What Canada does to monitor H5N1 avian flu

A teenager diagnosed with bird flu in British Columbia is the first domestically acquired human case of H5N1 avian influenza, the Public Health Agency of Canada says. 

Since Influenza A or flu viruses are named after the animal where they are most commonly found, avian viruses are naturally found in birds.

H5N1 is a highly transmissible and usually mild disease in geese, swans and seagulls as well as domestic birds such as chickens and turkeys. It has also spread to mammals.

Scientists at the National Microbiology Laboratory in Winnipeg sequenced the genome of the virus from the infected B.C. teen to confirm it is H5N1. The tests showed the version of the virus is related to the avian influenza viruses from the ongoing outbreak in poultry in B.C., the Public Health Agency of Canada said Wednesday.

The version is not the same as the one spreading in dairy cattle in the U.S., PHAC added. 

The H5N1 form of avian influenza remains a virus mainly found in birds.

"Based on current evidence, the risk of avian influenza infection for the general public remains low at this time," PHAC said. "The risk of avian influenza infection is higher for those who have unprotected exposure to infected animals."

That's why officials encourage people who work closely with livestock, such as poultry and dairy farmers, to wear personal protective equipment such as goggles, masks and gloves.

In British Columbia, Provincial Health Officer Dr. Bonnie Henry said in a news conference on Tuesday that humans may be infected by "inhaling the virus in aerosols, in droplets that get into the eyes, back of the throat, nose or deep into the lungs."

The one known human case in Canada is a teenager in B.C. who is in critical condition, Henry said. About three dozen people who were in contact with the teen have been tested for the virus and none have evidence of infection. 

Worldwide, "there's been very few that might have been transmitted from person to person, so in some ways this is reassuring, in that this virus doesn't seem to spread easily between people if they get infections. But it also causes very severe illness, particularly in young people," Henry told reporters. 

Henry said it's very likely that the B.C. teen's infection took place due to an exposure to either a sick animal or something in the environment, but it is a "real possibility" that researchers may never determine the source.

Since the spring of 2022, millions of poultry birds have been culled in Canada to contain an outbreak of highly pathogenic avian influenza (HPAI), including flocks in B.C.'s commercial poultry sector. 

"One of the important things that we need to do right now, recognizing that this virus is circulating in wildfowl, so geese and ducks primarily, is to be sure that if you're in contact with sick birds or dead birds that you don't touch them directly," Henry advised.