A teenager in British Columbia, Canada, is critically ill with H5N1 bird flu, marking the country's first human case of this strain. While the teen had no contact with birds or livestock, the source of infection remains unknown.

There have been dozens of confirmed human cases of bird flu in the U.S. this year. Experts discuss the symptoms, risks and how to prevent getting sick.

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.

Canada has reported H5N1 bird flu in wildlife and domestic birds. This year, there have been at least 24 reports of the virus in domestic bird facilities, including at least 10 infected premises in BC in October, according to data from the Canadian Food Inspection Agency.

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 Canadian teenager infected with bird flu — that country’s first case involving a locally acquired infection — is in critical condition and experiencing difficulty breathing, health officials said Tuesday.

British Columbia health officer Dr. Bonnie Henry shared in a news conference that a teenager, who contracted the first presumptive case of bird flu in Canada, was in critical condition after developing 'acute respiratory distress.

With 46 U.S. cases and alarming signs of the virus crossing species, experts warn of unpredictable risks if human-to-human transmission were to emerge.

Initial testing had indicated the teenager’s infection was from bird flu and was confirmed in further testing, the Public Health Agency of Canada said in a statement. The teen has been hospitalized in Vancouver since Friday and was reported in critical condition on Tuesday.