The 2022 fair season in West Virginia is underway. Past agricultural fairs across the United States have been linked to human infections caused by variant influenza A viruses that are commonly found in swine. Three individuals have tested positive for influenza A (H3N2v) after attendance at the recent Jackson County, West Virginia Junior Fair. All three cases occurred in individuals younger than 18 years and did not require hospitalization. These are the first human infections with a flu virus from pigs identified in the United States during 2022. Recent reports of an increase in swine flu outbreaks in pigs in the United States suggest the risk of exposure and infection with these viruses may be higher than usual this fair season.
Swine influenza virus is a respiratory illness caused by influenza A viruses that regularly circulate in pigs. Swine flu viruses do not usually infect humans, but human infections can occur, usually after direct or indirect contact with pigs. No ongoing community transmission between humans has been identified during this outbreak. General information about swine influenza and variant swine influenza is available at http://www.cdc.gov/flu/swineflu/index.htm.
Recommendations for Healthcare Providers
Remain vigilant and consider the possibility of human infection with a variant virus when a patient presents with influenza-like illness (fever over 100°F with cough and/or sore throat) who attended a fair or reports to have had contact with swine. The incubation period ranges from one to four days. Possible exposures include showing, raising, feeding, or providing care to swine, visiting a swine farm, walking through a swine barn, or having close contact with an ill person who had recent swine exposure.
- Human infections with novel influenza A are a Category I disease, immediately reportable to the local health department. Novel influenza A viruses are different from current seasonal viruses circulating in people and include variant flu viruses. Any suspected novel influenza infection in humans should be reported to limit potential exposures and ensure the virus is not being transmitted in an efficient ongoing way between people as these viruses have the potential to cause a flu pandemic.
- Reverse-transcription polymerase chain reaction (RT-PCR) testing for influenza should be considered for patients with influenza-like illness prior to the start of traditional influenza season in October.
- RT-PCR testing for influenza should be considered throughout the year for patients with influenza-like illness reporting recent swine exposure and for those who can be epidemiologically linked to confirmed cases of variant influenza.
- Commercial laboratories are unable to distinguish between seasonal and variant influenza viruses, therefore healthcare providers should notify their local health department of any suspected variant virus infections as soon as The local health department can arrange for testing through the state public health laboratory, Office of Laboratory Services (OLS) by coordinating with the Office of Epidemiology and Prevention Services (OEPS). Instructions on specimen collection including the specimen test requisition form can be found at: https://dhhr.wv.gov/ols/forms/Pages/default.aspx.
- For persons suspected of having a variant virus infection and who are hospitalized, have severe or progressive illness, or are in a high-risk group, empiric antiviral treatment should be started as soon as possible, without waiting for the results of influenza testing. Additional guidance for healthcare providers on human infection with variant viruses can be found at: https://www.cdc.gov/flu/swineflu/interim-guidance- variant-flu.htm