Influenza A H3N2 variant (H3N2v)

H3N2v is a non-human influenza virus that normally circulates in pigs and that can infect humans. Viruses that normally circulate in pigs are “swine influenza viruses.”  When these viruses infect humans, they are termed “variant” viruses.  In 2011, a specific H3N2 virus was detected with genes from avian, swine and human influenza viruses and the 2009 H1N1 pandemic virus M gene. The virus was circulating in pigs in 2010 and was first detected in people in 2011.  There were 12 human illnesses with this virus, in 2011; most were associated with exposure to pigs.  Since July 2012, an increasing number of illnesses due to influenza A H3N2v have been identified in several states.  Most of the recent illnesses due to H3N2v have occurred among people that had contact with pigs.  In a small number of cases, the H3N2v virus seems to have spread from person-to-person.

For a list of cases identified in the United States, refer to the case count table, located on the Centers for Disease Control (CDC) web page. 

Updated reports on the national H3N2v situation can be found on CDC’s Influenza A (H3N2) Variant Virus web page.

How can a person catch the flu from a pig?

H3N2v virus is spread from infected pigs to humans in the same way that seasonal influenza (flu) viruses spread between people. Mainly, the spread of flu happens when droplets infected with flu - spread through the air after an infected pig coughs or sneezes - land in your nose or mouth, or when the droplets are inhaled. You might also get the flu by touching something that has flu virus on it and then touching your own eyes, nose, or mouth. A third way to possibly get the flu is to breath in dust containing flu virus. 

What are the symptoms of H3N2v?

The symptoms and severity of H3N2v illness have been similar to seasonal flu, including fever, cough, runny nose, and possibly other symptoms, such as body aches, vomiting, or diarrhea.

People who are considered at high risk for developing flu-related complications are the following:  Children less than five years of age (especially children less than two years of age), adults 65 years of age and older, pregnant women, and people with certain chronic medical conditions like asthma, diabetes, heart disease, weakened immune systems, and neurological conditions. If you develop flu symptoms after having direct or close contact with swine, contact your doctor and tell them your symptoms and about your contact with pigs.

Actions You Can Take to Prevent the Spread of Flu Between People:

The Oklahoma State Department of Health recommends you take everyday preventive actions to reduce the risk of infection and spread of flu viruses between people, including H3N2v, such as:

• Cover your nose and mouth with a tissue when you cough or sneeze.  Throw the tissue in the trash after you use it.
• Wash your hands often with soap and water, especially immediately after you cough or sneeze. If soap and water are not available, an alcohol-based hand rub may be used.
• Avoid touching your eyes, nose or mouth. Germs spread that way.
• Try to avoid close contact with sick people.
• If you are sick, stay home from work or school until your illness is over.

Actions You Can Take to Prevent the Spread of Flu between Pigs and People:

The Oklahoma State Department of Health recommends you take the following preventive actions to reduce the risk of infection with flu virus from pigs, including H3N2v, such as:

• Don’t take food or drink into pig areas; don’t eat, drink or put anything in your mouth in pig areas.
• Don’t take toys, pacifiers, cups, baby bottles, strollers, or similar items into pig areas.
• Wash your hands often with soap and running water before and after exposure to pigs. If soap and water are not available, use an alcohol-based hand rub.
• Avoid close contact with pigs that look or act ill.
• Take protective measures if you must come in contact with pigs that are known or suspected to be sick. This includes minimizing contact with pigs and wearing personal protective equipment like protective clothing, gloves and masks that cover your mouth and nose when contact is required.
• Watch your pig (if you have one) for signs of illness and call a veterinarian if you suspect it might be sick.
• Avoid contact with pigs if you have flu-like symptoms. Wait 7 days after your illness started or until you have been without fever for 24 hours without the use of fever-reducing medications, whichever is longer. If you must have contact with pigs while you are sick, take the protective actions listed above.

External H3N2v Resources:

What People Who Raise Pigs Need to Know About Influenza (CDC)

Fact Sheet:  Prevent the Spread of the Flu between People and Pigs at Fairs (CDC)

Poster:  How to be Safe Around Animals (NASPHV)

Poster:  Hand Washing at Animal Exhibits (NASPHV)

H3N2v Information for Clinicians (CDC)

H3N2v Treatment Information for Clinicians (CDC)

H3N2v Information for Schools (CDC)