B.C. investigating 1st presumptive human avian flu case caught in Canada

British Columbia health officials are investigating what's believed to be the first human case of avian influenza caught in Canada after a teenager tested presumptively positive for the disease, the Ministry of Health announced Saturday.

The teenager, who the ministry says is from the Fraser Health region, is currently receiving care at B.C. Children's Hospital while officials work to confirm the diagnosis and trace potential sources of exposure.

According to the statement, avian influenza — also known as bird flu — is a virus that primarily affects birds but can occasionally spread to humans through contact with infected animals or contaminated environments.

B.C.'s provincial health officer, Dr. Bonnie Henry, says the case marks the first time H5 avian influenza has been caught by a person in Canada, as far as they know, although there have been isolated cases reported in the U.S. and other countries. 

"Our thoughts are with this young person and their family during this difficult time," she said. 

Henry said a thorough investigation is underway to understand how the virus may have been contracted.

The ministry noted that public health officials are tracking contacts of the patient to monitor for symptoms and to provide guidance on testing and prevention measures.

Currently, no other human cases have been identified in connection with this incident.

Dr. Isaac Bogoch, an infectious disease specialist at Toronto General Hospital, said the virus is of particular concern because it has the potential to cause "significant clinical harm " in humans.  

"This has been a virus that's been on the radar to cause epidemics or potential pandemics," he told CBC News.

While human infections with avian influenza are rare, Health Canada says symptoms can range from mild to severe, potentially leading to pneumonia, organ failure and even death.

Since 1997, over 900 human cases have been reported globally, primarily in Asia and Africa, with about half of them resulting in death, according to Health Canada. However, the government cautions this fatality rate may be overestimated, as mild infections can often go undetected and underreported.

Another part of what makes the virus concerning, Bogoch said, is its ability to "reassort" — or swap genes — to make it more readily transmissible. 

According to the Toronto-based physician, avian flu outbreaks in the U.S. have already led to at least 44 human cases, though he said this may be a "gross underestimate."