Due to the ongoing global outbreak of influenza A (H5N1) in birds, and recent infections in dairy cattle and humans in the United States, the Centers for Disease Control and Prevention (CDC) and the California Department of Public Health (CDPH) are encouraging enhanced surveillance and continued testing for influenza this summer. 

Influenza A (H5N1) is believed to pose a low risk to human health. However, because of the possibility that avian influenza viruses could gain the ability to spread easily between people, monitoring for human infection is important for public health. Testing for influenza and subtyping all influenza A positives over the summer is important so public health officials can track the influenza A subtypes circulating in the community. 

CDPH recommends that physicians report any suspected case of novel, avian or variant influenza to their local health department immediately, and test for influenza in patients with respiratory illness and relevant animal exposures that could increase risk for influenza A (H5N1). CDPH also advises providers to test severely ill patients irrespective of exposure history.  

To date, more than 90 million poultry in the U.S. have been affected by the H5N1 outbreak, making it the worst domestic poultry outbreak on record. Influenza A has also been detected in dairy cattle in Texas, and three dairy farm workers have experienced mild infections due to exposure to infected dairy cattle. No cases of human-to-human transmission have been identified.  

For more information, see the CDPH Health Alert.