Distinctive egg-laying patterns in terminal versus non-terminal periods in three fruit fly species.

The specific objective of this study was to use a logistic regression model for determining the degree to which egg laying patterns of individual females at the end of life (i.e., terminal segments) in each of three different fruit fly species could be distinguished from the egg-laying patterns over a similar period in midlife (i.

The failure of success: cyclic recurrences of a globally invasive pest.

In the six decades since 1960, the oriental fruit fly, Bactrocera dorsalis (Hendel), has been announced successfully eradicated in California by the U.S. Department of Agriculture a total of 564 times.

An economic analysis of a contingency model utilising vaccination for the control of equine influenza in a non-endemic country.

Background: Equine influenza (EI) is an infectious respiratory disease of horses that has never been reported in New Zealand (NZ). However, the 2007 EI outbreak in Australia, previously EI free, spurred the NZ government and stakeholders into evaluating alternative EI control strategies in order to economically justify any future decision to eradicate or manage EI. To build on the policy debate, this paper presents an epinomic (epidemiologic and economic) modelling approach to evaluate alternative control strategies.

Financial Impact of Foot-and-mouth disease outbreaks on pig farms in the Republic of Korea, 2014/2015.

The financial impact of foot-and-mouth disease (FMD) that occurred in 180 piggeries (100 farrow-to-finish and 80 fattening farms) confirmed infected during the 2014/2015 epidemic in the Republic of Korea was estimated at the farm level. The median loss due to slaughtering of pigs prior to their expected market weights was US$ 71.8 (uncovered compensation-compensation loss) plus US$ 57.

Evaluating the efficacy of regionalisation in limiting high-risk livestock trade movements.

Many countries implement regionalisation as a measure to control economically important livestock diseases. Given that regionalisation highlights the difference in disease risk between animal subpopulations, this may discourage herd managers in low-risk areas from purchasing animals from high-risk areas to protect the disease-free status of their herds. Using bovine tuberculosis (bTB) in New Zealand as a case example, we develop a novel network simulation model to predict how much the frequency of cattle movements between different disease control areas (DCAs) could theoretically change if herd managers adopted the safest practices (preferentially purchasing cattle from areas with the lowest risk of bTB), if herd managers adopted the riskiest practices (preferentially purchasing cattle from areas with the greatest risk of bTB), or if herd managers made trade decisions completely at random (purchasing cattle without consideration for bTB disease risk).

Coastal development and precipitation drive pathogen flow from land to sea: evidence from a Toxoplasma gondii and felid host system.

Rapidly developing coastal regions face consequences of land use and climate change including flooding and increased sediment, nutrient, and chemical runoff, but these forces may also enhance pathogen runoff, which threatens human, animal, and ecosystem health. Using the zoonotic parasite Toxoplasma gondii in California, USA as a model for coastal pathogen pollution, we examine the spatial distribution of parasite runoff and the impacts of precipitation and development on projected pathogen delivery to the ocean. Oocysts, the extremely hardy free-living environmental stage of T.

Decision-making for foot-and-mouth disease control: Objectives matter.

Formal decision-analytic methods can be used to frame disease control problems, the first step of which is to define a clear and specific objective. We demonstrate the imperative of framing clearly-defined management objectives in finding optimal control actions for control of disease outbreaks. We illustrate an analysis that can be applied rapidly at the start of an outbreak when there are multiple stakeholders involved with potentially multiple objectives, and when there are also multiple disease models upon which to compare control actions.

Using molecular epidemiology to track Toxoplasma gondii from terrestrial carnivores to marine hosts: implications for public health and conservation.

Background: Environmental transmission of the zoonotic parasite Toxoplasma gondii, which is shed only by felids, poses risks to human and animal health in temperate and tropical ecosystems. Atypical T. gondii genotypes have been linked to severe disease in people and the threatened population of California sea otters.

A spatial risk assessment of bighorn sheep extirpation by grazing domestic sheep on public lands.

