A highly lethal form of avian influenza spreading around the world has now been found in a dead polar bear in Alaska. This is the first known case among Arctic animals that are listed as endangered under the Endangered Species Act in the United States, UNN writes, citing The New York Times.
Details
Last fall, a polar bear was found dead in far northern Alaska, near Utqiagvik. Swabs taken from the animal initially came back negative for the virus. But when experts conducted a more comprehensive examination, performing an autopsy and taking tissue samples from the bear, they found clear signs of inflammation and disease, said Alaska State Veterinarian Dr. Bob Gerlach.
According to the Alaska Department of Environmental Conservation, tissue samples from the bear tested positive for the virus last month. According to Dr. Gerlach, the virus was eventually identified in many organs. "I think it would be safe to say he died from the virus," he said.
In Alaska, infections have previously been reported in brown and black bears, as well as several red foxes.
It is unclear how the polar bear contracted the virus, but bird infections have been reported in the area. According to Dr. Gerlach, the polar bear may have become infected after eating a dead or sick bird.
The infected polar bear is further evidence of how widespread the virus, a highly pathogenic form of H5N1, has become. Since the virus emerged in 2020, it has spread to every continent except Australia. It has also infected an unusually wide range of wild birds and mammals, including foxes, skunks, cougars and sea lions.
"The number of mammals with infections continues to rise," Dr. Gerlach said.
For the most part, the virus has not caused massive die-offs of wild mammal populations (South American sea lions were one notable exception.) But they pose a new threat to the already vulnerable polar bear, which is threatened by climate change and melting sea ice.
"The concern is that we don't know the overall magnitude of what the virus could do to polar bear species," Dr. Gerlach said.
And scientists don't know if this is an isolated case or if there are other infected polar bears that have escaped detection. Tracking the virus in wildlife populations, especially in remote places like northern Alaska, can be difficult.
Dr. Gerlach said local scientists, officials and other experts will continue to look for signs of the virus in wildlife, including polar bears that turn up dead or appear sick.
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