CDC confirms cat-to-human H5N1 case

The U.S. Centers for Disease Control and Prevention said this month that it found serologic evidence of H5N1 infection in a veterinary professional who had been exposed to infected domestic cats in Los Angeles County. The finding appeared in a May 7 report in the CDC’s Morbidity and Mortality Weekly Report and was described by the agency as possible cat-to-human transmission of highly pathogenic avian influenza A(H5N1). The exposed worker was asymptomatic, according to the report. The cats in the cluster became ill after consuming commercially purchased raw milk, raw meat or raw pet food. ### How did the CDC link this case to infected cats? The CDC said 19 domestic cats in Los Angeles County became ill between November 2024 and January 2025 after consuming raw animal products, and nine tested positive for H5N1 virus. Public health officials monitored 139 people who had been exposed to the cats. Thirty reported influenza-like symptoms, but none had a positive H5 PCR test at the time, the report said. (cdc.gov) In April 2025, the Los Angeles County Department of Public Health and the CDC invited exposed people to join a serosurvey. The agency said blood samples from 25 people were tested, and one veterinary professional had antibodies specific to the H5N1 clade linked to the infected cats. The worker reported no other known risk factors for H5N1 infection, according to the CDC. (cdc.gov) ### What exactly did the CDC say about transmission? The CDC said the findings were “serologic evidence of possible transmission” from a domestic cat to a human, rather than a definitive proof based on a positive clinical test during illness. The agency said the worker had no symptoms and did not report influenza-like illness after the exposure. The May 7 report said the veterinary professional did not use respiratory or eye protection during the exposure. (cdc.gov) The CDC said that detail underscored the importance of infection-control practices in veterinary settings when staff handle cats suspected or confirmed to be infected with H5N1. ### Why were raw animal products part of the investigation? The CDC report said the infected cats had consumed commercially purchased raw milk, raw meat or raw pet food before becoming ill. (cdc.gov) A separate CDC publication on bird flu in pets advises owners not to feed raw animal products to cats, and the agency’s recent report repeated that warning in its public health implications section. (cdc.gov) Minnesota health guidance for pet owners and veterinary clinics also says infected animals can expose people through saliva, feces, milk and other body fluids, and that veterinary staff working in close contact with suspected or confirmed infected companion animals should use infection-control precautions. ### What does this change for veterinarians and pet owners? (cdc.gov) The CDC says the current public health risk from H5 bird flu remains low, even as it continues to track sporadic human cases tied to animal exposure in the United States. But the agency separately advises veterinarians and veterinary staff to avoid direct contact with infected cats without personal protective equipment, including precautions for respiratory and eye exposure. (health.state.mn.us) The CDC also said people who handle sick or infected animals face greater risk than the general public. Its guidance for cats and other exposed animals remains in place, including recommendations for veterinarians, staff and caretakers working in field and clinical settings. ### Where can readers find the official record? The CDC published the case details in Volume 75, Issue 17 of MMWR on May 7, 2026, under the title “Serologic Evidence of Highly Pathogenic Avian Influenza A(H5N1) Virus Transmission to a Veterinary Professional.” The agency also maintains separate guidance pages on bird flu in pets, current H5 bird flu conditions, and precautions for veterinarians and animal caretakers handling suspected or confirmed infected cats. (cdc.gov 1) (cdc.gov 2) (cdc.gov 3)