Migrating birds bring avian flu to Alaska, present risk to wild flocks
June 28, 2023
Migrating birds have returned to Alaska, and so has the highly pathogenic avian influenza that began to sweep through global bird populations in 2020.
That means Alaskans should continue to be vigilant about the strains that have arrived in the state from across both the Atlantic and Pacific oceans, experts said during a webinar June 6 hosted by the Alaska Native Tribal Health Symposium’s Local Environmental Observer Network.
Alaska’s geographic position, at a point on the globe where different avian flyways converge, makes it a transmission zone for separate strains from both the Eastern and Western Hemispheres.
“Alaska’s in a unique position for a mixing of viruses from Asia and North America,” said January Frost of the U.S. Fish and Wildlife Service.
This influenza wave appears to pose only minute risks to people. So far, there have been only a handful of human cases globally, and those were among people working closely with poultry, said Andy Ramey, a wildlife geneticist and avian influenza expert with the U.S. Geological Survey’s Alaska Science Center.
But for wild birds and other wild animals, it has proved a dangerous illness. Along with the 58 million domestic chickens and other poultry birds lost to the virus in the United States, nearly 7,000 wild birds have died. That is in addition to various mammals like foxes, coyotes, skunks and bears, according to the latest tally.
The effects on wild birds make the outbreak much different from other versions of avian influenza, Ramey and Frost said.
“A few years ago, high-path avian influenza was a poultry disease. And for whatever reason, this high-path avian influenza, these recent strains, have become really well-adapted to wild birds,” Ramey said, referring to high-pathogen viruses. “We’re really in uncharted waters, so to speak.”
In the past, he said, it was assumed that outbreaks would be confined to poultry and would die out there, he said. “I don’t know if that still holds true.”
In Alaska, the documented case count is 232 wild birds, three foxes and two bears as of the first week of June, Ramey said. Those are cases of animals that were found dead or dying, with confirmation in laboratories of highly pathogenic avian influenza infections.
That means the cases represent only a small fraction of the effects in the wild, Ramey said, as most cases likely go unnoticed and unreported by people.
It is common for wild birds to carry numerous influenza viruses, usually of the low-pathogenic variety, according to the USGS. Less common are highly pathogenic viruses, so categorized because they are transmitted easily within domestic poultry flocks; they are of concern because they can kill large amounts of poultry and therefore have significant economic consequences. Until now, highly pathogenic avian influenza viruses have not been much of an issue for the health of wild birds, even though they are carriers and can transmit viruses between continents.
For wild birds, the danger of the current influenza is that vulnerable populations could suffer significant losses. This spring, for example, several California condors were killed by the virus. For a critically endangered population numbering only about 560, the loss of several birds was seen as alarming enough to prompt the U.S. Department of Agriculture to start a flu-vaccination program for the birds.
In Alaska, the birds most commonly found to be victims of this influenza are waterfowl. The top species with documented cases are mallards, bald eagles, ravens, northern pintails, glaucous gulls, American green-winged teals, Canada geese, American wigeons, brant and Sabine’s gulls, Ramey and Frost said in their presentation.
There have been no documented cases of avian influenza in Alaska marine mammals, but there have been elsewhere. For example, avian influenza was linked to a die-off last year of several harbor seals and gray seals in Maine.
The National Marine Fisheries Service is monitoring Alaska marine mammals for signs of influenza, Ramey said.
There are recommended precautions for Alaska bird hunters, even though this virus has rarely been transmitted to people. They should wear protective gear, clean knives and surfaces that come in contact with birds and take other measures, including cooking all meat and eggs to internal temperatures of 165 degrees Fahrenheit.
That last guideline may represent a departure from usual operations in parts of Alaska, Frost said.
“I know it may not be the typical way that people cook their food or eat their eggs, but in order to be as safe as possible, this is what is recommended,” she said.
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