Classical Swine Fever Surveillance in Feral Swine

Diseases such as classical swine fever (CSF) and foot-and-mouth disease have been eradicated in the United States, but possible reintroductions merit the development of an enhanced surveillance system. Important foreign animal or transboundary diseases like these pose a significant risk to the health of wildlife and livestock in the United States. Wildlife Services (WS) performs surveillance in targeted feral swine (Sus scrofa) populations as part of a comprehensive United States Department of Agriculture, Animal and Plant Health Inspection Service effort to demonstrate disease-free status in our nation\u27s livestock and wildlife. Surveillance is based on risk assessments which identify high risk states and the vicinity of feral swine to transitional or commercial swine production facilities. During 2007 and 2008, WS sampled and tested (n = 3661) feral swine. CSF was not detected in feral swine in the United States through this surveillance effort

Dissecting a wildlife disease hotspot: the impact of multiple host species, environmental transmission and seasonality in migration, breeding and mortality

Avian influenza viruses (AIVs) have been implicated in all human influenza pandemics in recent history. Despite this, surprisingly little is known about the mechanisms underlying the maintenance and spread of these viruses in their natural bird reservoirs. Surveillance has identified an AIV ‘hotspot’ in shorebirds at Delaware Bay, in which prevalence is estimated to exceed other monitored sites by an order of magnitude. To better understand the factors that create an AIV hotspot, we developed and parametrized a mechanistic transmission model to study the simultaneous epizootiological impacts of multi-species transmission, seasonal breeding, host migration and mixed transmission routes. We scrutinized our model to examine the potential for an AIV hotspot to serve as a ‘gateway’ for the spread of novel viruses into North America. Our findings identify the conditions under which a novel influenza virus, if introduced into the system, could successfully invade and proliferate

Dissecting a wildlife disease hotspot: the impact of multiple host species, environmental transmission and seasonality in migration, breeding and mortality

Avian influenza viruses (AIVs) have been implicated in all human influenza pandemics in recent history. Despite this, surprisingly little is known about the mechanisms underlying the maintenance and spread of these viruses in their natural bird reservoirs. Surveillance has identified an AIV ‘hotspot’ in shorebirds at Delaware Bay, in which prevalence is estimated to exceed other monitored sites by an order of magnitude. To better understand the factors that create an AIV hotspot, we developed and parametrized a mechanistic transmission model to study the simultaneous epizootiological impacts of multi-species transmission, seasonal breeding, host migration and mixed transmission routes. We scrutinized our model to examine the potential for an AIV hotspot to serve as a ‘gateway’ for the spread of novel viruses into North America. Our findings identify the conditions under which a novel influenza virus, if introduced into the system, could successfully invade and proliferate

Individual-Level Antibody Dynamics Reveal Potential Drivers of Influenza A Seasonality in Wild Pig Populations

Swine are important in the ecology of influenza A virus (IAV) globally. Understanding the ecological role of wild pigs in IAV ecology has been limited because surveillance in wild pigs is often for antibodies (serosurveillance) rather than IAVs, as in humans and domestic swine. As IAV antibodies can persist long after an infection, serosurveillance data are not necessarily indicative of current infection risk. However, antibody responses to IAV infections cause a predictable antibody response, thus time of infection can be inferred from antibody levels in serological samples, enabling identification of risk factors of infection at estimated times of infection. Recent work demonstrates that these quantitative antibody methods (QAMs) can accurately recover infection dates, even when individual-level variation in antibody curves is moderately high. Also, the methodology can be implemented in a survival analysis (SA) framework to reduce bias from opportunistic sampling. Here we integrated QAMs and SA and applied this novel QAM–SA framework to understand the dynamics of IAV infection risk in wild pigs seasonally and spatially, and identify risk factors. We used national-scale IAV serosurveillance data from 15 US states. We found that infection risk was highest during January– March (54% of 61 estimated peaks), with 24% of estimated peaks occurring from May to July, and some low-level of infection risk occurring year-round. Time-varying IAV infection risk in wild pigs was positively correlated with humidity and IAV infection trends in domestic swine and humans, and did not show wave-like spatial spread of infection among states, nor more similar levels of infection risk among states with more similar meteorological conditions. Effects of host sex on IAV infection risk in wild pigs were generally not significant. Because most of the variation in infection risk was explained by state-level factors or infection risk at long-distances, our results suggested that predicting IAV infection risk in wild pigs is complicated by local ecological factors and potentially long-distance translocation of infection. In addition to revealing factors of IAV infection risk in wild pigs, our framework is broadly applicable for quantifying risk factors of disease transmission using opportunistic serosurveillance sampling, a common methodology in wildlife disease surveillance. Future research on the factors that determine individual-level antibody kinetics will facilitate the design of serosurveillance systems that can extract more accurate estimates of time-varying disease risk from quantitative antibody data

USDA and State/Tribal Cooperator Summary for 2006/2007 National Early Detection System for HPAI in Wild Migratory Birds: Accomplishments, Findings, and Future Direction

In late 2005, at the request of the Homeland Security Council\u27s Policy Coordinating Committee for Pandemic Influenza Preparedness, the United States Departments of Agriculture (USDA) and Interior began developing a United States Interagency Strategic Plan for the early detection of highly pathogenic avian influenza (HPAI) introduction into North America by wild migratory birds. This plan was stepped down by various regional, state, and tribal entities and was implemented nationwide in mid-2006. USDA funded Federal, State, and Tribal cooperators began with a goal of collecting over 75,000 surveillance samples from wild migratory birds during the 2006/2007 surveillance period. The 2006 accomplishments, findings, and Al surveillance results are reported. The USDA\u27s HPAI surveillance strategies and goals are discussed for the 2007 sampling season

