < .001) and higher patient illness rates (9% vs 4%; P = .012). Prolonged outbreaks were associated with lower frequency of cohorting for outbreak management (13% vs 41%; P = .046).Conclusion:This study is the largest published analysis of gastroenteritis outbreaks in LTCFs. Facility characteristics and staff disease activity were associated with more severe outbreaks. Heightened surveillance for gastrointestinal symptoms among staff and increased use of cohorting might reduce the risk of prolonged gastroenteritis outbreaks in LTCF.
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Chen, Yuliang, Tao Liu, Xiaolin Yu, Qinghui Zeng, Zixi Cai, Haisheng Wu, Qingying Zhang, et al. "An ensemble forecast system for tracking dynamics of dengue outbreaks and its validation in China." PLOS Computational Biology 18, no. 6 (June 27, 2022): e1010218. http://dx.doi.org/10.1371/journal.pcbi.1010218.
Повний текст джерелаАнотація:
As a common vector-borne disease, dengue fever remains challenging to predict due to large variations in epidemic size across seasons driven by a number of factors including population susceptibility, mosquito density, meteorological conditions, geographical factors, and human mobility. An ensemble forecast system for dengue fever is first proposed that addresses the difficulty of predicting outbreaks with drastically different scales. The ensemble forecast system based on a susceptible-infected-recovered (SIR) type of compartmental model coupled with a data assimilation method called the ensemble adjusted Kalman filter (EAKF) is constructed to generate real-time forecasts of dengue fever spread dynamics. The model was informed by meteorological and mosquito density information to depict the transmission of dengue virus among human and mosquito populations, and generate predictions. To account for the dramatic variations of outbreak size in different seasons, the effective population size parameter that is sequentially updated to adjust the predicted outbreak scale is introduced into the model. Before optimizing the transmission model, we update the effective population size using the most recent observations and historical records so that the predicted outbreak size is dynamically adjusted. In the retrospective forecast of dengue outbreaks in Guangzhou, China during the 2011–2017 seasons, the proposed forecast model generates accurate projections of peak timing, peak intensity, and total incidence, outperforming a generalized additive model approach. The ensemble forecast system can be operated in real-time and inform control planning to reduce the burden of dengue fever.
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Turnock, W. J. "DENSITY, PARASITISM, AND DISEASE INCIDENCE OF LARVAE OF THE BERTHA ARMYWORM, MAMESTRA CONFIGURATA WALKER (LEPIDOPTERA: NOCTUIDAE), IN MANITOBA, 1973–1986’." Canadian Entomologist 120, no. 5 (May 1988): 401–13. http://dx.doi.org/10.4039/ent120401-5.
Повний текст джерелаАнотація:
AbstractPopulations of larvae of the bertha armyworm, Mamestra configurata Wlk., in four physiographic regions of Manitoba showed similar trends over time: a decline from the outbreak of 1971–1972 to very low densities in 1975–1977, an increase to a peak during the years 1979–1981, and a subsequent decline. During the period of peak larval populations, brief (1 or 2 years) outbreaks [at least some fields with > 20 larvae per square metre) occurred at five locations in two regions, the Swan River Plain and the Valley River Plain, but not in the Western Uplands or the Manitoba Lowlands. In the first two regions, larval densities rose rapidly (from < 1.6 to > 13.8/m2) in 1 year. Although the general trend of population density was similar, there were differences in density among and within regions, and in the timing, severity, and duration of peak populations. Two parasitoids (Banchus flavescens Cress., Athrycia cinerea (Coq.)) and two pathogens (a nuclear polyhedrosis virus (NPV) and fungi of the Entomophthorales) occurred regularly in larval populations. Of these, B. flavescens had the highest constancy among collections and may help to keep bertha armyworm populations at low densities. NPV was rarely found among larvae from low-density populations but appeared in all populations that reached outbreak levels. No single biotic agent could be associated with the population declines because of multiple parasitism and the difficulty in partitioning mortality when only a single sample could be taken. The rapid increase of bertha armyworm larvae from very low to outbreak levels in 1 year will prevent predictions of outbreaks from being based on larval densities in the preceding year.