Bighorn sheep currently occupy just 30% of their historic distribution, and persist in populations less than 5% as abundant overall as their early 19th century counterparts. Present-day recovery of bighorn sheep populations is in large part limited by periodic outbreaks of respiratory disease, which can be transmitted to bighorn sheep via contact with domestic sheep grazing in their vicinity. In order to assess the viability of bighorn sheep populations on the Payette National Forest (PNF) under several alternative proposals for domestic sheep grazing, we developed a series of interlinked models.

Evaluation of the benefit of emergency vaccination in a foot-and-mouth disease free country with low livestock density.

Foot-and-mouth disease (FMD) is highly contagious and one of the most economically devastating diseases of cloven-hoofed animals. Scientific-based preparedness about how to best control the disease in a previously FMD-free country is therefore essential for veterinary services. The present study used a spatial, stochastic epidemic simulation model to compare the effectiveness of emergency vaccination with conventional (non-vaccination) control measures in Switzerland, a low-livestock density country.

Toxoplasma gondii, source to sea: higher contribution of domestic felids to terrestrial parasite loading despite lower infection prevalence.

Environmental transmission of Toxoplasma gondii, a global zoonotic parasite, adversely impacts human and animal health. Toxoplasma is a significant cause of mortality in threatened Southern sea otters, which serve as sentinels for disease threats to people and animals in coastal environments. As wild and domestic felids are the only recognized hosts capable of shedding Toxoplasma oocysts into the environment, otter infection suggests land-to-sea pathogen transmission.

Spatial and temporal patterns of Leptospira infection in dogs from northern California: 67 cases (2001-2010).

Objective: To conduct an epidemiological analysis of the spatial and temporal distribution of canine leptospirosis cases in northern California and detect spatial clustering in any region.

Design: Retrospective case-control study.

Animals: 67 dogs with leptospirosis and 271 control dogs.

Assessing alternative low pathogenic avian influenza virus surveillance strategies in a live bird market.

Surveillance, comprised of sampling and testing, of low pathogenic avian influenza virus (LPAIV) in a live bird market (LBM) may enable the detection of the virus, reducing its spread within the market to humans and birds and to other markets within the LBM system. In addition, detection of infected birds would also reduce the probability of reassortment and possible change from a LPAIV to a highly pathogenic avian influenza virus, which would have a devastating impact on the economy, trade, and society. In this paper we present results from a computer simulation model based on previously collected survey and experimental transmission data.

Stochastic modelling of intra-household transmission of hepatitis C virus: evidence for substantial non-sexual infection.

Objective: To simulate the probability of HCV transmission from an HCV seropositive index patient to susceptible household contacts through non-sexual exposures.

Methods: A modified Reed-Frost stochastic simulation model was used to assess the probability of HCV transmission from an HCV seropositive index patient to susceptible household contacts through non-sexual exposures. This mathematical model does not require the specification of infection onset times for individual, nor is it necessary to identify the chains of household infections.

Comparison of enzootic risk measures for predicting West Nile disease, Los Angeles, California, USA, 2004-2010.

In Los Angeles, California, USA, 2 epidemics of West Nile virus (WNV) disease have occurred since WNV was recognized in 2003. To assess which measure of risk was most predictive of human cases, we compared 3 measures: the California Mosquito-Borne Virus Surveillance and Response Plan Assessment, the vector index, and the Dynamic Continuous-Area Space-Time system. A case-crossover study was performed by using symptom onset dates from 384 persons with WNV infection to determine their relative environmental exposure to high-risk conditions as measured by each method.

Spatio-temporal epidemiology of highly pathogenic avian influenza (H5N1) outbreaks in Nigeria, 2006-2008.

From 2006 to 2008, outbreaks of highly pathogenic avian influenza A (HPAI) virus of the H5N1 subtype occurred among poultry in Nigeria. We described the spatio-temporal patterns of the HPAI H5N1 outbreaks in Nigeria. Data of suspected and laboratory confirmed outbreaks maintained at the National Veterinary Research Institute Vom was analyzed using descriptive and exploratory analyses, GIS mapping, global and local spatial statistical analyses using the Cuzick-Edwards' (C-E) test and SaTScan Space-Time Scan Statistic.

