A Centers for Disease Control and Prevention (CDC) report has revealed that cats infected with bird flu may have spread the virus to humans, and vice versa, in the same household. The data, which appeared briefly online but then vanished, includes crucial information about the risks of bird flu to people and pets.
According to a copy of the data table obtained by The New York Times, an infected cat may have spread the virus to another cat and to a human adolescent, causing severe symptoms that led to the cat’s death four days after infection. In another household, a dairy farmworker showed initial symptoms, followed by a cat becoming ill two days later, resulting in the cat’s death on the third day.
The H5N1 virus, primarily adapted to birds, has been circulating in dairy cattle since early last year and has infected at least 67 Americans, with only one fatality reported. Experts say that the finding is not entirely unexpected but are alarmed by its delayed release.
“The finding that cats might have passed the virus to people was not entirely unexpected,” said Jennifer Nuzzo, director of the Pandemic Center at Brown University. “But it’s alarming that the finding had not yet been released to the public.”
The CDC has announced its intention to publish the full data and context for other scientists to review. This revelation comes as experts highlight the need to understand the potential risk of bird flu transmission from cats to humans, given the high number of domestic cats in the US and their close contact with people.
Historically, H5N1 primarily affected birds, but new versions of the virus have shown capacity to infect mammals, including wild and domestic cats, seals, and dairy cows. Infections in mammals provide opportunities for the virus to evolve, potentially increasing its ability to infect humans more easily.
Source: https://www.nytimes.com/2025/02/06/health/cdc-bird-flu-cats-people.html