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BARMAK, D. H., C. O. DORSO, M. OTERO, and H. G. SOLARI. "Modelling interventions during a dengue outbreak." Epidemiology and Infection 142, no. 3 (June 26, 2013): 545–61. http://dx.doi.org/10.1017/s0950268813001301.
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SUMMARYWe present a stochastic dynamical model for the transmission of dengue that considers the co-evolution of the spatial dynamics of the vectors (Aedes aegypti) and hosts (human population), allowing the simulation of control strategies adapted to the actual evolution of an epidemic outbreak. We observed that imposing restrictions on the movement of infected humans is not a highly effective strategy. In contrast, isolating infected individuals with high levels of compliance by the human population is efficient even when implemented with delays during an ongoing outbreak. We also studied insecticide-spraying strategies assuming different (hypothetical) efficiencies. We observed that highly efficient fumigation strategies seem to be effective during an outbreak. Nevertheless, taking into account the controversial results on the use of spraying as a single control strategy, we suggest that carrying out combined strategies of fumigation and isolation during an epidemic outbreak should account for a suitable strategy for the attenuation of epidemic outbreaks.
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Chuffi, Samira, Michele S. Gomes-Gouvêa, Luciana V. B. Casadio, Ana Catharina S. S. Nastri, Mario P. Gonzalez, André L. F. Cotia, Amanda G. D. Aranda, et al. "The Molecular Characterization of Hepatitis A Virus Strains Circulating during Hepatitis A Outbreaks in São Paulo, Brazil, from September 2017 to May 2019." Viruses 14, no. 1 (December 31, 2021): 73. http://dx.doi.org/10.3390/v14010073.
Повний текст джерелаАнотація:
Outbreaks of hepatitis A may occur in countries of medium and high socioeconomic levels in which the population generally exhibits an increased susceptibility in young adults to this infection if they are not vaccinated against the hepatitis A virus (HAV). In Europe, an outbreak involved approximately 22 European countries with 4475 cases reported from 2016 to 2018; most of them were men who have sex with men (MSM). This outbreak expanded to North and South America, including Brazil, particularly in São Paulo city with 1547 reported cases from 2016 to 2019. In the present study, we characterized the HAV strains involved in the acute hepatitis A cases identified in the reference centers of São Paulo city during this outbreak. A total of 51 cases with positive anti-HAV IgM were included, 80.4% male, 68.6% of them between 20 and 40 years old and 41.7% MSM. HAV RNA was detected in 92% (47/51) of the cases. Subgenotype IA of HAV was identified and most of the strains were closely related to that isolated in outbreaks that occurred in different European countries in 2016. These results showed the epidemiological relation between these outbreaks and reinforce the need to implement vaccination against hepatitis A for the adult population, particularly for a population with a high-risk behavior.
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Zhu, W. C., J. T. Sun, J. Dai, J. R. Huang, L. Chen, and X. Y. Hong. "New microsatellites revealed strong gene flow among populations of a new outbreak pest, Athetis lepigone (Möschler)." Bulletin of Entomological Research 108, no. 5 (November 27, 2017): 636–44. http://dx.doi.org/10.1017/s000748531700116x.
Повний текст джерелаАнотація:
AbstractAthetis lepigone (Möschler) (Lepidoptera: Noctuidae) is a new outbreak pest in China. Consequently, it is unclear whether the emergence and spread of the outbreak of this pest are triggered by rapid in situ population size increases in each outbreak area, or by immigrants from a potential source area in China. In order to explore the outbreak process of this pest through a population genetics approach, we developed ten novel polymorphic expressed sequence tags (EST)-derived microsatellites. These new microsatellites had moderately high levels of polymorphism in the tested population. The number of alleles per locus ranged from 3 to 19, with an average of 8.6, and the expected heterozygosity ranged from 0.269 to 0.783. A preliminary population genetic analysis using these new microsatellites revealed a lack of population genetic structure in natural populations of A. lepigone. The estimates of recent migration rate revealed strong gene flow among populations. In conclusion, our study developed the first set of EST-microsatellite markers and shed a new light on the population genetic structure of this pest in China.
