Frequency Of Disease Outbreaks Research Articles

Resource asynchrony and landscape homogenization as drivers of virulence evolution: The case of a directly transmitted disease in a social host.

Throughout the last decades, the emergence of zoonotic diseases and the frequency of disease outbreaks have increased substantially, fuelled by habitat encroachment and vectors overlapping with more hosts due to global change. The virulence of pathogens is one key trait for successful invasion. In order to understand how global change drivers such as habitat homogenization and climate change drive pathogen virulence evolution, we adapted an established individual-based model of host-pathogen dynamics. Our model simulates a population of social hosts affected by a directly transmitted evolving pathogen in a dynamic landscape. Pathogen virulence evolution results in multiple strains in the model that differ in their transmission capability and lethality. We represent the effects of global change by simulating environmental changes both in time (resource asynchrony) and space (homogenization). We found an increase in pathogenic virulence and a shift in strain dominance with increasing landscape homogenization. Our model further indicated that lower virulence is dominant in fragmented landscapes, although pulses of highly virulent strains emerged under resource asynchrony. While all landscape scenarios favoured co-occurrence of low- and high-virulent strains, the high-virulence strains capitalized on the possibility for transmission when host density increased and were likely to become dominant. With asynchrony likely to occur more often due to global change, our model showed that a subsequent evolution towards lower virulence could lead to some diseases becoming endemic in their host populations.

Mental Health: Pandemics, Epidemics and Tau Protein.

It is well established that a wide range of psychological disorders are influenced by the way people live, with lifestyle-related factors playing a substantial role. During the past decade, the effects of major disasters on mental health have drawn a lot of attention. In this review, we compare clinical studies reporting a link between COVID-19 and other pandemics and mental health. Importantly, we also shed light on Tau protein and neurotransmitters as neurobiological factors that might explain this link. A thorough PubMed search was done to gather and summarize published data on the COVID-19 pandemic's effect on mental health. Additionally, these studies were compared to previous research published on PubMed, triggering other pandemic and epidemic impacts on mental health. The COVID-19 epidemic has had the biggest impact on raising awareness about mental health. Moreover, the past century has seen an increase in the frequency of disease outbreaks like MERS-CoV, Ebola, and Influenza, which all had an impact on mental health. However, the exact role of these epidemics on mental health and brain functions is poorly understood. Future research on the underlying pathways may yield essential information for the treatment and prevention of prospective mental diseases in light of the ongoing decline in mental health during the past 10 years.

꿀벌 전염병과 치료 기술 개발 경향

The problem of abnormal temperature on the earth is no longer a problem limited to one place, and it can be said that very few places have the same climate as 100 years ago. Our country is no exception, and the climate change over the past 10 years is very large. Due to climate change and increased exchanges between countries, especially with China, it is expected that there will be changes in the frequency of disease outbreaks and the appearance of strains due to external inflows as well as the existing infectious diseases of honey bee (Apis mellifera and A. cerana). Major advanced countries such as the United States are also conducting research and support for animal-infected diseases related with climate change and increased exchanges to prepare for the occurrence of new infectious diseases, and changes in the cause of infectious diseases. This report intends to investigate the relationship between these trends and the rapid decrease in the number of bees due to climate change and unclear causes to infectious diseases, and to suggest scientific and technological countermeasures.

Investigation of Molecular Pathogen Screening Assays for Use in Delta Smelt

Pathogen surveillance must be part of any population supplementation or reintroduction program for the conservation of threatened and endangered species. The unintended transmission of pathogens can have devastating effects on these already at-risk populations or the natural ecosystem at large. In the San Francisco Estuary (estuary), abundance of the endemic Delta Smelt (Hypomesus transpacificus) has declined to the point where regulatory managers are preparing to augment the wild population using fish propagated in a hatchery to prevent species extinction. Although disease is not an overt cause of population decline, comprehensive pathogen presence and prevalence data are lacking. Here, we performed a pilot study that applied molecular assays originally developed in salmonids to assess the presence of a wide variety of pathogens in the gill tissue of cultured and wild Delta Smelt—as well as cultured fish—deployed in enclosures in the estuary. We found the assays to be highly sensitive, and observed positive detections of a single pathogen, Ichthyophthirius multifiliis, in 13% of cultured Delta Smelt. We also detected ten other pathogens at very low levels in cultured, enclosure-deployed, and wild Delta Smelt that likely represent the ambient pathogen composition in the estuary (as opposed to actual infection). Our results corroborate previous work that cultured Delta Smelt do not appear to present a high risk for pathogen transmission during population supplementation or reintroduction. However, the molecular pathogen screening assays tested here have great utility as an early warning system indicator of when further diagnostic testing might be necessary to limit the extent and frequency of disease outbreaks; their utility will be further increased once they are customized for Delta Smelt.

