Feral Friday: Feral Swine Diseases

By Taylor Renton, AmeriCorps Member, MUCC Wildlife Habitat Volunteer Coordinator
Feral Sqine Sick USDA Wildlife Services biologist taking samples for disease testing
Feral swine are not only terrible for Michigan’s agricultural and natural resources, but they carry many diseases that can be passed to domestic animals and even humans. The state of Michigan exports a large amount of pork, so a disease infecting the commercial swine industry could be devastating. If you read last week’s article then you know about the “Shoot on Sight” policy for killing feral swine. But it is important that you report any kills to the USDA Wildlife Services (517-336-1928) so they can come out and test the animal for diseases. Currently there are four main diseases Wildlife Services are running surveillance for, along with TB in areas close to the TB zone. Below is a summary of the diseases they are on the lookout for and how you can protect yourself.
Classical swine fever is also known as “hog cholera”. It was eradicated from domestic swine in the United States in the 70s and is now considered a foreign disease. While it is no longer found in our county, the possibility of classical swine fever or foot and mouth disease (another eradicated disease) returning could be more devastating than ever before. Because of the skyrocketing feral swine populations across the country, an outbreak of one of these two diseases could be impossible to contain. Wildlife Services tests for classical swine fever in every pig as surveillance for early detection of the disease.
Swine Brucellosis is another disease that feral swine are tested for. It is caused by bacteria, but not the same one that can affect cattle and dogs. The swine version attacks the reproductive organs in pigs causing abortions, still born or weak piglets, infertility, and many other issues. The Brucella bacteria can also infect humans who handle feral pigs. The disease causes flu-like symptoms and can be difficult to diagnose. Luckily swine brucellosis has not been detected in Michigan yet.
Pseudorabies is caused by a herpes virus, and it has been found in Michigan feral swine. Since 2006, 144 feral pigs have been sample and 10 were found positive with pseudorabies. Feral swine rarely show symptoms of the infection but domestic swine often get fatal infections. It affects younger pigs more severely while adults usually survive infections and pass it on. Commercial swine in Michigan are currently pseudorabies free, and it would be terrible for the disease to be reintroduced. In commercial swine, the infection of pseudorabies causes pregnant sows to abort their fetuses. Other mammals such as cattle and dogs can become infected by pseudorabies. It is commonly known as “mad itch” and is nearly 100% fatal.
Swine Influenza also known as “Swine Flu” is a respiratory disease in swine caused by type A influenza viruses. It regularly causes outbreaks in pigs but the viruses can sometimes sporadically infect humans. Like the name suggests, it causes flu-like symptoms in people. The USDA Wildlife Services runs surveillance for this disease also.
In areas close to the TB region, the USDA Wildlife Services had started testing feral swine for Bovine TB. Pigs can also be carriers of the disease but there have luckily been no positives in Michigan so far.
In order to protect yourself from these diseases it is important to:
1- Wear rubber gloves when handling feral swine
2- Wash with soap immediately after
3- Be sure to cook the meat properly (reach an internal temperature of 170 degrees)
Call USDA Wildlife Services (517-336-1928) as soon as possible after killing a pig! Wait to gut the animal and someone will be out as quickly as possible to take blood sample and check for diseases. Wildlife Services can also dispose of the pig for you if you don’t want to keep it.

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