Scientists found fewer positive cases of bird flu in Alaska this year
With migratory bird season coming to a close, state and federal officials are reporting that the number of bird flu cases, particularly the highly pathogenic kind, are continuing to trend downwards, though they’re still waiting to test some samples.
It took about three months to get test results back from the migratory bird that was found dead in Western Alaska on Thursday, May 25. Yukon Delta National Wildlife Refuge scientists suspected the dead cackling goose to be the first casualty caused by the highly pathogenic avian influenza. But State Veterinarian Dr. Robert Gerlach said that the goose didn’t test positive for bird flu.
“Yeah, that was a negative for the high pathogen influenza. I don't believe that it even had a low pathogen strain there,” Gerlach said.
According to the Centers for Disease Control and Prevention (CDC), avian influenza viruses are found among bird populations worldwide and spread via inhalation, ingestion of infected secretions, and through contact with contaminated material from infected birds. Avian influenza virus strains are classified according to the severity of illness they cause in domestic poultry. Low pathogenic avian influenza typically causes few or no symptoms in poultry, while highly pathogenic avian influenza can cause severe illness and death. Avian influenza viruses rarely infect humans, according to the CDC.
Gerlach said that flu testing for wild birds takes time. There can be a delay in reporting the results from a bird that was found or sampled in remote parts of Alaska. If a sample or the entire bird is collected, it is first shipped to a state lab in Anchorage. They have to thaw it out and then process it.
“Once we get a sample or if we receive a swab sample from the remote area of the state, we send it down to a laboratory in Washington state or the Washington State Animal Diagnostic Laboratory. It takes them generally two days to go ahead and receive the sample, and then process it and tell us whether it's a avian influenza infection that's going on,” Gerlach said.
Generally that lab doesn’t identify which strain of the influenza it is, so the sample must be sent to another lab.
“They then forward that down to the [United States Department of Agriculture] office or laboratory in Ames, Iowa for further testing. That's the laboratory that goes ahead and then will give us whether there's a high pathogen strain,” Gerlach said. “Then we'll work on the genetic strain of the virus to identify whether it's a North American strain, or whether it's a new introduction, or whether it's a there's any changes or mutations that are going on in the virus.”
But it’s a faster process for domestic birds. Gerlach credits this to the better ability to control the domestic bird population. Once scientists identify high pathogen influenza, they need to move quickly to quarantine the flock and kill the birds.
“As soon as we identify it's a positive for high pathogen avian influenza, then we go in and depopulate the flock to prevent that from spreading to other birds or to wild birds. And so we have a much higher priority to go ahead and process those samples,” Gerlach said.
Recently, a glaucous gull did come back positive, making it the first confirmed positive case in the Yukon-Kuskokwim Delta. Gerlach also said that the U.S. Fish and Wildlife Service found some dead murres from a mortality event in the Bethel census area. That agency confirmed 20 positive cases from dead common murres on Sept 15.
“A large number of birds died, and we've identified an influenza virus, and we sure don't know what that virus is yet. I'm making an assumption that it's more than likely going to be a high pathogen influenza virus, but we'll go ahead and hopefully find out because oftentimes, as we see, we've had other mortality events occur across the state. Large number of birds die, they send them into us,” Gerlach said.
But this shouldn’t be alarming. Overall, Gerlach said that they saw a decreasing number of cases this year. According to a State of Alaska Epidemiology Bulletin, in 2022 there were 123 positive cases from the 850 samples submitted to the state lab. That is just 14% of the samples tested from both wild and domestic birds from across the state.
Currently, Gerlach said that the most prevalent strain of the highly pathogenic virus in North America is known as H5N1. And, although H5N1 primarily affects birds, in Alaska it has been detected in a brown bear in Kodiak, a black bear in Glacier Bay National Park, and three red foxes: one in Nome, one in the Matanuska-Susitna Valley, and one in the Aleutians.