B.C. provincial health officer Dr. Bonnie Henry steps away from the podium after speaking during a news conference in Vancouver, on Jan. 30, 2023.DARRYL DYCK/The Canadian Press
Scientists at Canada’s top laboratory have confirmed that a British Columbia teen who is severely ill with bird flu caught a version of the highly pathogenic strain of H5N1 that has decimated farmed and wild birds across North and South America.
The Public Health Agency of Canada, or PHAC, announced the National Microbiology Laboratory’s finding Wednesday, corroborating tests performed earlier by the BC Centre for Disease Control.
The previously healthy teen from the Fraser Valley in southern B.C. is the first Canadian known to have acquired avian influenza, or H5N1, inside the country.
“I do think we should take the situation seriously,” said Theresa Tam, Canada’s Chief Public Health Officer, in an interview Wednesday.
For now, she and other public-health officials say the risk of bird flu to average Canadians is low. Human-to-human transmission is exceedingly rare, and there has been no evidence of sustained transmission between people, Dr. Tam emphasized.
However, she is concerned about how a highly pathogenic version of the bird flu known as clade 2.3.4.4b might evolve. The strain has been wreaking havoc in the animal kingdom in North and South America since it was first identified in Newfoundland in late 2021.
Here’s what you need to know about avian flu
In Canada alone, more than 11.7 million farmed birds have died or been culled after the virus was detected on more than 400 farms, according to the Canadian Food Inspection Agency (CFIA). There are 28 active outbreaks of highly pathogenic avian flu on farms in B.C. as of Wednesday, many of them in the Fraser Valley.
Dr. Tam said her concern is that, as the virus spreads rapidly and to new species, it will have more opportunity to mutate into a pathogen that transmits readily between humans.
“Year over year, this virus may be gaining some functions that we need to be very vigilant about,” she said. “And so the key is to be prepared.”
B.C. Provincial Health Officer Bonnie Henry said Tuesday that the Fraser Valley adolescent, whose age and gender have not been released for privacy reasons, is in critical condition. The patient started experiencing symptoms of pink eye, cough and fever on Nov. 2, and was admitted to BC Children’s Hospital in respiratory distress on Nov. 8.
How the teen acquired bird flu remains a mystery. The teen had no connections to farms, and none of their three dozen family members, friends and acquaintances that officials have tested so far have the virus.
Highly pathogenic H5N1 has also caused outbreaks in nearly 500 dairy herds in the United States. Bird flu has not been identified in Canadian cows. The CFIA has not found any viral traces of avian influenza virus in the hundreds of retail and unprocessed milk samples it has tested since last spring.
When National Microbiology Lab scientists sequenced the H5N1 virus that infected the B.C. teen, they found its genotype was different from that identified in U.S. cattle, which Dr. Tam said is further reassurance that Canadian cows have not been infected.