Investigation of Molecular Pathogen Screening Assays for Use in Delta Smelt

Pathogen surveillance must be part of any population supplementation or reintroduction program for the conservation of threatened and endangered species. The unintended transmission of pathogens can have devastating effects on these already at-risk populations or the natural ecosystem at large. In the San Francisco Estuary (estuary), abundance of the endemic Delta Smelt (Hypomesus transpacificus) has declined to the point where regulatory managers are preparing to augment the wild population using fish propagated in a hatchery to prevent species extinction. Although disease is not an overt cause of population decline, comprehensive pathogen presence and prevalence data are lacking. Here, we performed a pilot study that applied molecular assays originally developed in salmonids to assess the presence of a wide variety of pathogens in the gill tissue of cultured and wild Delta Smelt—as well as cultured fish—deployed in enclosures in the estuary. We found the assays to be highly sensitive, and observed positive detections of a single pathogen, Ichthyophthirius multifiliis, in 13% of cultured Delta Smelt. We also detected ten other pathogens at very low levels in cultured, enclosure-deployed, and wild Delta Smelt that likely represent the ambient pathogen composition in the estuary (as opposed to actual infection). Our results corroborate previous work that cultured Delta Smelt do not appear to present a high risk for pathogen transmission during population supplementation or reintroduction. However, the molecular pathogen screening assays tested here have great utility as an early warning system indicator of when further diagnostic testing might be necessary to limit the extent and frequency of disease outbreaks; their utility will be further increased once they are customized for Delta Smelt.

Involving stakeholders to support sustainable development of the marine lobster aquaculture sector in Vietnam

This paper used a combination of the strengths, weaknesses, opportunities and threats analysis and analytical hierarchy process to analyze the challenges and prospects for the sustainable development of marine lobster aquaculture in Vietnam. This analysis was based on the participation of four stakeholder groups including representatives at the provincial level, district level, and commune level and lobster farmers. The results show that stakeholders have a relatively positive perception about the sustainable development of marine lobster aquaculture in Vietnam because they believe the strengths and opportunities outweigh the weaknesses and threats. The suitable natural conditions in Vietnam were considered as the most important strength, while the many untapped markets and the support of the government for the sector are key opportunities for further developing marine lobster aquaculture. The increased lobster mortality and frequency of disease outbreaks were considered as the main weaknesses. In addition, the complex development of disease pressure and the reliance on the Chinese market were considered the most crucial threats. The findings of this study can be used by policymakers in Vietnam to further develop the marine lobster aquaculture sector.

Quantification of Site Layout and Filter Characteristics on Primary Filter Airflow Reduction on Commercial Swine Sites in Iowa

Fresh air intake filtration is used on commercial swine breeding-gestation-farrowing farms to reduce the frequency of airborne infectious agents. For swine producers, porcine reproductive and respiratory syndrome virus (PRRSV), influenza A virus and Mycoplasma hyopneumoniae are considered the most economically challenging airborne pathogens. Reduced frequency of disease outbreaks has been attributed to retrofitting existing systems with filtration. Economic analysis of operating costs includes energy use, maintenance and replacement of filters. Filter replacement, the largest operational cost, is dependent on filter lifespan. However, limited data is available on filter lifespan and the rate of airflow reduction during the high dust-loading periods typically encountered for filtered swine building ventilation systems. Therefore, the objectives of this study were (1) estimate the average primary filter airflow reduction per day, (2) identify the impact of factors related to site layout, filter characteristics and weather on airflow reduction rates of filters in positive-pressure ventilated buildings and (3) determine methods for reducing average primary filter airflow reduction rate per day during row-crop harvest season. Both filter brand and the installed orientation of the filter significantly (p = 0.0314, p = 0.0419, respectively) impacted airflow reduction rates. All site layout factors were significant (driveway side, p = 0.001; dormer orientation, p = 0.0001; and dormer configuration, p = 0.0001). The materials tested significantly reduced the airflow reduction rate during row-crop harvest. The information obtained in this study will aid producers when planning for filtration, highlight details relevant to the purchase and installation of filters, identify factors that affect filter lifespan and identify methods for improving filter lifespan.

