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What is Influenza A Virus in Swine (IAV-S)

There are three subtypes of influenza A viruses that are commonly found in United States swine:  H1N1, H1N2, and H3N2. Most of the influenza viruses that circulate in pigs are different from the ones that circulate in people. However, pigs may occasionally become infected by influenza viruses found in people or birds.

Pigs share influenza viruses the same way humans share influenza viruses, through close contact, coughing, and sneezing. It is also possible that contaminated objects (such as farming equipment) can spread the virus from infected animals to non-infected animals.

Influenza viruses are common in swine, usually causing a high rate of infection but few deaths. In many instances swine show no signs of illness. Animals typically begin getting sick 1–3 days after being infected with the virus. Symptoms may include coughing or barking, sneezing, high fever, difficulty breathing, runny nose, not eating, or not wanting to get up and move around.

If you see any of these signs in your pigs, try to isolate the sick animal(s) from the rest of the herd, provide supportive care, and contact your veterinarian.

Vaccination prior to onset of illness with either commercially available influenza vaccines or autogenous influenza vaccines is often at least partially effective in reducing clinical signs and virus shedding.  However, because these viruses can change rapidly, vaccination can sometimes fail to provide a satisfactory level of protection.

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