Avian influenza first appeared in Alaska in 2022, and it was rough: the virus claimed the life of a brown bear cub at a state recreation site on Kodiak. A second bear cub in Southeast Alaska was also infected. In 2022 the virus killed more than 1,000 domestic poultry in the Matanuska-Susitna Valley and it slowed shipments of eggs from Washington state. Now, scientists are trying to figure out how the bird flu fared in Alaska over the winter.
“People have understood that avian influenza viruses can remain viable or infectious in cold water for long periods of time for many years now,” said Andy Ramey.
Ramey, a research geneticist with the U.S. Geological Survey Alaska Science Center and the director for the Molecular Ecology Laboratory, wants to find out more about how the virus overwinters.
“In Minnesota and Alaska, in our initial experiments, we found that viruses seem to remain infectious for more than seven months,” Ramey said.
In those experiments, birds were exposed to infected water samples that were kept cold in a lab. Scientists also tested the virus in the field to find out more about the effects of cold winter temperatures. “In another experiment conducted only in Alaska,” said Ramey, “we left some of these vials in wetlands for more than a year. And a year later, some small proportion of the viruses were still viable.”
Federal datashows a total of 232 recorded cases among wild birds in Alaska since April 2022. So far this spring, at least one wild bird on the Yukon-Kuskokwim (Y-K) Delta was found dead from the virus. Hunters who have been out along Alaska’s west coast and further inland on the Y-K Delta this season say that they haven’t seen anything out of the ordinary.
In recent months, the U.S. Department of Agriculture has reported fewer avian influenza infections among wild birds across North America compared to the same time period last year. Ramey said that could be tied to an increase in immunity among wild birds, but he said that vigilance is key and that anyone who notices a sick or dead wild bird should still report it.
“We're in some ways in some uncharted water here. Historically this didn't happen: we didn't have highly pathogenic viruses in wild birds. So our experience in this scenario is pretty limited,” Ramey said.
According to Ramey, scientists started looking for avian influenza in North America in the 1990s, but it didn’t show up on the continent until 2014. The virus persisted for two years and appeared again in 2021.
“Since late 2021, we've had roughly 3,000 detections in wild birds in the United States,” Ramey said. “So this is like nothing we've ever seen. And now in this current outbreak, we're seeing numerous, I'd say many wild birds die on account of highly pathogenic avian influenza infection.”
Ramey likened the outbreak to the wildlife equivalent of the coronavirus pandemic humans have endured for the last three years.
