Bird Flu Cases May be Spreading From Cat Owners to Their Pets

Internal emails reveal Michigan health officials suspected that owners may have inadvertently spread bird flu to their household cats, raising new concerns about transmission patterns of the virus.

“If we only could have gotten testing on the [REDACTED] household members, their clothing if possible, and their workplaces, we may have been able to prove human-to-cat transmission,” officials wrote in a July 22 email obtained by KFF Health News.

Another email urged publishing a report “to inform others about the potential for indirect transmission to companion animals.”

The emails were obtained via record requests and document the ongoing struggle to track cases of the H5N1 virus in cats. They suggest that domestic cats may become infected from droplets known as fomites on their owners’ persons.

These communications mark the latest in a slew of recent cat-related infections across the U.S., most notably in Colorado, where six cats have tested positive for H5N1 in 2024. Two of these cases occurred in indoor-only cats with no direct exposure to infected animals.

The Colorado infections were confirmed by the Colorado Veterinary Medical Association (CVMA) in an update posted on its website in August.

“One of these cases was directly associated with a known infected commercial dairy facility,” the update said. “Two of the six cases were indoor only cats with no direct exposures to the virus. Three of the six cases were known indoor/outdoor cats that hunted mice and/or small birds as prey and also spent time indoors with their owners.”

The spread of bird flu to household pets marks a significant development in an outbreak that has primarily affected poultry and cattle.

A map posted on the U.S. Department of Agriculture (USDA) website, last updated on October 29, reveals domestic cats have been infected far and wide, including in Texas, Oregon, Ohio, Minnesota, Montana and Idaho.

“There have been 53 detections in domestic cats since the onset of the 2022 outbreak,” Will Clement, senior advisor for strategic communications at the USDA, told Newsweek.

Clement explained that other than the two indoor-only cats, the rest were outdoor cats close to infected premises or stray cats on farms.

Kristen Coleman, an assistant professor at the University of Maryland School of Public Health, has documented a “drastic rise” in feline infections beginning in 2023, coinciding with the rapid spread of the current H5N1 strain among mammals.

“As companion animals, domestic cats provide a potential pathway for avian influenza viruses to spillover into humans,” Coleman said in a June statement coinciding with a study she authored on the spread of bird flu in cats.

“We looked at the global distribution and spread of bird flu infections in feline species between 2004 and 2024 and found a drastic rise in reports of feline infections starting in 2023, with a spike in infections reported among domestic cats, as opposed to wild or zoo-kept animals. This increase coincides with the rapid spread of the current strain of H5N1 among mammals.”

Coleman advised owners not to feed their cats raw meat or dairy and to limit unsupervised time outdoors in order to prevent infection. Cats may exhibit respiratory symptoms, such as difficulty breathing, and in some cases can go blind as a consequence of bird flu.

On its website, the Centers for Disease Control and Prevention acknowledged cats’ susceptibility to bird flu, while maintaining that the risk to the general public remains low.

The agency’s website noted that domestic animals can become infected if they “eat or be exposed to sick or dead birds infected with bird flu viruses, or an environment contaminated with bird flu virus.”

As health officials continue monitoring the situation, the Michigan emails highlight the challenges in tracking and preventing transmission through indirect routes.

“The virus is going to sneak up in more places, just like it did in dairy farms,” Coleman said. “We know cats are being infected, so let’s get ahead of it.”

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Update 11/5/24 6:11 a.m. ET: The article was updated with comments from Will Clement.