A teenager in Canada is critically ill with the country's first human case of H5N1 bird flu. Health officials aren't sure how the youth was exposed.

A teenager in British Columbia has become the first person in Canada to test positive for the deadly H5N1 bird flu. Health authorities are urgently investigating how the virus spread, but they assure the public that the risk remains low.

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.