Deadly strain hits about 40 birds at Big Twin Lake
An extremely virulent strain of avian influenza that’s been sickening and killing waterfowl and raptors across the country is believed to be the cause of death of some 40 birds at Big Twin Lake.
The birds that died on Big Twin Lake were mostly Goldeneye and Bufflehead ducks, Washington Department of Fish and Wildlife (WDFW) Communications Manager Staci Lehman said. The deaths seem to have occurred in late December and early January, but because it wasn’t safe to collect the birds in a timely manner, they weren’t tested for avian flu, WDFW wildlife veterinarian Katherine Haman told the Methow Valley News.
Nevertheless, the deaths were very consistent with what biologists expect from avian influenza, WDFW Okanogan District Wildlife Biologist Scott Fitkin said.
Methow Wildlife Area staff were able to remove and safely dispose of about two-thirds of the carcasses, but the others were still frozen in the ice and not safely retrievable, Lehman said. The birds were safely disposed of in a landfill, Fitkin said.
WDFW had been seeing about two cases of bird flu a week, but that grew to five to 10 cases in the late fall and early winter.
Avian flu is classified in two categories, low- and high-pathogenic. Low-pathogenic viruses cause either no symptoms or just mild disease, while highly pathogenic avian influenza (HPAI) can rapidly sicken and kill wild and domestic birds, WDFW said. This strain of HPAI has been confirmed in wild birds and backyard flocks in Washington since spring 2022.
The virus lives for at least two weeks in bird droppings and can survive freezing temperatures. Because it persists less well in hot weather, WSDA had hoped that the summer heat would help control the spread.
However, since this avian flu strain is especially deadly to waterfowl and raptors, particularly scavengers, the birds often die within a couple of days and it’s common not to see symptoms, Haman said. The current outbreak is very different from anything they’ve seen circulating in wild birds and there’s still a lot biologists don’t know about it, she said.
Birds that don’t die right away exhibit neurological symptoms and often can’t stand or fly, or their head may be twisted around, Haman said. Birds may have a discharge from the nose and eyes. Another indication of infection is when birds — especially wild birds — are completely unafraid of humans, Washington State Department of Agriculture (WSDA) Media Relations Coordinator Amber Betts said.
Because waterfowl tend to forage on the ground or in shallow water and stand in their own droppings, the virus spreads easily, Haman said.
Biologists believe waterfowl are a natural host for avian flu, and in most years, birds get mild cold symptoms and then recover and develop immunity, Haman said. Young birds that haven’t developed immunity are usually the ones that show signs of illness, she said.
In the current outbreak, raptors — particularly scavengers that eat sick or dead birds — are suffering the biggest impact, Haman said. Biologists don’t know if raptors also develop an immunity to the disease. Songbirds don’t appear to be affected by the flu.
Report sick birds; get more infoReport sick or dead birds or wildlife at wdfw.wa.gov/sickwildlife. Although the agency doesn’t respond to all reports, they log all of them and continue to sample a subset.
People with questions about bird flu or who find multiple dead birds, should call WSDA at 1-800-606-3056.
WDFW and WSDA both provide information on bird flu. Check wdfw.wa.gov/species-habitats/diseases/bird-flu and agr.wa.gov/birdflu.
This virulent avian flu has been raging across the world. It circulated in Europe in 2021 and 2022 and was first confirmed in North America in a bald eagle in Vancouver, British Columbia in March 2022, according to WDFW. WDFW tested 700 wild birds in 2021 and 2022 and found no cases of the highly pathogenic strain in Washington until spring 2022.
But in just over a year, since last January, more than 58.3 million wild, commercial and backyard birds in 47 states had been sickened, died, or been culled because of avian flu, according to the federal Centers for Disease Control and Prevention (CDC).
The largest outbreaks in Washington have been in areas with a lot of waterfowl, such as on the Columbia River and in Skagit, Whatcom and Snohomish counties, although there have been reports in every county, Haman said.
HPAI was confirmed in a mixed backyard flock in Okanogan County last May, just a week after the first Washington cases were detected in Pacific County.
Although none of the strains currently circulating has been identified as of high risk to humans, people have gotten sick from other strains of avian flu, generally after prolonged contact with birds. Nevertheless, it’s a public health concern, Haman said.
Initially, the state tested all dead wild birds, but, at $120 per sample, WDFW doesn’t have the funds to test every suspected case. WDFW is prioritizing testing for suspected cases in new geographic areas, new bird species, endangered species, large mortality events of more than 50 birds, and mammals, Haman said.
Bird flu in mammals
WDFW and wildlife agencies in other states have been finding mammals infected with the avian flu. In Washington, cases have been confirmed in three raccoons and one bobcat, Haman said. Still, cases in mammals are quite rare, Fitkin said.
Montana Fish, Wildlife & Parks (FWP) announced that three juvenile grizzly bears had tested positive for HPAI after necropsies in January.
The bears, in a several-hundred-mile area, were euthanized in the fall when they were found with partial blindness, disorientation and other neurological issues. This was the first documented instances of HPAI in grizzlies. “We suspect these mammals probably get the virus from consuming infected birds,” FWP Wildlife Veterinarian Jennifer Ramsey said.
Domestic dogs and cats could get sick from eating a sick bird or carcass and would probably develop symptoms of incoordination, Haman said. The disease is most likely treatable with medication from a veterinarian.
It’s unlikely that people would get sick through direct contact with an infected pet, according to the CDC. Several years ago, a veterinarian exposed to a cat infected with bird flu developed mild flu symptoms, according to the CDC. Last year, a person involved in culling poultry suspected of having bird flu developed fatigue for several days and recovered, the CDC said.
People with flu symptoms who may have been exposed to a sick bird or other animal should contact their health care provider.
Hunters who use dogs to retrieve waterfowl should be careful to keep the dog from eating the bird. Otherwise, the risk is believed to be low, Haman said.
Hunters should wear gloves when cleaning a bird, disinfect tools and surfaces, and cook the bird before freezing it. The virus is readily killed by cooking and there is no evidence that properly cooked waterfowl or domestic poultry or eggs can sicken people, WDFW said.
Anyone who walks through bird droppings or has contact with wild birds should clean their shoes and clothes, particularly if they have domestic chickens. Animals can also be a vector of disease by tracking contaminated matter between birds, Betts said.
“As always, we ask people to refrain from touching sick or dead birds or other animals, but if they have to, such as to keep a domestic animal from scavenging on it, we suggest they wear disposable gloves, double-bag the carcass, and push it way down in the garbage and secure the lid well,” Lehman said.