Veterinary Professional Contracted Avian Flu from Exposure to Domestic Cat, CDC Reports
A veterinary professional in Los Angeles County showed evidence of highly pathogenic avian influenza A(H5N1) virus infection transmitted through occupational exposure to a sick domestic cat in December 2024, according to CDC’s May 7 Morbidity and Mortality Weekly Report (MMWR). Samples taken from the cat tested positive for the same virus clade that the affected individual had antibodies for. Staff at the clinic where the veterinary professional worked reported no use of personal protective equipment except for gloves during examinations.
The veterinary professional did not report any symptoms of illness, and the infection was identified through serologic analysis of a blood sample. Nonetheless, CDC cautions veterinary professionals to be aware of the risk of influenza A(H5N1) transmission between domestic cats and humans, use appropriate PPE, and follow recommended infection control practices when treating sick animals.
Between November 2024 and January 2025, 19 domestic cats in Los Angeles County became severely ill after consuming commercially purchased raw milk, raw meat, or raw pet food, MMWR explains. Nine of these cats tested positive for avian influenza A(H5N1) clade 2.3.4.4b virus, which has spread widely among wild birds and domestic poultry in the United States and occasionally infected mammals, including dairy cows. A total of 139 people, including pet owners, veterinary staff members, an animal control worker, and a local health department employee, were potentially exposed to cats with suspected or laboratory-confirmed influenza A(H5N1) infections. Thirty people reported flu-like symptoms to the Los Angeles County Department of Public Health, and 33 people provided nasopharyngeal swabs. None tested positive for influenza A(H5N1), although 12 tested positive for seasonal influenza A(H3N2), rhinovirus, and an endemic coronavirus.
In April 2025, 25 of the exposed people agreed to participate in a serologic survey for evidence of influenza A(H5N1) infection. Participants completed a questionnaire seeking information on potential risk factors and submitted blood samples for serologic analysis. Only the single sample submitted by the asymptomatic veterinary professional tested positive for antibodies against influenza A(H5N1).
The MMWR notes that RT-PCR and serologic testing were not performed for all exposed individuals, so some infections may have been missed. CDC advises members of the public not to feed their cats raw milk, raw meat, or raw pet food, as cats that eat or drink these products may be at risk for infection.
More information is available in the MMWR.