The teenager was healthy before developing symptoms and is not known to have any contact with infected animals, health officials said.

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.

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.