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Ishfaq, Romah, S. M. Abbas Naqvi, Mehvish Javeed, Atif Zulfiqar, Hubza Ruatt Khan, and Ahsanullah M. Mirbahar. "Cholera: An Outbreak Causing Diarrhoea; A Serious Threat to Population." Pakistan Journal of Medical and Health Sciences 16, no. 11 (November 30, 2022): 245–47. http://dx.doi.org/10.53350/pjmhs20221611245.
Повний текст джерелаАнотація:
Objective: To evaluate the association of Vibrio cholera infection with age and gender. To develop the antibiotic sensitivity pattern for Vibrio cholera against commercially available preparations in market. Study Design: Descriptive cross-sectional Place and duration: Study was conducted at department of Pathology, Nishtar Medical University and Hospital Multan, in the months from April to September, 2022. Methodology: Total 191 Stool samples were sent to Microbiology laboratory, Pathology department of hospital which was included in this study. These samples were from Nishtar Hospital various wards and from CEO office. After successful isolation of bacteria the antibiotic sensitivity were tested by Kirby-Baur Disc Diffusion Method. Results: During the outbreak of Vibrio cholera in our area, 10.99% cases were detected in whole diseased population. Mean age of patients who developed Vibrio cholera was 7.68 + 0.66 years. Gender showed no discrimination as both males and females were almost equally affected. Age and gender were not found statistically significant (p=0.740 and p=0.329). The sensitivity was measured for three antibiotic drugs (Ampicillin, Erythromycin and Tetracycline). Among them only Ampicillin showed 50% sensitivity whiles other two antibiotics were 100% sensitive. Conclusion: Unhygienic environment especially in pediatrics group has showed to be the main risk factor in the outbreaks of cholera. Proper disposal of waste, especially from infected persons, to keep it segregated from drinking water along with awareness programs are the need of hour to prevent further outbreaks. Keywords: Kirby-Baur Disc Diffusion Method, Vibrio cholera, Outbreak, Pediatrics, Ampicillin, Erythromycin and Tetracycline
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HOANG, L. M. N., M. FYFE, C. ONG, J. HARB, S. CHAMPAGNE, B. DIXON, and J. ISAAC-RENTON. "Outbreak of cyclosporiasis in British Columbia associated with imported Thai basil." Epidemiology and Infection 133, no. 1 (December 9, 2004): 23–27. http://dx.doi.org/10.1017/s0950268804003176.
Повний текст джерелаАнотація:
Sporadic outbreaks of cyclosporiasis, a common cause of protracted diarrhoea in underdeveloped countries, are often undetected and undiagnosed in industrial countries. In May 2001, an outbreak of Cyclospora cayetanensis gastroenteritis was identified in British Columbia, Canada, with 17 reported cases. We conducted a case-control study involving 12 out of the 17 reported and confirmed case patients. Eleven (92%) of the patients had consumed Thai basil, an essential ingredient in Vietnamese cuisine, compared to 3 out of 16 (19%) of the control patients (P=0·003). Trace-back investigations implicated Thai basil imported via the United States as the vehicle for this outbreak. This is the first documented sporadic outbreak of cyclosporiasis linked to Thai basil in Canada, and the first outbreak of cyclosporiasis identified in an ethnic immigrant population. This outbreak provides the opportunity to increase our understanding of this emerging pathogen and improve on our prevention and control for future outbreaks.
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Yagci Sokat, Kezban, and Benjamin Armbruster. "Modeling and Controlling Epidemic Outbreaks: The Role of Population Size, Model Heterogeneity and Fast Response in the Case of Measles." Mathematics 8, no. 11 (October 31, 2020): 1892. http://dx.doi.org/10.3390/math8111892.
Повний текст джерелаАнотація:
Modelers typically use detailed simulation models and vary the fraction vaccinated to study outbreak control. However, there is currently no guidance for modelers on how much detail (i.e., heterogeneity) is necessary and how large a population to simulate. We provide theoretical and numerical guidance for those decisions and also analyze the benefit of a faster public health response through a stochastic simulation model in the case of measles in the United States. Theoretically, we prove that the outbreak size converges as the simulation population increases and that the outbreaks are slightly larger with a heterogeneous community structure. We find that the simulated outbreak size is not sensitive to the size of the simulated population beyond a certain size. We also observe that in case of an outbreak, a faster public health response provides benefits similar to increased vaccination. Insights from this study can inform the control and elimination measures of the ongoing coronavirus disease (COVID-19) as measles has shown to have a similar structure to COVID-19.
