Janet Loehrke,Karen WeintraubUSA TODAY
Researchers are concerned that the more the bird flu virus – also known as avian influenza H5N1 – spreads among animals, the higher the risk it will jump to people.
The virus has been found throughout Europe, the Middle East, Southeast Asia, several areas in Africa and, most recently, the U.S. This strain of bird flu has been documented since at least the 1990s. A few years ago, however, it underwent a mutation that made it more contagious among a wider range of bird species as well as mammals.
The outbreak is concerning because of the virus' ability to infect other animals, such as cattle. In a recent study, the data shows that the virus can jump back and forth between birds and cows, which may help it spread over large geographic areas.
Here's what we know about the spread of the bird flu virus in the U.S.:
Bird flu virus outbreak in dairy cows
The multi-state outbreak, the first ever seen in cattle, probably began late last year.
The Centers for Disease Control and Prevention and the U.S. Department of Agriculture have confirmed the safety of milk and milk products after more than 42 dairy cattle herds (as of May 10) in nine states and one man have been confirmed infected in the U.S. since late March.
According to the health officials, meat samples from retail locations in states where dairy cows are experiencing avian flu outbreaks are being tested to confirm that raw meat poses no health risk to the public.
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Pasteurized dairy is safe
In April, the U.S. Food and Drug Administration said fragments of thevirus were found in samples of pasteurized milk.
Cattle apparently can spread H5N1 through their milk. It's not clear whether they can pass it through other routes, but researchers are studying this now.
Later studies confirmed that pasteurization, the process of heating milk to kill pathogens, destroys the H5N1 virus.
So the fragments seen in the milk were not contagious and the milk supply and products made from pasteurized milk are safe, the FDA's Dr. Donald A. Prater said earlier this month. Tests of infant and toddler formula did not find any viral fragments, so these are also safe, he said.
Bird flu's adaptability to spread
There have been two human cases of bird flu in the U.S.: in 2022 (in a case not connected to the current outbreak) and April of this year. Each case involved people who work with animals. The more times humans are exposed to the virus, the higher the likelihood that it may mutate to become transmissible among people, leading to an outbreak or even a wider pandemic.
Human cases of avian flu are still very rare, but when they do occur, they can be fatal. There have been reports of 889 cases and 463 influenza-related deaths from 23 different countries worldwide from 2003 and April 1, 2024.
There have been reports of wild bird-to-cow, cow-to-cow, cow-to-poultry, and two cases of cow-to-human transmission. There is no evidence so far of human-to-human transmission.
More: Bird flu outbreak: Don't drink that raw milk, no matter what social media tells you
Where bird flu has been detected in wild animals
Since 2022, several U.S. counties have reported that wild animal species have become infected with the bird flu virus.
The virus has been found in more than 20 wild mammal species, including geese, raccoons, mountain lions and a zoo tiger.
The disease isn't limited to land-dwelling mammals.
According to a study released in April, a dolphin in Florida died in 2022 from bird flu. It is the first case of highly infectious avian influenza in North America to be reported in a cetacean.
More: Four reasons to be concerned (but not freak out) about the bird flu
Can dogs and cats get bird flu? The short answer: Yes.
Cats are particularly vulnerable because they typically interact with wild birds. In April, three cats were found dead on a Texas dairy farm after drinking unpasteurized milk from infected cows. In 2016, a cat spread the virus to a person in New York City, according to the CDC.
You may want to avoid taking your dog on walks in places that are close to where there are a lot of wild birds or bird droppings, such as lakes or ponds. It's best to limit your pet's exposure to wildlife that may be infected.
What are symptoms to look for in your dog or cat?
- Fever
- Lack of energy
- Red eyes
- Head tilt
- Shortness of breath
SOURCE Reuters, Centers for Disease Control and Prevention, U.S. Department of Agriculture, Nature.com and Harvard Medical School, American Veterinary Medical Association and USA TODAY research
CONTRIBUTING Julia Gomez and Mike Snider
