In the United States, the non-native and invasive feral swine (Sus scrofa) population has quadrupled over the past 10 years and is currently estimated to be approximately 4 million animals ranging across at least 37 states.  As the feral swine population expands and feral swine hunting becomes more popular, there is increased interaction and greater potential for disease transmission among feral swine, humans, commercial swine, and wildlife.

From 2007 to 2010, we conducted a disease survey (pdf) of over 600 feral swine across 13 North Carolina counties (where the majority of the state’s commercial swine production occurs). Although a variety of diseases were tested, the most notable results were the detection of the bacteria Brucella suis. Brucella suis is typically screened for by the National Wildlife Disease Program and, until this research, feral swine were antibody-negative in eastern North Carolina. Currently, B. suis does not occur in US domestic swine operations.

The presence of B. suis in a feral swine population that is routinely hunted raises concern about disease transmission to humans. In pigs, B. suis is a bacteria that can cause abortion in pregnant females, reduced milk production, and infertility. Importantly, B. suis is zoonotic (can be transferred from wildlife to humans; once transmitted it is called brucellosis) and can be transmitted to humans through cuts on the skin from handling the infected animals or inhaling the waste product of the animal.

In humans, brucellosis causes a variety of symptoms, such as fever, weight loss, fatigue, weakness, chills, joint pain, headaches and depression. Brucellosis can develop weeks to months after exposure, can last for days to months, and can be debilitating if not treated. Recent cases of B. suis infection in feral swine hunters were linked to butchering of swine but not to consumption of the meat. Diagnosing brucellosis can be difficult because of the wide-ranging and non-specific symptoms. Therefore, it is very important to inform your health care provider if you have come in contact with feral swine. Once identified, brucellosis is treated with antibiotics.

While in the field, there are some simple precautions that hunters should take to protect themself. First, hunters should always were long sleeves, gloves, and eye protection when cleaning any game animal. Your hands may have small cuts and cracks that can provide points for infectious diseases to enter your body. Further, avoiding unprotected direct contact with blood, fecal matter, the brain and spinal cord, and organs will help minimize risks. After cleaning the animal, be sure to clean and disinfect all knives, clothing, or cleaning surfaces and absolutely make sure to wash your hands frequently and carefully with soap and water. Additionally, B. suis transmission can be prevented by properly cooking the meat.

I hope you continue to follow this blog. Next week, I will be highlighting more of our research on feral swine. Specifically, Toxoplasma gondii and Trichinella spp.

Also, I encourage you to ask questions. I will answer them in upcoming blogs.

Image copyright L. Snidow

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4 thoughts on “Feral Swine and Brucellosis: How Hunters Can Minimize Risk

  1. Great article. Thanks for posting. I’m hunting Javelina next week here in AZ. Have you come across any reports that I should be concerned about for Arizona?

    1. Hello TSquare, I did a quick search and found a few published studies on javelina and diseases in Arizona. There are a few minor things that javelina can have including fungal dermatitis, external, and internal parasites. Most of these are common to all wildlife species.

      Javelina, like any mammal, can contract the rabies virus. In almost all cases javelina will show symptoms which include foaming at the mouth, alterations in behavior (aggression or fearfulness), paralysis, and lethargy. Rabies is most often but not exclusively transmitted through contact with the saliva, brain, nerve tissue, eyes, nose, and mouth. Although unlikely, make sure you do not get bit. If you happen to get bit, make sure to seek medical attention immediately. Also, if possible, the animal should be sent to a laboratory for rabies testing. The above is a simple discussion of a very complex disease.

      Javelina are known to have distemper, which can be transmitted to pets. Humans can carry distemper but will not show any symptoms. In 1989, a paper detected distemper in 58% of javelina serum samples tested which means it is very common. The authors suggested that recovery post-exposure is common.

      Salmonellosis (caused by the bacteria Salmonella) has been found in many species including birds, mammals, reptiles, amphibians, and fish. I found a published study that described a large scale mortality event of javelina in 2004. Over a hundred individuals were found dead and the researchers determined that 47% of the individuals had various Salmonella strains. However, javelina spend a lot of time rooting in the soil and normal exposure to Salmonella is normal and may not have been the ultimate reason for the deaths discussed in the study. Symptoms include diarrhea, fever, dehydration, inability to walk, and death. Animals may remain very close to a water source.

      I would be most concerned with Salmonella. Take precautions when cleaning your javelina. As mentioned above, wear disposable gloves and protective clothing when skinning and butchering the animal. Absolutely, try to avoid unprotected contact with the feces, brain, spinal cord, and blood. After cleaning the animal, be sure to clean and disinfect all knives, clothing, or cleaning surfaces and absolutely make sure to wash your hands thoroughly with soap and water. Additionally, make sure to properly cook the meat.

      Good luck hunting and let me know how you do!

    1. Hi Dave 11954, Freezing will not kill the bacteria (Brucella suis). In fact, the bacteria can survive freezing temperatures for up to 2 years. Also, smoking, drying and pickling will not kill the bacteria.

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