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Ehelepola, N. D. B., and W. M. C. M. Wijesinghe. "An Analysis of a Dengue Outbreak at a Large Hospital and Epidemiological Evidence for Nosocomial Dengue." Journal of Tropical Medicine 2018 (June 26, 2018): 1–9. http://dx.doi.org/10.1155/2018/9579086.
Повний текст джерелаАнотація:
Reports on dengue outbreaks at hospitals are extremely rare. Here the authors analyze a dengue outbreak at the Teaching Hospital-Kandy (THK), Sri Lanka. Our hypothesis was that the present outbreak of dengue was due to nosocomial infections. Our objectives were to illustrate epidemiological evidence for nosocomial dengue infections among THK workers and comparison of dengue incidence of hospital workers of wards that treat dengue patients with workers of other wards, to ascertain whether most nosocomial dengue incidences occur closer to where dengue patients are treated and vector larvae were detected, and to draw the attention of the medical community to the significance of hospital outbreaks, making suggestions on how to improve dengue preventive work at the THK. We calculated weekly dengue incidences for the hospital workers and for the surrounding Kandy district population, plotted epicurves, and compared them. We also compared these with the temporal changes of numbers of patients who were admitted for other illnesses and then diagnosed with dengue and the numbers of containers with vector mosquito larvae found on hospital premises. Dengue incidence of the hospital workers for the 24-week study period (2388 per 100000 population) was significantly high when compared to incidence of the district (151 per 100000 population). Peaks of dengue incidence in hospital workers, the numbers of patients hospitalized for other illnesses contracting dengue, and numbers of containers with vector larvae occurred in the same week. The peak dengue incidence of the Kandy district happened six weeks later. There was no evidence to indicate blood contact causing dengue among hospital workers. The outbreak was controlled while dengue was rising in the district. This evidence indicates a probable nosocomial dengue outbreak. This outbreak adversely affected hospital workers, patients, and the community. We propose some measures to prevent such outbreaks.
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Wallner, W. E. "Factors Affecting Insect Population Dynamics: Differences Between Outbreak and Non-Outbreak Species." Annual Review of Entomology 32, no. 1 (January 1987): 317–40. http://dx.doi.org/10.1146/annurev.en.32.010187.001533.
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RINALDI, SERGIO. "SYNCHRONY IN SLOW–FAST METACOMMUNITIES." International Journal of Bifurcation and Chaos 19, no. 07 (July 2009): 2447–53. http://dx.doi.org/10.1142/s0218127409024220.
Повний текст джерелаАнотація:
The synchronization of metacommunities due to dispersal among patches is analyzed in the case of slow–fast populations. The analysis is performed by studying a standard model with the fast population dispersing when special meteorological conditions are present. This assumption fits very well with the peculiar nature of slow–fast systems and implies that metacommunities synchronize if the slow population accelerates during the outbreak of the fast population. This result shows great potential in the study of marine and fresh-water plankton communities as well as in the study of synchronization of insect-pest outbreaks in forests.
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Xiang, Changcheng, Sanyi Tang, Robert A. Cheke, and Wenjie Qin. "A Locust Phase Change Model with Multiple Switching States and Random Perturbation." International Journal of Bifurcation and Chaos 26, no. 13 (December 15, 2016): 1630037. http://dx.doi.org/10.1142/s0218127416300378.
Повний текст джерелаАнотація:
Insects such as locusts and some moths can transform from a solitarious phase when they remain in loose populations and a gregarious phase, when they may swarm. Therefore, the key to effective management of outbreaks of species such as the desert locust Schistocercagregaria is early detection of when they are in the threshold state between the two phases, followed by timely control of their hopper stages before they fledge because the control of flying adult swarms is costly and often ineffective. Definitions of gregarization thresholds should assist preventive control measures and avoid treatment of areas that might not lead to gregarization. In order to better understand the effects of the threshold density which represents the gregarization threshold on the outbreak of a locust population, we developed a model of a discrete switching system. The proposed model allows us to address: (1) How frequently switching occurs from solitarious to gregarious phases and vice versa; (2) When do stable switching transients occur, the existence of which indicate that solutions with larger amplitudes can switch to a stable attractor with a value less than the switching threshold density?; and (3) How does random perturbation influence the switching pattern? Our results show that both subsystems have refuge equilibrium points, outbreak equilibrium points and bistable equilibria. Further, the outbreak equilibrium points and bistable equilibria can coexist for a wide range of parameters and can switch from one to another. This type of switching is sensitive to the intrinsic growth rate and the initial values of the locust population, and may result in locust population outbreaks and phase switching once a small perturbation occurs. Moreover, the simulation results indicate that the switching transient patterns become identical after some generations, suggesting that the evolving process of the perturbation system is not related to the initial value after some fixed number of generations for the same stochastic processes. However, the switching frequency and outbreak patterns can be significantly affected by the intensity of noise and the intrinsic growth rate of the locust population.