Village health team functionality and adherence to reporting requirements for community-based surveillance in Kasese, Uganda, 2016

Introduction: Uganda and particularly Kasese District has a high number and frequency of disease outbreaks whose detection and reporting at community level is usually absent or delayed. Most outbreaks in Kasese are detected at health facility level although the earliest point of detection should be at community level, an indicator of a poorly functioning community surveillance system. According to the Community Based Disease/Event Surveillance system in Uganda, Community Health Workers (CHWs) commonly referred to as Village Health Team members (VHTs) are expected to play a key role in Community Based Surveillance so as to enable early detection and response to priority diseases/events at community level to the nearest health facility. This study aimed to assess CHW functionality and adherence to Community Based Disease/Event Surveillance (CBS) guidelines as well as factors associated with it in Kasese so as to identify ways of enabling CHWs to improve CBS.

Organik Asitler ve Su Ürünleri Yetiştiriciliğinde Kullanımı

Organik asitlerin su ürünleri yetiştiriciliğinde, fonksiyonel yem katkı maddeleri olarak kullanılmasının öngörülebilir gelecekte belirgin bir şekilde artacağı düşünülmektedir. Dünya su ürünleri yetiştiriciliğinin sürekli genişlemesi, büyük bir pazar potansiyeli oluşturmaktadır. Bununla birlikte küresel ısınmanın bir sonucu olarak, su ürünleri yetiştiriciliğinde hastalık salgınlarında artma tehlikesi, önemli bir problem olarak ortaya çıkabilecektir. Birçok ülkede antibiyotik kullanımına ilişkin yasaklar veya kısıtlama uygulamaları bulunmaktadır. Su ürünleri yetiştiriciliğinde, antibiyotiklere karşı uygulanabilir bir alternatif olarak organik asitlerin kullanımının uygunluğunu, yapılan çalışmalar ile ortaya konulmaktadır. Organik asitler, antimikrobiyal özelliklerinden dolayı zararlı bakterilerin çoğalmasını engelleyerek, hayvanların gastrointestinal sisteminde yararlı bakterilerin büyümesini teşvik ederek, hayvanların sağlığını iyileştirme özelliklerini göstermektedirler. Yapılan çalışmalar, organik asitlerin fonksiyonel yem katkı maddeleri olarak, su ürünleri yetiştiriciliği endüstrisinde sürdürülebilir bir sağlık yönetimi programının bir parçası olarak kullanılabilirliğini ortaya koymaktadır.

Selection on resilience improves disease resistance and tolerance to infections1

Response to infection in animals has 2 main mechanisms: resistance (ability to control pathogen burden) and tolerance (ability to maintain performance given the pathogen burden). Selection on disease resistance and tolerance to infections seems a promising avenue to increase productivity of animals in the presence of disease infections, but it is hampered by a lack of records of pathogen burden of infected animals. Selection on resilience (ability to maintain performance regardless of pathogen burden) may, therefore, be an alternative pragmatic approach, because it does not need records of pathogen burden. Therefore, the aim of this study was to assess response to selection in resistance and tolerance when selecting on resilience compared with direct selection on resistance and tolerance. Monte Carlo simulation was used combined with selection index theory to predict responses to selection. Using EBV for resilience in the absence of records for pathogen burden resulted in favorable responses in resistance and tolerance to infections, with higher responses in tolerance than in resistance. If resistance and tolerance were unfavorably correlated, lower selection responses were obtained, especially in resistance. When the genetic correlation was very unfavorable, the selection response in tolerance became negative. Results showed that lower selection responses in resistance and tolerance were obtained when the frequency of disease outbreaks was 10% rather than 50% of the contemporary groups. The efficiency of selection on EBV for resilience compared with selection on EBV for resistance and tolerance was, however, not affected by the frequency of disease outbreaks. When records on pathogen burden were available, selection responses in resistance, tolerance, and the total breeding goal were 3 to 28%, 66 to 398%, and 2 to 11% higher, respectively, than when using the EBV for resilience, showing a clear benefit of recording pathogen burden. This study shows that selection on resilience is a pragmatic way of increasing disease resistance and tolerance to infections in the absence of records on pathogen burden, but recording pathogen burden would yield higher selection responses in resistance and tolerance.

