Feral Swine Diseases
Feral swine are best known for their destruction to agriculture, such as row crops, forestry, livestock, and pastures. However, they also cause great risks to health and safety by harboring and transmitting diseases. They are known to carry or transmit at least 30 diseases (viral and bacterial) as well as host a minimum of 37 parasites that can affect humans, pets, wildlife, and livestock.
Introduction of certain diseases into domestic livestock populations would have a severe economic consequence. Nationally, costs to quarantine herds, monitoring disease progression, and treatment of infected animals would amount to billions of dollars across the United States. In Georgia, according to the the $792 million dollar livestock industry (including cattle, goats, domestic pigs, and horses, according to the 2017 Census of Agriculture) would be at risk.
To prevent this potentially devastating impact, the United States Department of Agriculture (USDA) is involved in disease management and surveillance, research, education, and outreach for diseases of feral swine through the National Wildlife Disease Program. Currently USDA Wildlife Services conducts nationwide surveillance for three different diseases: classical swine fever, pseudorabies, and swine brucellosis.
Classical swine fever is a contagious systemic viral disease that was eradicated from the United States in 1978, and now is considered a foreign animal disease (FAD). The reason for continued surveillance is to protect domestic swine production by providing an early warning, as a reintroduction into domestic swine herd would be devastating to the pork industry.
Pseudorabies is an infectious disease caused by a herpesvirus that impacts livestock and pets, including cattle, dogs, cats, sheep, and goats. Currently, domestic swine are considered pseudorabies-free. While there is no indication pseudorabies has an adverse effect on wild populations, infection in domestic swine often results in abortions or piglet deaths and livestock more broadly are also at risk. Although an important disease in livestock and pets, humans are not affected by this disease.
Swine brucellosis poses no known adverse effect to wild swine populations; however, it can affect the brucellosis-free status of the domestic swine. The disease is caused by the bacteria Brucella suis and is primarily spread during reproduction. Unlike pseudorabies, swine brucellosis can be transmitted to humans. Infection typically occurs while handling, field dressing, or butchering feral swine. While human cases are rare, individuals handling and preparing feral swine should be advised to wear proper protective gloves, practice good sanitation, and thoroughly cook meat.
Through Georgia’s National Wildlife Disease Program, over a quarter of feral swine samples from April 1, 2020 through May 2022 tested positive for pseudorabies or swine brucellosis. Data within the Feral Swine Control and Eradication Pilot Project in Calhoun County show even higher incidence of disease. Below is a chart with the total number of samples and results USDA Wildlife Services collected for the entire state of GA for the time frame of April 1, 2020 to May 16, 2022 (Chart 1). Also included is a chart with the total number of samples taken within the same time frame and results collected from the project area, Calhoun County, Georgia (Chart 2).
USDA Wildlife Services took 649 samples from feral swine across the state of Georgia. 177, or 27.3%, of those samples came back as positive for pseudorabies. 174, or 26.8%, samples came back as positive for swine brucellosis. Classical swine fever has had zero positives, hence there are no results listed here.
Chart 1: USDA Wildlife Services (WS) feral swine sample results statewide.
USDA Wildlife Services took 73 samples from feral swine in the project area of Calhoun County, Georgia. 39, or 53.4%, of those samples came back as positive for pseudorabies. 34, or 46.6%, samples came back as positive for swine brucellosis. Classical swine fever has had zero positives, hence there are no results listed here.
Chart 2: USDA Wildlife Services feral swine sample results in the project area, Calhoun County.
Data shows that disease is prevalent in feral swine populations and prevention of spread to domestic livestock and humans is imperative. Where feral swine and livestock interact, the best means of disease prevention is feral swine population control and exclusion of feral swine from feeding and watering areas. The illegal translocation of feral swine can also spread these diseases to both livestock and humans.
Hunters should also follow these simple measures to avoid infection when handling or field dressing feral swine:
Wear latex or nitrile gloves; pathogens can enter the body through cuts on hands or torn cuticles.
Avoid splashing body fluids into your eyes or mouth.
Wash your hands thoroughly after field dressing and processing meat, even if you wear gloves.
Thoroughly clean and disinfect work areas and tools used to dress and butcher feral swine.
Dispose of animal remains, used gloves, and other materials properly. Animal remains should not be left for scavengers, nor should they be fed to dogs. Depending upon your jurisdiction, several methods of appropriate disposal may be considered. Check with your local health department or state wildlife agency.
Follow correct refrigeration, freezing, and cooking methods. Freezing to 0°F will render bacteria inactive but will not destroy them; once thawed, bacteria can again become active. Also, do not rely on home freezing to destroy Trichina and other parasites. Thorough cooking will destroy all parasites and kill bacteria. Cook feral swine meat to an internal temperature of 165°F to 170°F.
To learn more about USDA Wildlife Services feral swine disease surveillance, visit their website. To contact the Georgia Feral Swine Partnership or to learn more information, visit Georgia Feral Swine. The Albany Area Feral Swine Control and Eradication Pilot Project is led by the Flint River Soil and Water Conservation District.
This material is based upon work supported by the U.S. Department of Agriculture, under Agreement number NR204310XXXXG001.