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Haynes, Kyle J., Ottar N. Bjørnstad, Andrew J. Allstadt, and Andrew M. Liebhold. "Geographical variation in the spatial synchrony of a forest-defoliating insect: isolation of environmental and spatial drivers." Proceedings of the Royal Society B: Biological Sciences 280, no. 1753 (February 22, 2013): 20122373. http://dx.doi.org/10.1098/rspb.2012.2373.
Повний текст джерелаАнотація:
Despite the pervasiveness of spatial synchrony of population fluctuations in virtually every taxon, it remains difficult to disentangle its underlying mechanisms, such as environmental perturbations and dispersal. We used multiple regression of distance matrices (MRMs) to statistically partition the importance of several factors potentially synchronizing the dynamics of the gypsy moth, an invasive species in North America, exhibiting outbreaks that are partially synchronized over long distances (approx. 900 km). The factors considered in the MRM were synchrony in weather conditions, spatial proximity and forest-type similarity. We found that the most likely driver of outbreak synchrony is synchronous precipitation. Proximity played no apparent role in influencing outbreak synchrony after accounting for precipitation, suggesting dispersal does not drive outbreak synchrony. Because a previous modelling study indicated weather might indirectly synchronize outbreaks through synchronization of oak masting and generalist predators that feed upon acorns, we also examined the influence of weather and proximity on synchrony of acorn production. As we found for outbreak synchrony, synchrony in oak masting increased with synchrony in precipitation, though it also increased with proximity. We conclude that precipitation could synchronize gypsy moth populations directly, as in a Moran effect, or indirectly, through effects on oak masting, generalist predators or diseases.
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Stephens, Patrick R., N. Gottdenker, A. M. Schatz, J. P. Schmidt, and John M. Drake. "Characteristics of the 100 largest modern zoonotic disease outbreaks." Philosophical Transactions of the Royal Society B: Biological Sciences 376, no. 1837 (September 20, 2021): 20200535. http://dx.doi.org/10.1098/rstb.2020.0535.
Повний текст джерелаАнотація:
Zoonotic disease outbreaks are an important threat to human health and numerous drivers have been recognized as contributing to their increasing frequency. Identifying and quantifying relationships between drivers of zoonotic disease outbreaks and outbreak severity is critical to developing targeted zoonotic disease surveillance and outbreak prevention strategies. However, quantitative studies of outbreak drivers on a global scale are lacking. Attributes of countries such as press freedom, surveillance capabilities and latitude also bias global outbreak data. To illustrate these issues, we review the characteristics of the 100 largest outbreaks in a global dataset ( n = 4463 bacterial and viral zoonotic outbreaks), and compare them with 200 randomly chosen background controls. Large outbreaks tended to have more drivers than background outbreaks and were related to large-scale environmental and demographic factors such as changes in vector abundance, human population density, unusual weather conditions and water contamination. Pathogens of large outbreaks were more likely to be viral and vector-borne than background outbreaks. Overall, our case study shows that the characteristics of large zoonotic outbreaks with thousands to millions of cases differ consistently from those of more typical outbreaks. We also discuss the limitations of our work, hoping to pave the way for more comprehensive future studies. This article is part of the theme issue ‘Infectious disease macroecology: parasite diversity and dynamics across the globe’.
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Yousef, Nida, Rashed A. Hasan, and Walid Abuhammour. "Pulmonary Tuberculosis Outbreak in a Pediatric Population." Clinical Pediatrics 52, no. 7 (February 25, 2013): 589–92. http://dx.doi.org/10.1177/0009922813477913.