Prevalence of low pathogenicity avian influenza virus during 2005 in two U.S. live bird market systems.

Oropharyngeal and cloacal swabs were collected from poultry sold in two live bird market (LBM) systems to estimate the prevalence of low pathogenicity avian influenza virus (LPAIV) shedding during the summer and fall of 2005. Random sampling was conducted in three LBMs in Minnesota where 50 birds were sampled twice weekly for 4 wk, and in three LBMs in a California marketing system. A stratified systematic sampling method was used to collect samples from Southern California LBMs, where LPAIV was detected during routine surveillance.

Emergence and genetic variation of neuraminidase stalk deletions in avian influenza viruses.

When avian influenza viruses (AIVs) are transmitted from their reservoir hosts (wild waterfowl and shorebirds) to domestic bird species, they undergo genetic changes that have been linked to higher virulence and broader host range. Common genetic AIV modifications in viral proteins of poultry isolates are deletions in the stalk region of the neuraminidase (NA) and additions of glycosylation sites on the hemagglutinin (HA). Even though these NA deletion mutations occur in several AIV subtypes, they have not been analyzed comprehensively.

Epidemic and economic impacts of delayed detection of foot-and-mouth disease: a case study of a simulated outbreak in California.

The epidemic and economic impacts of Foot-and-mouth disease virus (FMDV) spread and control were examined by using epidemic simulation and economic (epinomic) optimization models. The simulated index herd was a ≥2,000 cow dairy located in California. Simulated disease spread was limited to California; however, economic impact was assessed throughout the United States and included international trade effects.

Impact of bovine brucellosis eradication programs in the Republic of Korea.

This study concerns a quantitative analysis of the bovine brucellosis eradication program in the Republic of Korea to provide insight into how to plan better future control strategies. In 2004, an active bovine brucellosis eradication program, based principally on intensive test-and-slaughter, was implemented in Korea. With more intensive testing on cattle, the reported incidence rate at herd level increased significantly, becoming 61 times higher in 2006 (225.

Geographic distribution of autism in California: a retrospective birth cohort analysis.

Prenatal environmental exposures are among the risk factors being explored for associations with autism. We applied a new procedure combining multiple scan cluster detection tests to identify geographically defined areas of increased autism incidence. This procedure can serve as a first hypothesis-generating step aimed at localized environmental exposures, but would not be useful for assessing widely distributed exposures, such as household products, nor for exposures from nonpoint sources, such as traffic.

Potential impact of introduction of foot-and-mouth disease from wild pigs into commercial livestock premises in California.

Objective: To estimate potential spread of foot-and-mouth disease (FMD) if introduced from wild pigs in California and to evaluate efficacies of various control strategies.

Sample Population: Data for California livestock and from hunter surveys on wild pigs in California.

Procedures: A spatial, stochastic simulation model was used to simulate FMD epidemics that might occur if a dairy or beef herd were infected from contact with a wild pig.

A flock-tailored early warning system for low pathogenic avian influenza (LPAI) in commercial egg laying flocks.

The aim of this study was to develop and evaluate an early warning system (EWS) for commercial egg laying flocks to detect the subtle mortality and egg production changes that characterize low pathogenic avian influenza virus (LPAIV) infections. An EWS will create an alert when the recommended 'trigger point' is reached or exceeded. Previously used EWSs are based on fixed alert levels, while the proposed EWS customizes the alert level to each flock.

Identifying errors in avian influenza virus gene sequences and implications for data usage of public databases.

Public gene sequence databases have become important research tools to understand viruses and other organisms. Evidence suggests that the identifying information for some of the sequences in these databases might not belong to the sequences they are associated with. We developed two tests to conduct a comprehensive analysis of all published sequences of the hemaglutinin and neuramidase genes of avian influenza viruses (AIVs) to identify sequences that may have been misclassified.