As spring brings the return of migrating birds, experts are raising alarms about the spread of bird flu (H5N1) in cats and its potential risk to humans.
A new study from the University of Maryland School of Public Health has reviewed two decades of research on bird flu infections in cats, highlighting the urgent need for better monitoring to prevent the virus from spreading to humans.
The research, published in the journal Open Forum Infectious Diseases, documents 607 cases of bird flu in cats across 18 countries between 2004 and 2024.
Of these infections, 302 led to the cat’s death, and the virus was found in 12 types of cat species, including domestic cats and tigers.
Lead author Dr. Kristen Coleman, an assistant professor at UMD, emphasized that bird flu is highly deadly for cats, yet there is little to no active surveillance.
Most cases are only discovered after the animal has died, making it likely that the real number of infections is much higher.
Coleman pointed out that the virus’s ability to jump between species is especially worrying.
“The virus has evolved, and the way that it jumps between species—from birds to cats, and now between cows and cats, cats and humans—is very concerning,” she said. With summer approaching, researchers expect more cases to emerge on farms and in the wild, increasing the chance for further spread.
The study shows that cats can get bird flu in multiple ways. Some cats contract the virus by eating infected birds or contaminated raw chicken feed, while others pick it up indirectly through other mammals.
For example, farm cats have been infected after being fed raw milk from infected cows, and there have been cases of pet cats spreading the virus to other pets and even tigers spreading it to other tigers.
Infected cats often suffer from severe symptoms like brain swelling, which is sometimes mistaken for rabies.
The most deadly strain of bird flu is responsible for the majority of cases in domestic cats, with a current 90% fatality rate. Despite this high risk, cats are not routinely tested for bird flu, leaving many infections undetected.
Bird flu is also dangerous for humans, although less deadly. Since 2022, the United States has seen 66 confirmed cases in humans and one death. Globally, the virus has killed around half of the 950 people infected.
Although there are currently no confirmed cases of human-to-human transmission, researchers worry that as the virus continues to spread and mutate, it could become more contagious.
Coleman and her team are particularly concerned about the virus spreading in places like animal shelters, which could lead to large outbreaks. This has happened before—back in 2016, a different strain of bird flu swept through shelters in New York City, infecting many animals.
Looking forward, Coleman’s team plans to study how common bird flu and other influenza viruses are in high-risk cat populations, like farm cats. “Our research seeks to protect people and our vulnerable pet cats from the emerging threat of H5N1,” said Ian Gill Bemis, a co-author of the study.
The findings highlight an urgent need for better monitoring of cats for bird flu. Researchers hope that by understanding how the virus spreads among cats, they can prevent it from becoming a larger threat to both animals and humans.
Source: University of Maryland.