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Hersh, Bradley S., Paul E. M. Fine, W. Kay Kent, Stephen L. Cochi, Laura H. Kahn, Elizabeth R. Zell, Patrick L. Hays, and Cindy L. Wood. "Mumps outbreak in a highly vaccinated population." Journal of Pediatrics 119, no. 2 (August 1991): 187–93. http://dx.doi.org/10.1016/s0022-3476(05)80726-7.
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Ostapenko, N. A., I. I. Kozlova, M. G. Solovieva, T. F. Stepanova, and V. V. Mefodiev. "EXPERIENCE OF INVESTIGATION OF A LARGE OUTBREAK OF A TULAREMIA AMONG THE POPULATION OF KHANTY-MANSIYSK AND THE KHANTY-MANSIYSK REGION IN 2013." Journal of microbiology epidemiology immunobiology, no. 6 (December 28, 2018): 44–48. http://dx.doi.org/10.36233/0372-9311-2018-6-44-48.
Повний текст джерелаАнотація:
Aim. The experience of investigating a major outbreak of tularemia among the population of Khanty-Mansiysk and Khanty-Mansiysk Region in 2013. Materials and methods. The materials of epidemiological monitoring of activity of foci of tularemia in KhMAO for a long period of time, the results of laboratory studies of biological materials and environmental objects on infection with tularemia pathogen during investigation of the outbreak in 2013 are analyzed. Results. The causes and features of the outbreak development, anti-epidemic and preventive measures were analyzed. An algorithm for investigating tularemia outbreaks has been developed and the effectiveness of preventive and antiepidemic measures for their elimination in a strained natural focus has been shown. Conclusion. Monitoring of natural foci of tularemia confirms the continued preservation of their activity and viability. The transmissive nature of outbreaks causes their scale and intensity, the need for permanent disinsection and deratization measures. The invasion of rodents into populated areas can be considered a predictive sign of the deterioration of the epidemiological situation and the onset of outbreak, which allows taking anti-epidemic measures in advance. Systemic interdepartmental interaction (health care, executive authorities) is needed to strengthen attention to prevention and build up a cautious attitude towards the problem of tularemia.
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Nealis, V. G., and J. Régnière. "Fecundity and recruitment of eggs during outbreaks of the spruce budworm." Canadian Entomologist 136, no. 4 (August 2004): 591–604. http://dx.doi.org/10.4039/n03-089.
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AbstractField data from outbreaks of the spruce budworm, Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae), in Ontario and Quebec show that current-year defoliation is the single greatest determinant of variation in fecundity. The species of tree that served as the foodplant and infections by the microsporidian Nosema fumiferanae (Thomson) (Microsporida) had little effect on mean lifetime fecundity in field populations. During a prolonged outbreak at one location (Black Sturgeon Lake, Ontario), annual lifetime fecundity was inversely related to observed defoliation in the same year, with the highest mean fecundity recorded at the beginning and the end of the outbreak when defoliation was least severe. The overall trend in yearly rate of change in egg density in a population time series at Black Sturgeon Lake was associated more closely with generational survival than with fecundity. Measured fecundity of local moths was greater than estimated per capita rates of recruitment in most years of the outbreak at Black Sturgeon Lake. This suggests that in these years of the outbreak at Black Sturgeon Lake there was a net emigration of egg-carrying moths.
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Chen, Yiqun, Timothy Aldridge, Claire Ferraro, and Fu-Meng Khaw. "COVID-19 outbreak rates and infection attack rates associated with the workplace: a descriptive epidemiological study." BMJ Open 12, no. 7 (July 2022): e055643. http://dx.doi.org/10.1136/bmjopen-2021-055643.
