A teen in British Columbia remains in critical condition in what it's believed to be Canada's first human case of the avian flu, Dr. Bonnie Henry says.

Provincial health officer Henry provided an updated Tuesday (Nov. 12) after She added there has been no link to to any of the affected poultry farms in B.C. with infected flocks. 

It's the second case ever detected in Canada, with the first an Alberta resident in 2014 when a person acquired it while travelling in China. 

But Henry said this is the first known human case acquired in Canada. 

The teen, who is from the Fraser Health region, was admitted to BC Children's Hospital on Friday.

Henry said the initial symptoms started with conjunctivitis – an infection in the eyes – along with a fever and cough.

"Those are really the hallmarks that's very difficult early on to determine if that is from influenza, from COVID, from other respiratory viruses."

Henry said public health teams are now looking at who, or what, the teen has been in contact with.

"As you can imagine, this is painstaking and challenging work," she said, adding the teen's family has been sharing information with the team as best as they can. 

"Having said that, I must caution that there is a very real possibility we may not ever determine the source, but at this point we have a number of leads that we're following."

Henry added there were a variety of animals the teen was in contact with, including dogs, cats and some reptiles, but no birds that public health teams are aware of. There was a dog that was sick and advanced testing has been done on the animal. 

Public health working on contact tracing

Public health is now working on a thorough investigation into contact tracing, she said, "to make sure that there are not other cases out there that we're missing, to making sure that people who have been in contact with this young person during their infectious period are assessed, are tested."

She said about three dozen people have been tested so far to make sure there are no "hidden or asymptomatic or mild infections out there." Henry added people have been offered prophylaxis with an antiviral medication to prevent them from developing symptoms. 

So far, no one else has been identified as being sick.

She said it's still being called a "presumptive positive" case until it can be confirmed at the country's national laboratory in Winnipeg, but her office has confidence that it is a bird flu case.Henry said B.C. has a very robust surveillance system for respiratory illnesses, including influenza, COVID-19 and RSV.

Confirmation is expected in the next few hours, she added.

Henry said the B.C. Centre for Disease Control is doing whole genome sequencing to "understand what exactly this virus is." She said it's something that has seen value since the COVID-19 pandemic. 

In B.C., Henry said wastewater testing has been valuable "to help understand what's circulating in the community." It's something that started during the pandemic. 

"We are looking for H5 in some of the wastewater samples. The challenge, though, however, is we can't tell if it comes from humans or if it comes from birds and other animals that get into the wastewater from the environment. 

Avian flu activity in B.C. and beyond

B.C. has seen an increase in H5N1 activity in recent years. It's the sixth season of seeing expanded outbreaks in waterfowl, Henry said.

As of Tuesday morning, avian flu has affected 26 premises across B.C., predominantly in the Lower Mainland. Henry said those cases are usually aligned with migratory waterfowl, such as geese and ducks, that migrate from the north and fly south at this time of year. 

, a petting farm lost its entire flock to the virus. were hit by the flu in October. 

This most recent strain of H5NI began circulating in North America in 2022. Since then about 11 million birds have been destroyed on infected premises, with "the vast majority of them here in British Columbia."

Henry said H5N1 really started circulating in Hong Kong in 1997, and there have been sporadic outbreaks primarily in southeast or south Asia. Since then, there have been as many as 900 cases globally. 

There has only been one other human case identified in Canada. That was in Alberta in 2014.

How humans can get infected

Henry said human can catch avian flu by "inhaling the virus in aerosols, in droplets that get into the eyes or the back of the throat and nose or deep into the lungs."

In the U.S. this year, there have been 46 human cases identified. Most of them have been dairy workers where the virus got into the herds. Those have been predominantly mild cases, with conjunctivitis or mild respiratory symptoms. 

"What we've learned is that this virus can be alive in milk, and particularly unpasteurized milk can be a mode of transmission."