British Columbia health officials have yet to identify a likely source of the infection, though none of the teen's contacts have tested positive for the virus so far.

A teenager has been left in critical condition after contracting the first presumptive human case of avian influenza in Canada. Expert Sam Scarpino discusses the health risk and potential for spread.

A teenager in Canada, hospitalized with the country's first case of the H5N1 bird flu, is in critical condition. Health officials report his condition deteriorated rapidly despite having no prior health issues.