Samples from Manitoba bird die-off test positive for H5N1, but researcher says that offers some relief

WARNING: This story contains an image of a dead goose.

The Canadian Food Inspection Agency has detected a highly contagious strain of avian influenza in a number of samples collected in southern Manitoba, after what scientists have described as an unprecedented die-off of birds.

Around 500 bird carcasses, mostly Canada geese, were found near water streams in southern Manitoba during early December. Separate clusters of dead birds were found near the Red River north of Winnipeg’s Perimeter Highway, but the highest concentration was found in a group of ponds in Niverville. 

Frank Baldwin, a biologist with the Canadian Wildlife Service, told CBC News on Thursday samples of the birds were sent to the Canadian Food Inspection Agency after they tested positive for avian influenza, also known as bird flu, to determine the strain of the infection.

A spokesperson for the federal agency told CBC it submitted 39 wild bird samples to the National Centre for Foreign Animal Disease for testing on Dec. 11.  

Lab analysis confirmed 38 of the samples were positive for highly pathogenic H5N1 strain of the bird flu, the food inspection agency said. 

Hannah Wallace, a University of Manitoba researcher with expertise in viral immunology, said H5N1 is responsible for significant disease and mortality in birds, but she’s relieved samples tested positive for that strain. 

Scientists hadn’t previously seen a high mortality rate in geese with the bird flu, and Wallace was worried the virus could have mutated into a different strain, and possibly become more dangerous to birds and humans. 

There have been cases of H5N1 in people, and “the worry is that a virus that was a mix of avian and human origin would create basically a mix of the two,” she said.

“That could potentially have more severe implications for the human population.”

The samples collected tested positive for the H5N1 strain that’s most predominantly circulating among domestic poultry and wild bird populations in North America, according to the food inspection agency.

“This is not at all surprising,” Wallace said. “We’re like, ‘OK, we’ve got this.’ It’s exactly the same as what we’ve been dealing with.”

H5N1 was first detected in Canada in late 2021. Most birds in Canada have already been exposed to it, giving them some level of pre-existing immunity, Wallace said. 

Birds that are weak or underfed might be more susceptible to contracting H5N1. Wallace wonders if that was the case for the birds in southern Manitoba that died.

Following a mild early fall, they may have stayed in the province too late into the season, and then faced cooler weather and food shortages.

Lingering in the environment

Studies have also shown avian influenza can survive in the environment even if birds have migrated for the season, Wallace said. 

While she thinks it is unlikely the virus would still be in the water where the dead birds were found last year, it might still be in ponds or river sediment. Even with frigid temperatures, the virus could survive until spring, she said.

The Canadian Wildlife Service’s Baldwin says avian influenza behaves differently every year. Sometimes, birds have a high level of antibodies to fight it.

“But we don’t know exactly how long the protection persists for,” he said.

“I think it’s probably likely that we’ll see some mortality in snow geese and Ross’s geese that migrate through Canada on the way to the Arctic in April and May.”

Avian influenza has been a concern not only for scientists, but for poultry farmers in the province over the years.

Rod Wiebe, the board chair of Manitoba Chicken Producers, says the virus has been a health challenge because of how contagious and deadly it is. 

While farmers can help prevent transmission through enhanced bio-security measures, it is hard to control bird flu when the contact comes from wild birds, he said in a Thursday interview.

Farmers are generally less concerned about it during the winter, but bird flu tends to peak during fall and spring migration, Wiebe said.

“Birds move anywhere. So they can be near farms … and they can transmit the virus,” he said.

Candace Lylyk, the owner of Breezy Birds Farm in Morris, Man., said wild birds have been a concern as she tries to protect her poultry farm.

“Over the past few years, if there are any birds that land here because there’s a pond, I do everything in my power to let them move on,” she said.

But keeping the contagious virus away from her farm has also required changing how it operates. 

Lylyk is strict about not letting customers come onto the farm, opting instead for delivery. When trucks come onto the farm, their tires are sprayed.

“I am afraid of losing my livelihood and my birds,” Lylyk said. “They are family to me.”