Three grizzly bears that were behaving oddly subsequently tested positive for a strain of bird flu, according to a January 17 statement from Montana Fish, Wildlife and Parks (FWP).
The bears appeared to suffer from neurological issues, displaying symptoms like partial blindness and disorientation.
The neurologically impaired young bears were all discovered in different locations. Due to the severity of their symptoms, the animals had to be euthanized.
Typically, highly pathogenic avian influenza (HPAI), a strain of bird flu, is limited to birds, as implied by the name. These discoveries, however, which occurred in the fall of 2022, were the first time the disease has been identified in grizzlies.
Roughly 58 million poultry have been affected by the bird flu. The majority, 40 million, were egg-laying hens. As a result of the substantial culling needed to control the flu’s spread, the cost of eggs has skyrocketed in North Texas and elsewhere in the country, as reported by The Dallas Express.
The discovery in Montana comes amid one of the worst avian flu outbreaks in history, which began in February 2022. Texas identified its first cases roughly two months later, in April, The Dallas Express reported.
Avian influenza is classified as either “low pathogenic” or “highly pathogenic.” The low variation manifests into mild symptoms among birds. The highly pathogenic variant, however, can spread quickly and has a substantially higher death rate.
In mammals, avian flu can lead to exhaustion or neurological disorders like seizures. While this is the first instance of witnessing grizzlies with the condition, the virus was previously identified in a black bear cub last year in Alaska. As in Montana, the black bear cub suffered from neurological problems and had to be euthanized.
“It was very sad to see the animal (was) not going to recover. Its brain was swollen, and it would have died, probably within hours, had it not been euthanized,” said Kimberlee Beckmen, a wildlife veterinarian for Alaska’s Department of Fish and Game, speaking to Alaska Public Media in November 2022.
Other animal species have similarly tested positive for the virus. Across the United States and beyond, raccoons, rodents, foxes, skunks, ferrets, horses, coyotes, pigs, tigers, cats, and dogs have all been infected.
According to Jennifer Ramsey, Montana FWP Wildlife Veterinarian, these mammals likely contracted the disease after eating infected birds.
On rare occasions, bird flu can even be transmitted to humans. Symptoms include nausea, abdominal pain, fever, coughing, diarrhea, vomiting, eye infections, and difficulty breathing.
According to the World Organization for Animal Health, individuals working closely with infected birds or among contaminated environments face the highest risk. Still, only a single case of human infection was reported in the United States as of April 2022, according to the CDC.