CDC confirms cat-to-human H5N1

The Centers for Disease Control and Prevention said on May 7 that it had found evidence of H5N1 transmission from a domestic cat to a human in Los Angeles County, California. The finding came from a CDC and Los Angeles County Department of Public Health investigation into 19 pet cats that became ill between November 2024 and January 2025 after consuming commercially purchased raw milk, raw meat or raw pet food. Among 139 people identified as exposed to those cats, one asymptomatic veterinary professional later showed antibodies consistent with H5N1 infection. CDC said the current public health risk from H5 bird flu remains low and that there is no known person-to-person spread at this time. ### How did investigators link the infection to a cat? The CDC said the evidence came from a serosurvey offered in April 2025 to people who had been exposed to infected cats. Of 25 people who volunteered for testing, one veterinary professional had serologic evidence of H5N1 infection after occupational exposure to an infected domestic cat, according to the agency’s Morbidity and Mortality Weekly Report. (cdc.gov) Los Angeles County investigators said the worker did not report flu-like illness after the exposure and had no other known risk factors for infection. The cat linked to that exposure had been treated at four veterinary practices before a positive feline respiratory panel result was available, and the worker had not been wearing personal protective equipment over the mouth or eyes during the exposure, trade publication dvm360 reported, citing the investigation. (cdc.gov) ### What happened in the broader cluster of sick cats? Nineteen domestic cats in Los Angeles County became sick after consuming commercially purchased raw animal products during the November 2024 to January 2025 period, the CDC said. Nine of those cats tested positive for H5N1 clade 2.3.4.4b, genotype B3.13, while the remaining cases were identified through veterinarian reports, commercial laboratory reports or routine RT-PCR testing of brain tissue from euthanized cats. (dvm360.com) The Los Angeles County Department of Public Health interviewed 139 exposed people, including 11 pet owners in five households, 126 people from 10 veterinary practices, one person from an animal control agency and one from a local health department, according to the investigation. Thirty people reported influenza-like symptoms during initial monitoring, but none had a positive H5 RT-PCR result. (cdc.gov) ### Why are health officials focusing on raw pet food and raw milk? The CDC said the infected cats had consumed commercially purchased raw milk, raw meat or raw pet food before becoming ill. In its public health guidance, the agency advises pet owners not to feed raw animal products to cats. The American Veterinary Medical Association said the Los Angeles County investigation documented a domestic cat transmitting H5N1 to a veterinary professional and repeated the CDC recommendation on raw animal products. (avma.org) CDC also says people exposed to infected cats or other animals should be monitored for respiratory symptoms or conjunctivitis for 10 days after their last exposure. (cdc.gov) ### Does this mean H5N1 is spreading between people? CDC’s current H5 bird flu situation page says there is no known person-to-person spread at this time. The agency says H5N1 is widespread in wild birds and has caused outbreaks in poultry and U.S. dairy cows, with sporadic human cases, but it continues to assess the public health risk as low. The May 7 report was narrower than that broader national assessment. (avma.org) It documented zoonotic transmission from a domestic cat to a human, not sustained transmission among people, and it identified the infected person through antibody testing rather than a positive diagnostic test during acute illness. ### What changes are officials asking for now? CDC said veterinary professionals should be aware of H5N1 infection risks, use appropriate personal protective equipment and follow infection-control practices to reduce zoonotic transmission. (cdc.gov) The agency’s guidance for animal-care settings says people with close or prolonged unprotected contact with infected cats or contaminated environments are at greater risk of infection. (cdc.gov) As of March 6, 2026, CDC said it would continue reporting additional human H5 bird flu cases through its situation updates and FluView. Los Angeles County and CDC used the April 2025 serosurvey to identify the cat-linked infection, and the MMWR report published on May 7 sets out the exposure counts, testing results and prevention recommendations that veterinarians and pet owners are now being asked to follow. (cdc.gov 1) (cdc.gov 2)