Potential role of wildlife in the USA in the event of a foot-and-mouth disease virus incursion

Foot-and-mouth disease (FMD) is caused by foot-and-mouth disease virus (FMDV) which affects domestic and wild cloven-hoofed species. The FMD-free status of the USA and the tremendous economic impact of a virus incursion motivated the development of this evaluation of the potential role of wildlife in the event of a virus introduction. Additionally, this manuscript contains a summary of US vulnerabilities for viral incursion and persistence which focuses specifically on the possible role of wildlife. The legal movement of susceptible live animals, animal products, by-products and animal feed containing animal products pose a risk of virus introduction and spread. Additionally, the illegal movement of FMD-susceptible animals and their products and an act of bioterrorism present additional routes where FMDV could be introduced to the USA. Therefore, robust surveillance and rapid diagnostics in the face of a possible introduction are essential for detecting and controlling FMD as quickly as possible. Wildlife species and feral pigs present an added complexity in the case of FMDV introduction as they are typically not closely monitored or managed and there are significant logistical concerns pertaining to disease surveillance and control in these populations. Recommendations highlight the need to address existing knowledge gaps relative to the potential role of wildlife in FMDV introduction events

Feral Swine Disease Surveillance – National Targets and Pilot Projects

The National Feral Swine Damage Management Program (NFSP) in collaboration with the National Wildlife Disease Program (NWDP) and USDA APHIS Veterinary Services works to identify the diseases of national concern in feral swine. The current national disease surveillance program includes classical swine fever (CSF), swine brucellosis (SB), and pseudorabies (PRV). CSF is a foreign animal disease and feral swine samples collected and tested serve as part of Veterinary Services surveillance stream for this pathogen. Both SB and PRV have been eradicated from U.S. commercial swine operations; however, as they are endemic diseases in feral swine populations, monitoring of feral swine for SB and PRV is deemed important to inform the swine industry as well as other livestock entities of the potential risk of reintroduction. Wildlife Services routinely removes feral swine and collects serum (approximately 2,800 samples annually) to conduct serologic tests on these three diseases. Sampling is distributed over both space and time and is currently undertaken in 37 states of the U.S. with counties being ranked high, medium, and low priority based upon risk factors. In addition to the diseases of national concern, the NFSP supports a number of pilot projects to address disease issues that arise at a local level. In close collaboration with Wildlife Services field personnel and others on the ground, the NFSP is able to quickly and robustly identify and sample for additional pathogens of zoonotic, domestic livestock, or companion animal concern. These projects are often multi-agency collaborative efforts and include diseases such as bovine tuberculosis and chronic wasting disease

African Swine Fever

At the time of writing this chapter, a global pandemic of African swine fever (ASF) is ongoing with the virus having moved from Eastern Europe, Asia, and into the Caribbean—leaving swine production in devastation along the way. Due to the global spread of African swine fever virus (ASFV), the persistence of the virus, and the increasing number of endemic countries, this disease poses an imminent threat of introduction into North America and other countries that are currently ASF free. Throughout the chapter, we reference Eurasian wild boar (Sus scrofa) which are charismatic megafauna that are native to Europe and Asia. Wild boar were introduced into numerous areas in the southeastern United States and California by early settlers and they subsequently augmented and hybridized with established feral domestic swine (Sus scrofa) to give rise to contemporary populations of feral swine, a highly invasive species that are present across much of the United States. Feral swine are referred to by various terms, including wild hogs, feral pigs, wild boar, wild swine, razorbacks, and other regional names in North America. African swine fever has never been introduced into the United States; as such, we do not discuss feral swine in specific within the chapter. However, experimental inoculations demonstrate that feral swine are acutely susceptible to ASFV and given its current rapid global movement we anticipate similar patterns of exposure, infection, and risk amongst these populations

The National Feral Swine Program, National Strategy – The First Five Years

In 2014, through Congressional direction, the Animal Plant Health Inspection Service (APHIS) National Feral Swine Damage Management Program was created. While feral swine damage management was certainly not new to APHIS Wildlife Services, this mandate enabled a programmatic and unified approach in combating the destructive forces of feral swine throughout the United States and its territories. Recognizing the variance in environmental conditions and regulatory processes throughout the states, APHIS’ strategy is to provide resources and expertise at a national level, while allowing flexibility to manage operational activities from a local or state perspective. Having completed the first five years of this pursuit, APHIS has compiled a report which serves to describe the program and its components, ongoing collaborative research, the operational approach, and the outreach and communication campaigns. This presentation provided an overview of this report, introducing accomplishments achieved, setbacks encountered, and future considerations. The report will be electronically available on the USDA/APHIS/Wildlife Services web page at: https://www.aphis.usda.gov/aphis/ourfocus/wildlifedamag

Adaptive risk-based targeted surveillance for foreign animal diseases at the wildlife-livestock interface

Animal disease surveillance is an important component of the national veterinary infrastructure to protect animal agriculture and facilitates identification of foreign animal disease (FAD) introduction. Once introduced, pathogens shared among domestic and wild animals are especially challenging to manage due to the complex ecology of spillover and spillback. Thus, early identification of FAD in wildlife is critical to minimize outbreak severity and potential impacts on animal agriculture as well as potential impacts on wildlife and biodiversity. As a result, national surveillance and monitoring programs that include wildlife are becoming increasingly common. Designing surveillance systems in wildlife or, more importantly, at the interface of wildlife and domestic animals, is especially challenging because of the frequent lack of ecological and epidemiological data for wildlife species and technical challenges associated with a lack of non-invasive methodologies. To meet the increasing need for targeted FAD surveillance and to address gaps in existing wildlife surveillance systems, we developed an adaptive risk-based targeted surveillance approach that accounts for risks in source and recipient host populations. The approach is flexible, accounts for changing disease risks through time, can be scaled from local to national extents and permits the inclusion of quantitative data or when information is limited to expert opinion. We apply this adaptive risk-based surveillance framework to prioritize areas for surveillance in wild pigs in the United States with the objective of early detection of three diseases: classical swine fever, African swine fever and foot-and-mouth disease. We discuss our surveillance framework, its application to wild pigs and discuss the utility of this framework for surveillance of other host species and diseases

