Avian influenza death of Alaska polar bear is a sign of the virus’ persistence

The highly pathogenic influenza that has already killed vast numbers of birds and numerous mammals continues to circulate in the world’s wild populations

di Yereth Rosen

A polar bear found dead on Alaska’s North Slope is the first of the species known to have been killed by the highly pathogenic avian influenza that is circulating among animal populations around the world.

The polar bear was found dead in October near Utqiagvik, the nation’s northernmost community, the Alaska Department of Environmental Conservation reported.

The discovery of the virus in the animal’s body tissue, a process that required sampling and study by the North Slope Borough Department of Wildlife Management and other agencies, confirmed earlier this month that highly pathogenic avian influenza was the cause of death, said Dr. Bob Gerlach, Alaska’s state veterinarian.
“This is the first polar bear case reported, for anywhere,” Gerlach said. As such, it was reported to the World Organisation for Animal Health and has gotten attention in other Arctic nations that have polar bears, he said.

This was also the first Endangered Species Act-listed animal in Alaska known to fall victim to the disease. Polar bears, dependent on sea ice that is diminishing because of climate change, were listed as threatened in 2008.

While polar bears normally eat seals they hunt from the sea ice, it appears likely that this bear was scavenging on dead birds and ingested the influenza virus that way, Gerlach said. Numerous birds on the North Slope of various species have died from this avian influenza, according to the Department of Environmental Conservation.

However, the bear need not have directly eaten an infected bird to have become sick, Gerlach said.

“If a bird dies of this, especially if it’s kept in a cold environment, the virus can be maintained for a while in the environment,” he said.

The polar bear death is a sign of the unusually persistent and lethal hold that this strain of highly pathogenic avian influenza has on wild animal populations two years after it arrived in North America, officials said.

“What we’re dealing with now is a scenario that we haven’t dealt with in the past. And so there’s no manual,” said Andy Ramey, a U.S. Geological Survey wildlife geneticist and avian influenza expert.

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