This marked "the first detection of a presumed human case" of H5 in Canada, authorities in British Columbia said. A Canadian teen remains in critical condition at a children's hospital with what is believed to be bird flu, a British Columbia health official has said. It’s not clear how the teenager picked up the virus, which has been detected recently in wild birds and poultry in the province, said Dr Bonnie Henry, British Columbia's provincial health officer.

The teen is not known to have any contact with infected animals, she said. Officials have released few details about the patient. Henry said the teen was healthy before developing symptoms more than a week ago which included eye redness, cough and fever, and has been hospitalised with a respiratory illness since Friday in Vancouver.

Initial laboratory testing indicated the infection is from bird flu. Officials believe it is the Type A H5N1 bird flu but are awaiting confirmation. "It is called a presumptive positive .

.. (but) it needs to be confirmed at the National Microbiology Laboratory in Winnipeg," Henry said, adding that they would have the confirmation soon.

H5N1 has been spreading widely in the US among wild birds, poultry, cows, and a number of other animals. There have been 46 people in the US, who are mostly farmworkers, that tested positive with mostly mild symptoms. Recently, it was detected in a US pig for the first time, raising concerns about the virus' potential to affect humans.

In Canada, testing has.