The Centers for Disease Control and Prevention (CDC) has confirmed a human infection with avian influenza A(H5N1) (H5N1 bird flu) in a child in California. This is the first reported avian influenza H5 virus infection in a child in the United States. Consistent with previously identified human cases in the United States, the child reportedly experienced mild symptoms and received flu antivirals. There were low levels of viral material detected in the initial specimen collected, and follow-up testing of the child several days later was negative for H5 bird flu but was positive for other common respiratory viruses. The child is recovering from their illness. An investigation by the California Department of Public Health (CDPH) into the child’s possible H5N1 exposure source is ongoing.

During CDPH’s investigation, all household members reported having symptoms and specimens were collected from those people. All test results from members of the household were negative for H5 bird flu, and some family members were positive for the same common respiratory viruses as the child. Contact tracing continues, but there is currently no evidence of person-to-person spread of H5N1 bird flu from this child to others. To date, there has been no person-to-person spread identified associated with any of the H5N1 bird flu cases reported in the United States.

This case was detected through influenza testing and reported to CDPH through influenza surveillance. This is the second U.S. case identified through national surveillance. CDC continues to closely monitor available data from influenza surveillance systems, particularly in states affected by outbreaks in animals, including California, where widespread outbreaks of H5N1 bird flu have been detected in wild birds and domestic poultry since 2022 and dairy herds since August 2024 in that state.

Limited and sporadic human infections with avian influenza H5N1 virus, where animal exposure was not identified, are very uncommon but have occurred, primarily in countries other than the United States. These instances underscore the importance of ongoing surveillance and investigations at the local, state, and Federal levels. Including this most recent case, 55 human cases of H5 bird flu have now been reported in the United States during 2024, with 29 in California.

CDC’s risk assessment for the general public is low. However, people with exposure to infected or potentially infected animals, such as birds, dairy cattle, or other animals (including livestock), or to environments contaminated by infected birds or other animals, are at higher risk of infection. CDC recommends avoiding unprotected exposures to sick or dead animals, including wild birds, poultry, other domesticated birds, and other wild or domesticated animals (including cows).

CDC will continue to provide updates as additional information becomes available. For more information, read California’s statement State Reports Single, Possible Case of Bird Flu Virus in Child with Mild Symptoms