Genomic evidence of adaptive evolution in emergent Vibrio parahaemolyticus ecotypes

Abstract The ubiquitous marine bacterium Vibrio parahaemolyticus is a leading cause of illness associated with seafood consumption. The emergence of two genetically distinct ecotypes (ST3 and ST36) has led to an alarming increase in the size and frequency of disease outbreaks. We conducted a genomic comparison of 30 V. parahaemolyticus genomes that represent a diverse collection of 15 genetically distinct ecotypes, including newly sequenced representatives of ST3 and ST36, isolated from both clinical and environmental sources. A multistep evolutionary analysis showed that genes associated with sensing and responding to environmental stimuli have evolved under positive selection, identifying examples of convergent evolution between ST3 and ST36. A comparison of predicted proteomes indicated that ST3 and ST36 ecotypes laterally acquired tens of novel genes associated with a variety of functions including dormancy, homeostasis and membrane transport. Genes identified in this study play an apparent role in environmental fitness and may confer cross protection against stressors encountered in the human host. Together, these results show the evolution of stress response is an important genetic mechanism correlated with the recent emergence of the ST3 and ST36 ecotypes.

Why does size matter for viruses – A new paradigm on viral size

Size and shape are the two immutable laws that govern all life forms including viruses. In this study we postulate and evaluate the hypothesis that there exists a strong association between viral geometry and features of viral disease outbreaks. Data on viral disease outbreaks were retrieved from WHO and CDC public domains for a period of twelve years to assess the relationship between viral size and epidemiological factors such as number of outbreaks, case fatality rate, proportion of emerging infectious diseases and transmission routes. We observed a significant correlation between viral size and frequency of disease outbreaks (rho=-0.82, p=0.004), case fatality rate (rho=0.48, p=0.03) and genome size (r=0.79, p<0.001). Viral sizes were significantly different among diverse transmission routes (p<0.001). The proportion of emerging infectious diseases were significantly different between viruses with size <10(5) and >or=10(5)nm(3) (21% vs 64%, p=0.046). In conclusion, this preliminary evidence shows that viral size plays a substantial role in the epidemiology of viral diseases. Our data suggests that small size viruses are associated with more number of outbreaks than large size viruses. Large size viruses are associated with high case fatality rate and can be potential emerging pathogens. Viral size may be crucial for niche selection and specified transmission routes in the susceptible host. Hence, viral geometry should not be neglected in epidemiology and modeling of viral diseases, and planning vaccine strategies.

West Nile Virus Revisited: Consequences for North American Ecology

It has been nine years since West Nile virus (WNV) emerged in New York, and its initial impacts on avian hosts and humans are evident across North America. The direct effects of WNV on avian hosts include documented population declines, but other, indirect ecological consequences of these changed bird communities, such as changes in seed dispersal, insect abundances, and scavenging services, are probable and demand attention. Furthermore, climate (seasonal precipitation and temperature) and land use are likely to influence the intensity and frequency of disease outbreaks, and research is needed to improve mechanistic understanding of these interacting forces. This article reviews the growing body of research describing the ecology of WNV and highlights critical knowledge gaps that must be addressed if we hope to manage disease risk, implement conservation strategies, and make forecasts in the presence of both climate change and WNV—or the next emergent pathogen.

Incidence of peste des petits ruminants (PPR) virus in sheep and goat as detected by immuno-capture ELISA (Ic ELISA)

Peste des petits ruminants (PPR) is a highly contagious disease of domestic and wild small ruminants. Rapid, sensitive and specific laboratory assay is useful to enable timely implementation of appropriate control to restrict the spread of disease. The present study reports observations from 50 laboratory confirmed outbreaks of PPR and provides details of the presence or otherwise of PPR virus (PPRV) in 427 tissue/organ samples from small ruminants. Most of the samples used for the detection of PPR viral antigen were derived from all major regions within the country; however, these samples may not be a true representation of the target population still it provided a lot more information. Monoclonal antibody-based diagnostic kit manufactured by Biological Diagnostic Supplies Ltd., Flow Laboratories and Institute for Animal Health Pirbright, Surrey, England, were used for the detection of PPR viral antigen (immuno-capture ELISA). Findings suggested that the disease outbreaks were more severe in goats than sheep and the frequency of disease outbreaks was greater between the months of January to April as compared to other periods of the year and it was maximum in month of March (almost 33%). Based on the data of 50 outbreaks (427 samples), the prevalence of PPR in small ruminants in Pakistan was 40.98%. A greater number of positive cases were observed in the southern and northern parts of the country (30–60%) as compared to west and south-west (10–30%). These findings may be correlated with variations in the sheep and goat husbandry practices within different geographic regions and the topography of different areas. The study indicated the scenario of virus circulation in the population and prevalence in actual outbreaks situation, which may be kept in mind while deciding the vaccination strategy for the control of disease.

