August 5, 2022—CDC has reported the first human infection with an influenza (flu) virus that usually spreads in pigs occurring during 2022. The person had direct contact with pigs at an agricultural fair, where pigs tested positive for flu A. Recent reports of an increase in swine flu outbreaks in pigs in the U.S. suggest the risk of exposure and infection with these viruses may be higher than usual this fair season, which can last into the fall. CDC recommends people take precautions around swine, including in the fair setting.
Every year, there are rare sporadic human infections with flu viruses that usually spread in pigs. When found in people, these are called “variant flu virus” infections and designated with the letter “v” after the subtype. Variant flu virus infections are usually associated with contact with pigs, often at agricultural fairs. While these types of infections usually cause mild illness, they are concerning because they can cause severe illness, especially in people at higher risk of serious flu complications, and because of their potential to cause a flu pandemic.
The first variant flu virus infection of 2022 was reported by West Virginia and occurred in a person younger than 18 years who participated in an agricultural fair and had contact with pigs. An investigation is still ongoing but findings to date include:
- The infected person was not hospitalized and is recovering from their illness.
- The variant virus is a flu A H3N2v virus, based on RT-PCR testing done at CDC.
- Pigs at this fair tested positive for flu A.
- There have been reports of respiratory illness among other people who attended the same agricultural event. Specimens from other patients are being forwarded to CDC for additional testing.
- To date, no person-to-person spread of this virus has been confirmed.
Agricultural fairs take place across the United States every year, primarily during the summer months and into early fall. Many fairs have swine exhibitions, where pigs from different places come into close contact with each other and with people. These venues may increase the risk of spread of flu viruses among pigs and between pigs and people due to these interactions.