A teenager in British Columbia was hospitalized in critical condition with the disease, and officials were working to find out how the person was exposed to the virus.

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 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.