Identification of \u3ci\u3eBrucella\u3c/i\u3e spp. in feral swine (\u3ci\u3eSus scrofa\u3c/i\u3e) at abattoirs in Texas, USA

Various tissues, nasal swabs, urine and blood samples were collected from 376 feral swine at two federally inspected abattoirs in Texas during six separate sampling periods in 2015. Samples were tested for Brucella spp. by culture and serology. Brucella spp. were cultured from 13.0% of feral swine, and antibodies were detected in 9.8%. Only 32.7% of culture-positive feral swine were also antibody positive, and 43.2% of antibody-positive feral swine were culture positive. Approximately, the same number of males (14.0%) and females (12.1%) were culture positive, and slightly more males (10.5%) than females (8.7%) were antibody positive. Our results indicate that serology likely underestimates the prevalence of feral swine infected, and that those who come in contact with feral swine should be aware of the symptoms of infection with Brucella spp. to ensure prompt treatment

LIMITED ANTIBODY EVIDENCE OF EXPOSURE TO MYCOBACTERIUM BOVIS IN FERAL SWINE (\u3ci\u3eSUS SCROFA\u3c/i\u3e) IN THE USA

Bovine tuberculosis is a chronic disease of cattle (Bos taurus) caused by the bacterium Mycobacterium bovis. Efforts have been made in the US to eradicate the disease in cattle, but spillover into wildlife and subsequent spillback have impeded progress in some states. In particular, infection in white-tailed deer (Odocoileus virginianus) has been followed by infection in cattle in some Midwestern states. Infection has also been documented in feral swine (Sus scrofa) on the Hawaiian island of Molokai and in various European countries, but no large-scale survey of antibody exposure to the bacteria has been conducted in feral swine in the US. We tested 488 sera from feral swine collected near previously documented outbreaks of bovine tuberculosis in cattle and captive cervids, in addition to 2,237 feral swine sera collected across the US from 1 October 2013 to 30 September 2014. While all but one of the samples were antibody negative, the results are important for establishing baseline negative data since feral swine are capable reservoirs and could be implicated in future outbreaks of the disease

Influenza A Virus H5–specific Antibodies in Mute Swans (\u3ci\u3eCygnus olor\u3c/i\u3e) in the USA

The use of serologic assays for influenza A virus (IAV) surveillance in wild birds has increased because of the availability of commercial enzyme-linked immunosorbent assays (ELISAs). Recently, an H5-specific blocking ELISA (bELISA) was shown to reliably detect H5-specific antibodies to low- and highpathogenic H5 viruses in experimentally infected waterfowl. Mute Swans (Cygnus olor) were frequently associated with highly pathogenic H5N1 outbreaks in Europe and may have a similar role if highly pathogenic H5N1 is introduced into North America. We measured the prevalence of antibodies to the nucleoprotein and H5 protein in Mute Swans using three serologic assays. We collected 340 serum samples from Mute Swans in Michigan, New Jersey, New York, and Rhode Island, US. We detected antibodies to the IAV nucleoprotein in 66.2% (225/340) of the samples. We detected H5-specific antibodies in 62.9% (214/340) and 18.8% (64/340) using a modified H5 bELISA protocol and hemagglutination inhibition (HI) assay, respectively. The modified H5 bELISA protocol detected significantly more positive samples than did the manufacturer’s protocol. We also tested 46 samples using virus neutralization. Neutralization results had high agreement with the modified H5 bELISA protocol and detected a higher prevalence than did the HI assay. These results indicate that North American Mute Swans have high nucleoprotein and H5 antibody prevalences

Widespread Detection of Antibodies to Eastern Equine Encephalitis, West Nile, St. Louis Encephalitis, and Turlock Viruses in Various Species of Wild Birds from Across the United States

Wild birds serve as amplifying hosts for many arboviruses, and are thought to be responsible for introducing these viruses into new areas during migration as well as reintroducing them to places where winter temperatures disrupt mosquito-borne transmission. To learn more about four mosquito-borne arboviruses of concern to human or animal health, we tested sera from 997 wild birds of 54 species and 17 families across 44 states of the United States collected from January 1, 2013, through September 30, 2013. Samples were tested for antibody against eastern equine encephalitis, St. Louis encephalitis, West Nile, and Turlock viruses using plaque reduction neutralization tests with an endpoint of 80% or greater. Of the 333 (33.4%) birds that tested positive for antibody to at least one arbovirus, 29.7% were exposed to two or more arboviruses. Exposure to all four arboviruses was detected in Canada geese, double-crested cormorants, mallards, mute swans, laughing gulls, and American coots. Our results suggest that exposure to arboviruses is widespread in the United States across a diversity of wild bird species

Widespread Detection of Antibodies to Eastern Equine Encephalitis, West Nile, St. Louis Encephalitis, and Turlock Viruses in Various Species of Wild Birds from Across the United States

Wild birds serve as amplifying hosts for many arboviruses, and are thought to be responsible for introducing these viruses into new areas during migration as well as reintroducing them to places where winter temperatures disrupt mosquito-borne transmission. To learn more about four mosquito-borne arboviruses of concern to human or animal health, we tested sera from 997 wild birds of 54 species and 17 families across 44 states of the United States collected from January 1, 2013, through September 30, 2013. Samples were tested for antibody against eastern equine encephalitis, St. Louis encephalitis, West Nile, and Turlock viruses using plaque reduction neutralization tests with an endpoint of 80% or greater. Of the 333 (33.4%) birds that tested positive for antibody to at least one arbovirus, 29.7% were exposed to two or more arboviruses. Exposure to all four arboviruses was detected in Canada geese, double-crested cormorants, mallards, mute swans, laughing gulls, and American coots. Our results suggest that exposure to arboviruses is widespread in the United States across a diversity of wild bird species