The infected polar bear provides further evidence of the extent of the spread of this virus, a highly pathogenic form of H5N1, and the unprecedented nature of its behavior. Since the virus emerged in 2020, it has spread to every continent except Australia. It has also infected an unusually large number of wild birds and mammalsincluding foxes, skunks, mountain lions and sea lions.

“The number of infected mammals continues to increase,” said Dr. Bob Gerlach, Alaska State Veterinarian.

In most cases, the virus has not caused mass mortality among wild mammal populations. (South American sea lions are one of the notable exception.) But it poses a new threat to the already vulnerable polar bear, threatened by climate change and melting sea ice.

“The problem is that we don’t know the full extent of the possible effects of the virus on polar bear species,” Dr Gerlach said.

The polar bear was found dead last fall in far northern Alaska, near Utqiagvik. Swabs taken from the animal initially tested 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, Dr. Gerlach said.

Last month, tissue samples from the bear tested positive for the virus, according to the Alaska Department of Environmental Conservation. The virus was ultimately identified in multiple organs, Dr. Gerlach said. “I think it would be safe to say he died from the virus,” he said.

Alaska has previously reported infections in a brown bear and a black bear, as well as in several red foxes.

It’s unclear how the polar bear contracted the virus, but sick birds have been reported in the area. The polar bear may have become infected after eating a dead or sick bird, Dr. Gerlach said.

And scientists don’t know if this case is isolated or if other infected polar bears have escaped detection. Monitoring the virus in wildlife populations can be difficult, especially those that live in places as remote as northern Alaska. “How do you know how many are affected? » said Dr. Gerlach. “We really don’t. »

Local scientists, authorities and other experts will continue to look for signs of the virus in wild animals, including polar bears that turn up dead or appear sick, Dr. Gerlach said.

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