Micron-sized Spinel Crystals In High Level Waste Glass Compositions: Determination Of Crystal Size And Crystal Fraction

The compositions utilized for immobilization of high-level nuclear wastes (HLW) are controlled using glass property models to avoid the deleterious effects of crystallization in the high-level waste (HLW) vitrification melters. The type and size of the crystals that precipitate during melter operations (typically at 1150 °C) and idling (∼1000 °C) are significantly impacted by glass composition and thermal history. This study was conducted to measure the impact of melt composition and heat treatment temperature on crystal size and fraction. A matrix of 31 multi-component glasses canvasing the expected Hanford HLW compositional space was developed and the glasses fabricated, and heat treated at 850, 900, and 950 °C. The crystal amounts, as determined by X-ray diffraction, varied from 0.2 to 41.0 wt.%. Spinel concentrations ranged from 0.0 to 13.8 wt.%. One glass of the matrix did not precipitate spinel and contained 0.2 wt.% RuO2, which was assumed to be undissolved from the melting process. All compositions contained crystals in the as-quenched glass. All of the spinel-based crystals present in the glasses were less than 10 μm in diameter, as determined by scanning electron microscopy with image analysis. Composition and temperature dependent models were generated using the resulting data and the best model fit was obtained by only considering spinel concentrations (R2 = 0.87). Two glasses were unable to be characterized because of an inability to process the glass under the conditions of this study. Those glasses were utilized to give insight into a potential multi-component constraint to aid in future statistical composition designs

Feral Swine as Indirect Indicators of Environmental Anthrax Contamination and Potential Mechanical Vectors of Infectious Spores

U.S. government wor

Optimising response to an introduction of African swine fever in wild pigs

African swine fever virus (ASFv) is a virulent pathogen that threatens domestic swine industries globally and persists in wild boar populations in some countries. Persistence in wild boar can challenge elimination and prevent disease-free status, making it necessary to address wild swine in proactive response plans. In the United States, invasive wild pigs are abundant and found across a wide range of ecological conditions that could drive different epidemiological dynamics among populations. Information on the size of the control areas required to rapidly eliminate the ASFv in wild pigs and how this area should change with management constraints and local ecology is needed to optimize response planning. We developed a spatially explicit disease transmission model contrasting wild pig movement and contact ecology in two ecosystems in Southeastern United States. We simulated ASFv spread and determined the optimal response area (reported as the radius of a circle) for eliminating ASFv rapidly over a range of detection times (when ASFv was detected relative to the true date of introduction), culling capacities (proportion of wild pigs in the culling zone removed weekly) and wild pig densities. Large radii for response areas (14 km) were needed under most conditions but could be shortened with early detection (≤ 8 weeks) and high culling capacities (≥ 15% weekly). Under most conditions, the ASFv was eliminated in less than 22 weeks using optimal control radii, although ecological conditions with high rates of wild pig movement required higher culling capacities (≥ 10% weekly) for elimination within 1 year. The results highlight the importance of adjusting response plans based on local ecology and show that wild pig movement is a better predictor of the optimal response area than the number of ASFv cases early in the outbreak trajectory. Our framework provides a tool for determining optimal control plans in different areas, guiding expectations of response impacts, and planning resources needed for rapid elimination

Potential Use for Serosurveillance of Feral Swine to Map Risk for Anthrax Exposure, Texas, USA

Anthrax is a disease of concern in many mammals, including humans. Management primarily consists of prevention through vaccination and tracking clinical-level observations because environmental isolation is laborious and bacterial distribution across large geographic areas diffi cult to confi rm. Feral swine (Sus scrofa) are an invasive species with an extensive range in the southern United States that rarely succumbs to anthrax. We present evidence that feral swine might serve as biosentinels based on comparative seroprevalence in swine from historically defi ned anthrax-endemic and non–anthraxendemic regions of Texas. Overall seropositivity was 43.7% (n = 478), and logistic regression revealed county endemicity status, age-class, sex, latitude, and longitude were informative for predicting antibody status. However, of these covariates, only latitude was statistically signifi cant (β = –0.153, p = 0.047). These results suggests anthrax exposure in swine, when paired with continuous location data, could serve as a proxy for bacterial presence in specifi c areas

Risks of introduction and economic consequences associated with African swine fever, classical swine fever and foot-and-mouth disease: A review of the literature

African swine fever (ASF), classical swine fever (CSF) and foot-and-mouth disease (FMD) are considered to be three of the most detrimental animal diseases and are currently foreign to the U.S. Emerging and re-emerging pathogens can have tremendous impacts in terms of livestock morbidity and mortality events, production losses, forced trade restrictions, and costs associated with treatment and control. The United States is the world\u27s top producer of beef for domestic and export use and the world\u27s third-largest producer and consumer of pork and pork products; it has also recently been either the world\u27s largest or second largest exporter of pork and pork products. Understanding the routes of introduction into the United States and the potential economic impact of each pathogen are crucial to (a) allocate resources to prevent routes of introduction that are believed to be more probable, (b) evaluate cost and efficacy of control methods and (c) ensure that protections are enacted to minimize impact to the most vulnerable industries. With two scoping literature reviews, pulled from global data, this study assesses the risk posed by each disease in the event of a viral introduction into the United States and illustrates what is known about the economic costs and losses associated with an outbreak