Повний текст джерелаАнотація:
ObjectivesA large number of COVID-19 outbreaks/clusters have been reported in a variety of workplace settings since the start of the pandemic but the rate of outbreak occurrence in the workplace has not previously been assessed. The objectives of this paper are to identify the geographical areas and industrial sectors with a high rate of outbreaks of COVID-19 and to compare infection attack rates by enterprise size and sector in England.MethodsPublic Health England (PHE) HPZone data on COVID-19 outbreaks in workplaces, between 18 May and 12 October 2020, were analysed. The workplace outbreak rates by region and sector were calculated, using National Population Database (NPD) with the total number of workplaces as the denominator. The infection attack rates were calculated by enterprise size and sector using PHE Situations of Interest data with the number of test-confirmed COVID-19 cases in a workplace outbreak as the numerator and using NPD data with the number employed in that workplace as the denominator.ResultsThe highest attack rate was for outbreaks in close contact services (median 16.5%), followed by outbreaks in restaurants and catering (median 10.2%), and in manufacturers and packers of non-food products (median 6.7%). The overall outbreak rate was 66 per 100 000 workplaces. Of the nine English regions, the North West had the highest workplace outbreak rate (155 per 100 000 workplaces). Of the industrial sectors, manufacturers and packers of food had the highest outbreak rate (1672 per 100 000), which was consistent across seven of the regions. In addition, high outbreak rates in warehouses were observed in the East Midlands and the North West.ConclusionsEarly identification of geographical regions and industrial sectors with higher rates of COVID-19 workplace outbreaks can inform interventions to limit transmission of SARS-CoV-2.
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Büntgen, Ulf, Andrew Liebhold, Daniel Nievergelt, Beat Wermelinger, Alain Roques, Frederick Reinig, Paul J. Krusic, et al. "Return of the moth: rethinking the effect of climate on insect outbreaks." Oecologia 192, no. 2 (January 9, 2020): 543–52. http://dx.doi.org/10.1007/s00442-019-04585-9.
Повний текст джерелаАнотація:
AbstractThe sudden interruption of recurring larch budmoth (LBM; Zeiraphera diniana or griseana Gn.) outbreaks across the European Alps after 1982 was surprising, because populations had regularly oscillated every 8–9 years for the past 1200 years or more. Although ecophysiological evidence was limited and underlying processes remained uncertain, climate change has been indicated as a possible driver of this disruption. An unexpected, recent return of LBM population peaks in 2017 and 2018 provides insight into this insect’s climate sensitivity. Here, we combine meteorological and dendrochronological data to explore the influence of temperature variation and atmospheric circulation on cyclic LBM outbreaks since the early 1950s. Anomalous cold European winters, associated with a persistent negative phase of the North Atlantic Oscillation, coincide with four consecutive epidemics between 1953 and 1982, and any of three warming-induced mechanisms could explain the system’s failure thereafter: (1) high egg mortality, (2) asynchrony between egg hatch and foliage growth, and (3) upward shifts of outbreak epicentres. In demonstrating that LBM populations continued to oscillate every 8–9 years at sub-outbreak levels, this study emphasizes the relevance of winter temperatures on trophic interactions between insects and their host trees, as well as the importance of separating natural from anthropogenic climate forcing on population behaviour.
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Maier, Benjamin F., and Dirk Brockmann. "Effective containment explains subexponential growth in recent confirmed COVID-19 cases in China." Science 368, no. 6492 (April 8, 2020): 742–46. http://dx.doi.org/10.1126/science.abb4557.
Повний текст джерелаАнотація:
The recent outbreak of coronavirus disease 2019 (COVID-19) in mainland China was characterized by a distinctive subexponential increase of confirmed cases during the early phase of the epidemic, contrasting with an initial exponential growth expected for an unconstrained outbreak. We show that this effect can be explained as a direct consequence of containment policies that effectively deplete the susceptible population. To this end, we introduce a parsimonious model that captures both quarantine of symptomatic infected individuals, as well as population-wide isolation practices in response to containment policies or behavioral changes, and show that the model captures the observed growth behavior accurately. The insights provided here may aid the careful implementation of containment strategies for ongoing secondary outbreaks of COVID-19 or similar future outbreaks of other emergent infectious diseases.
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JERVIS, RACHEL H., HILLARY BOOTH, ALICIA B. CRONQUIST, JOSHUA ROUNDS, NISHA B. ALDEN, and CRAIG W. HEDBERG. "Moving Away from Population-Based Case-Control Studies during Outbreak Investigations." Journal of Food Protection 82, no. 8 (July 23, 2019): 1412–16. http://dx.doi.org/10.4315/0362-028x.jfp-19-077.
