A recent investigation has highlighted a potential case of H5N1, commonly known as bird flu, transmitting from domestic cats to humans for the first time. According to a report published by the U.S. Centres for Disease Control and Prevention (CDC), a veterinary professional in Los Angeles County showed signs of H5N1 infection after interacting with an infected feline.
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The case emerged during a period when 19 pet cats from five different households exhibited severe respiratory, hepatic, or neurological symptoms. Tragically, 14 of these cats died or were euthanised. The findings have prompted health officials to advise pet owners against feeding raw animal products to their cats, as this was determined to be the likely source of infection.
From November 2024 to January 2025, the Los Angeles County Department of Public Health (LACDPH) collected data regarding these feline illnesses. They conducted interviews with cat owners and evaluated staff lists from the ten veterinary clinics that treated the affected animals. Through this review, they identified 139 individuals who may have been exposed to the infected cats.
Of those tested for H5N1, one asymptomatic veterinarian provided crucial evidence of the virus after coming into contact with an affected cat. This individual’s blood serum results indicated an H5N1 infection; however, they remained symptom-free throughout the testing period. Remarkably, a follow-up influenza A test a week later returned a negative result.
The report noted that the cats in question had all ingested commercially available raw milk, raw meat, or raw pet food prior to falling ill. Out of nine tested animals, all were confirmed positive for H5N1 clade 2.3.4.4b, which correlates with the variants responsible for most human infections. Additional cases were detected through various veterinary and laboratory reports, as well as routine testing of brain tissue from euthanised cats.
Health experts have expressed concern over these findings, suggesting that they provide strong evidence of zoonotic transmission—meaning the virus can transfer from animals to humans. In light of this, the CDC has robustly recommended that pet owners refrain from serving raw animal products to their pets. Additionally, it urged veterinary professionals to utilise appropriate personal protective equipment and to follow stringent infection control practices to mitigate potential risks of H5N1 transmission.
Bird flu, a highly pathogenic avian influenza, is caused by a virus that poses a significant threat to birds and can also affect mammals. Among the numerous subtypes of H5 viruses, H5N1 has garnered attention for its outbreaks in the past. Since February 2024, the CDC noted 71 human cases of bird flu in the United States, with two fatalities reported. Most of these cases were linked to close contact with infected birds or animals on poultry and cattle farms.
The emergence of H5N1 in domestic cats, coupled with the documented case of human infection, underscores the necessity for heightened awareness regarding the handling of pets and raw animal products. As researchers and health officials continue to monitor the situation, the focus remains on preventing further transmission and safeguarding both human and animal populations from this infectious disease.
As the CDC emphasises the importance of education about avian influenza and its potential impacts, this case serves as a reminder for pet owners to remain vigilant and informed. With the resurgence of zoonotic diseases, fostering a better understanding of the interplay between animal health and public safety is more crucial than ever.