Avian influenza still circulating

by Scott McGuigan | June 5, 2024
birds in formation avian influenza

Highly Pathogenic Avian Influenza (HPAI) or bird flu, is caused by an influenza — a virus typically associated with birds. Data collection and monitoring increased when HPAI was first detected in Ontario in early 2022. Environment and Climate Change Canada continued to monitor the situation from late summer of 2023 through to fall, testing samples across southern Ontario.

Dabbling ducks have shown a very high resiliency, rarely suffering negative consequences like death. Some other species like geese and swans were initially susceptible to the virus and many died.

The positive news is that immunity is building in ducks and Canada geese, and more importantly, they are passing some of the protection through the egg and on to their young.

“The protection that comes from surviving infection means that fewer wild birds are dying from the virus in Ontario,” ECCC Population Management Biologist Christopher Sharpe said.

“Fewer dead birds on the landscape means less transmission to scavenger species, including scavenging mammals. Hunter-shot birds, even if they were HPAI positive, represent a low risk to hunters and bird dogs, especially when handled with care.”

Avian influenza continues spreading

The downside is that the virus continues to circulate through waterfowl and other wild bird populations in Ontario. Adult dabbling ducks came into the 2023 hunting season with some immunity (47% with H5N1 antibodies), but the young of the year have much less protection coming into the fall (2% H5N1 antibodies).

As the migration peaked those percentages rose dramatically, and by December 2023, ECCC found that 91% of adults and 65% juveniles had been infected or exposed to HPAI. At the height of migration in November 2023, ECCC monitoring showed a peak of 6% of dabbling ducks were shedding H5N1 when harvested.

Hunter harvest data is an important tool to help better understand how the virus is navigating the landscape. To date, no hunters or hunting dogs have tested positive for the virus, so the likelihood of getting sick from the virus is low. But it doesn’t mean that it couldn’t happen, as H5N1 has infected humans and dogs, so ECCC and the Public Health Agency of Canada recommends taking precautions, staying vigilant, and following the guidance at: www.canada.ca/en/publichealth/services/fluinfluenza/fact-sheet-guidanceon-precautions-handling-wild-birds.html

“Hunters and the public should avoid handling sick or dead wildlife without proper personal protective equipment and similarly, do not allow pets to play with or consume sick/dead wildlife,” Sharpe said.

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