Повний текст джерелаАнотація:
ABSTRACT Population-based case-control studies are a time- and labor-intensive component of foodborne outbreak investigations. One alternative is a binomial trial that asks the question “if the likelihood of each case's having eaten a given food is no different from that of the average person in the population, how often would we find, by chance alone, that x of n (or more) cases would have eaten this food?” Calculating a binomial trial requires background exposure data. We conducted case-control studies and binomial trials in two foodborne outbreaks and compared results. In both outbreaks, using binomial trials we found much less than a 5% probability that the number of cases eating the suspected food vehicle would have occurred by chance. These results were comparable with results of the case-control studies, but with considerably less effort. When background exposure data are available, binomial trials are an efficient way to explore hypotheses that can be further tested by traceback efforts to identify a common source.
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Zacher, Benedikt, and Irina Czogiel. "Supervised learning using routine surveillance data improves outbreak detection of Salmonella and Campylobacter infections in Germany." PLOS ONE 17, no. 5 (May 5, 2022): e0267510. http://dx.doi.org/10.1371/journal.pone.0267510.
Повний текст джерелаАнотація:
The early detection of infectious disease outbreaks is a crucial task to protect population health. To this end, public health surveillance systems have been established to systematically collect and analyse infectious disease data. A variety of statistical tools are available, which detect potential outbreaks as abberations from an expected endemic level using these data. Here, we present supervised hidden Markov models for disease outbreak detection, which use reported outbreaks that are routinely collected in the German infectious disease surveillance system and have not been leveraged so far. This allows to directly integrate labeled outbreak data in a statistical time series model for outbreak detection. We evaluate our model using real Salmonella and Campylobacter data, as well as simulations. The proposed supervised learning approach performs substantially better than unsupervised learning and on par with or better than a state-of-the-art approach, which is applied in multiple European countries including Germany.
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Kraut, Roni Y., Kate G. Snedeker, Oksana Babenko, and Lance Honish. "Influence of School Year on Seasonality of Norovirus Outbreaks in Developed Countries." Canadian Journal of Infectious Diseases and Medical Microbiology 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/9258140.
Повний текст джерелаАнотація:
Factors affecting the seasonal distribution of norovirus outbreaks are not well understood. This study examined whether grade school settings at the start of the school year may be a factor. We searched Ovid Medline from January 2002 to June 2014 for studies that provided all reported norovirus outbreaks in a developed country by month for a minimum of three years. Historical school years were obtained from verifiable sources. The start of the norovirus seasonal outbreak peak and peak outbreak month were determined for each study and compared to the start month of school. Northern hemisphere and southern hemisphere countries had a different norovirus seasonality and different school year structures (traditional compared to year round). In the two studies that provided outbreaks by age, outbreaks among children started several months before outbreaks in the adult population. The median number of months between school start and start of the seasonal outbreak peak was two months (interquartile range [IQR] = 2.0–3.0), while the median number of months between school start and peak outbreak month was four months (IQR = 3.0–4.0). These findings suggest the possibility the school setting at the start of the school year may be a factor in the seasonality of norovirus.
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Perera, P. A. C. R., M. P. Hassell, and H. C. J. Godfray. "Population dynamics of the coconut caterpillar, Opisina arenosella Walker (Lepidoptera: Xyloryctidae), in Sri Lanka." Bulletin of Entomological Research 78, no. 3 (September 1988): 479–92. http://dx.doi.org/10.1017/s0007485300013237.
Повний текст джерелаАнотація:
AbstractOpisina arenosella Walker is a defoliating pest of coconut in Sri Lanka. A first attempt was made to understand its population dynamics. Analysis of records of population outbreaks throughout the country from 1965 to 1985 revealed cycles in the population of approximately one generation period, giving the population the appearance of partially discrete generations. There was also evidence for longer cycles of six-month period. Outbreaks occurred throughout the coconut-growing regions of Sri Lanka, and the numbers of outbreaks per year in different provinces were sometimes correlated, indicating a common, probably climatic, triggering mechanism. Parasitism remained high throughout the outbreaks and there was some evidence that pupal parasitism increased towards the end of an outbreak. A working hypothesis that explains the population dynamics of O. arenosella and the origin of outbreaks is presented.