What is pseudorabies?

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Minnesota Board of Animal Health Reportable Disease of the Month Header

February, 2017


Pigs inside a barn.

What is it? Pigs are the natural host for this viral disease (contagious herpesvirus), and it can also affect other mammals, like cattle, sheep, goats, cats, dogs, and wild animals. Younger animals die of the disease more frequently than older animals, often within two to three days of infection. Older animals will get sick and usually recover within a week or two, although some occasionally die. The U.S. has a pseudorabies eradication program to protect livestock from the disease, which was last found in a commercial swine herd in 2003.

How is it transmitted? The virus mainly moves between animals through direct contact with an infected animal. Nose-to-nose is believed to be the most common route leading to infection. Studies point to environmental transmission, including water, also being a risk because the virus can survive for short periods of time on equipment and even in the air, if conditions are right.

What are the signs in animals? Age is an important factor in identifying the signs of a pseudorabies infected animal. Weight loss is a common sign in animals of any age and unfortunately, the first sign in younger animals may often be death. Older pigs may exhibit fever, sneezing, loss of appetite, and other respiratory issues. Non-swine species will have similar signs, and often have an irritated area on their skin that they continually itch. The itchy patch of skin is the reason pseudorabies may also be known as “mad itch.”

How is it diagnosed? Diagnosis in young swine and other animal species is frequently conducted after the animal already died from the disease. To confirm the disease, veterinarians collect blood samples and conduct a serologic test. This type of testing works by looking for antibodies produced by the animal’s immune system, which show scientists if the animal’s immune system was responding to an infection.

What is the treatment? There is no standard treatment available for pseudorabies. However, vaccination is the best way to reduce the symptoms of the disease and reduce the risk of it spreading between animals.

How can it be prevented? In addition to vaccination, all new animals entering a herd should be tested before being allowed into the herd. Approximately 20-percent of feral swine in the U.S. are seropositive (a positive test result for exposure to a virus in the blood). The U.S. has a surveillance program in place to monitor pseudorabies in wild pigs. This program helps by keeping wild and domestic herds separate to reduce the risk of disease transmission.

Is there a risk to people? There have been no reported cases or symptoms in people. However, proper biosecurity should always be practiced to protect animals, their environment, and the people working in their environment.