Prevalence and distribution of peste des petits ruminants virus infection in small ruminants in India

Peste des petits ruminants (PPR) is an acute febrile viral disease of goats and sheep characterised by mucopurulent nasal and ocular discharges, necrotising and erosive stomatitis, enteritis and pneumonia. The disease is endemic in India and causes large economic losses each year due to the high rates of mortality and morbidity in infected sheep and goats. The present study reports observations from 58 laboratory confirmed outbreaks of PPR and provides details of the prevalence of antibodies to PPR virus (PPRV) in 4,407 serum samples of small ruminants. Most of the clinical specimens used for the study originated from the northern and central parts of India. Serum samples used for the detection of antibodies to PPRV were derived from a greater number of regions within the country, however, these samples may not be a true representation of the target population (unvaccinated sheep and goats over 3 months old). Indigenously developed monoclonal antibody-based diagnostic kits were used for the detection of PPRV antigen (sandwich enzyme-linked immunosorbent assay [ELISA]) and antibody (competitive ELISA). Findings suggested that the disease outbreaks were more severe in goats than sheep and that the frequency of disease outbreaks was greater between the months of March and June (51.7%) as compared to other periods of the year. Based on the screening of the 4,407 sera samples, the antibody prevalence of PPRV in small ruminants in India was 33% (95% confidence interval: 32.3% to 33.7%). The prevalence of antibodies to PPRV was noted to differ between species (i.e. sheep versus goats), age groups and geographical regions. A greater proportion of the sheep (36.3%) versus the goat (32.4%) population was infected with PPRV. The distribution and prevalence of antibodies to PPRV among various age groups of animals indicated that goats were exposed at an earlier age than the sheep, suggesting that goats may be more susceptible to infection with PPRV. A greater number of positive cases were observed in the southern and southwestern part of the country (30%-60%) as compared to northern India (10%-30%). These findings may be correlated with variations in the sheep and goat husbandry practices within different geographic regions, the topography of different states and the socio-economic status of individual Indian farmers.

Import risk analysis: the experience of Italy.

The authors propose a contribution to the possible revision of Chapters 1.4.1. and 1.4.2. of the International Animal Health Code (Code) of the Office International des Epizooties (OIE). In particular, data are presented to illustrate some of the inadequacies of both the rationale and the results of the method for risk assessment reported in the Code. The method suggested by the Code for risk assessment is based on the calculation of the 'probability of the occurrence of at least one outbreak' of a given disease following the importation of a given quantity of either live animals or animal products (unrestricted risk estimate). This is usually undertaken when dealing with rare events. For a country such as Italy, this method may not be particularly useful as the frequency of disease outbreaks is what should be estimated, so as to provide decision makers with appropriate and relevant information. Practical use of risk information generated by the use of the OIE risk assessment method for swine vesicular disease (SVD) would have encouraged the Chief Veterinary Officer of Italy to prohibit all imports of swine from the Netherlands and Belgium for at least two years in the early 1990s, with the consequential heavy economic losses for both Italy and the exporting countries. On the contrary, the number of actual outbreaks of the disease due to direct imports of swine from Member States of the European Union (EU), which occurred in Italy in 1992, 1993 and 1994 was very low (two to five outbreaks due to direct imports of swine from the Netherlands and one to two from Belgium). An example of a method for assessing the risks associated with high volumes of trade in commodities is also described. This method is based on the Monte Carlo simulation and provides the information required to evaluate the costs of the strategies compared. The method can be used to predict the number of outbreaks which are likely to occur following importation and enables a comparison to be made of alternative safeguards. This would lead to the selection of the most cost-effective one. The comparison is conducted using risk curves and allows a quantitative evaluation and comparison to be made of various scenarios, varying from an absence of safeguards to combinations of various safeguards.