August 19, 2024
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Bird flu infects pet cats: what you need to know
As bird flu spreads to animals such as cats and cows, it has more opportunities to adapt and become more susceptible to human infection.
For two and a half years, a deadly strain of avian influenza called H5N1 has been ravaging chicken farms. More than 100 million birds have been killed in the United States due to the disease and attempts to contain its spread. Wild birds have also died in large numbers. In late March, scientists confirmed that H5N1 was sickening cows on U.S. dairy farms. As of August 15, about 200 cows in 13 states were infected. Confirmed cases of human infection are far fewer, with only 13 reported cases between April and August 9, most of which were mild, characterized by conjunctivitis. However, it is possible that human infections are being missed.
The virus has now been found in indoor cats. On August 9, the Colorado Department of Public Health announced that six cats in the state have been confirmed to be infected this year, two of which were found in samples taken in May, while at least three were found in samples taken in July. What’s particularly worrying about this announcement is that two of the infected cats are indoor animals. Scientists say this is a sign that the virus is spreading among animals and is slowly impacting the daily lives of average Americans.
“The identification of H5N1 in indoor cats is a major concern,” said Megan Davis, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health. “Increased surveillance, understanding the spread of this virus, and better messaging are things we need to do right now.”
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This isn’t the first time that cats have been infected with the strain of avian flu found in dairy cows: At least 36 house cats have been reported infected across the country since March, including in hard-hit states Texas and Michigan. But some of the cats may have lived on dairy farms, where they may have roamed among infected cows and drunk virus-laden milk. Outdoor cats can also become infected from birds and other small animals they eat.
Few details are known about the new cases, and it’s possible that indoor cats may have spent time outdoors or eaten raw milk or meat from infected animals. But if that’s not the case, the possibilities are worrying. These cats could have contracted the virus from infected rodents in the home, or they could have picked up the virus from an unknown, asymptomatic carrier through contact with other animals. Either scenario suggests that avian flu is more persistent than we realize.
In Colorado, the disease seems especially prevalent: More than 8 million commercial chickens have died from the outbreak so far, there have been confirmed cases of avian flu in more than 60 dairy herds, and there have been 10 human infections. But epidemiologists say that doesn’t necessarily mean Colorado is a hotspot for the virus any more than other states. “They’re really taking it seriously, and I think it’s highlighting to everyone else how much we’re missing,” says Seema Lakdawala, a molecular virologist at Emory University. “It’s not like, ‘Everybody’s looking for it, and we’re only finding it here.’ It’s more like, ‘If you look, you’ll find it.'”
So scientists aren’t just concerned about what’s happening in Colorado; do not have Avian flu is “probably more widespread than we realize, and not just in areas where there are concentrations of livestock or where (cases) have been reported,” says Michelle Baron, an epidemiologist at the University of Colorado Denver.
The first concern is the sheer amount of avian flu virus in the environment, but the second is the number and types of animals it continues to infect unchecked. New infections provide an opportunity for dairy strains of avian flu virus to meet and mix with other flu viruses present in the new host. “Influenza viruses are notorious for mutating and taking genes from other viruses,” Baron says. “At what point does the virus change enough to risk making people seriously ill?”
Davis said pets are a particularly difficult population for epidemiologists to track because there are no state or federal regulatory agencies to monitor their health like there are for humans and livestock, and veterinary care can be expensive for owners to afford.
Pet owners who are worried about bird flu should be aware of potential ways their pets can become infected, Davis says. Don’t feed your pet raw milk or raw foods, whether commercially bought or prepared at home. (Humans should also take raw milk, eggs and meat off their menus. Pasteurization has been proven to kill viruses in milk, and cooking food kills most pathogens.) Outdoor cats are at risk, especially if they may be hunting infected animals when unsupervised. There have been no reports of pet dogs contracting bird flu, but Davis warns that dogs that may come into contact with waterfowl may be at higher risk of contracting the H5N1 strain. Keep an eye out for behavioral changes that may indicate your pet may be sick, such as loss of appetite or difficulty breathing, and consult a veterinarian if you’re worried. People who keep pet ferrets should also be especially careful, as these animals are highly susceptible to influenza viruses and can develop serious infections.
Experts say the U.S. government and society at large need to take avian flu seriously. “I think we’re at a turning point in this epidemic,” Lakdawala said. She would like to see the federal government encourage state agencies to work together to increase surveillance and curb animal-to-human transmission — efforts that have so far been largely the responsibility of state governments.
Baron is particularly concerned that the emotional toll of the COVID-19 pandemic is preventing a strong response to avian flu. “I want people to understand that testing is a good thing, knowledge is a good thing,” he says. He worries that the trauma and politicization of the pandemic are still raw in people’s minds, and that a desire to avoid a repeat of that experience is preventing people from confronting the threat of avian flu.
For now, the Centers for Disease Control and Prevention emphasizes that for most people, except those who have had direct contact with infected animals, the threat from bird flu is very small for now. But that could well change if the virus rages unchecked. If bird flu were becoming more dangerous, a big sign would be a spike in infections among people who have no connection to sick animals. That would suggest the virus could be transmitted directly from person to person. “Given how many viruses there are in nature right now, I don’t think it’s that far off to actually see that,” Lakdawala says.
The risk is compounded by the fact that the regular flu season is just a few months away. There is no evidence that annual vaccines for seasonal influenza viruses can prevent avian flu, Davis points out. And if you get both avian and seasonal flu at the same time, the worst parts of each virus could combine into a nightmare pathogen. “The worst case scenario is that it becomes very contagious and very severe, not just in humans but in animals,” Davis says. The CDC has begun an effort to vaccinate farmworkers against seasonal flu to reduce the chances of this happening, but a vaccine tailored to avian flu has not yet been approved for distribution.
Even taking into account the lack of monitoring, the three scientists stressed that the dire scenario they professionally worry about is not yet inevitable. “We have an opportunity now to work hard in advance to avoid getting into a situation where we have to shut down[society]again,” Lakdawala said. “Nobody wants an H5 pandemic. Nobody.”
