A Canadian teen is hospitalized in critical condition with what is believed to be bird flu, a British Columbia health official said Tuesday.

It’s not clear how the teenager picked up the virus, which has been detected recently in wild birds and poultry in the province, said Dr. Bonnie Henry, provincial health officer. The teen is not known to have any contact with infected animals, she said.

Officials have released few details about the patient. Henry said the teen was healthy before developing symptoms more than a week ago — initially eye redness, cough and fever — and has been hospitalized with a respiratory illness since Friday in Vancouver.

Initial testing indicated the infection is from bird flu. Officials believe it is the Type A H5N1 bird flu, but are awaiting confirmation. H5N1 has been spreading widely in the U.S. among wild birds, poultry, cows and a number of other animals. 

In Canada, testing has been done on about three dozen people who were in contact with the teen. None of them have evidence of infection, Henry said.

Officials are trying to figure out how the teen was infected, although Henry said that may never be determined. In British Columbia, the virus has been detected in poultry, wild birds and some small animals, mostly when birds are migrating through the area.

The Canadian case was in the Fraser Valley area in southern British Columbia.

So far this year, at least 46 people in the U.S. — mostly farmworkers — have tested positive with mostly mild symptoms.

According to the U.S. Centers for Disease Control and Prevention, 21 of those patients were in California, 11 in Washington, 10 in Colorado, two in Michigan and one each in Missouri and Texas.

The source of the disease was traced to either cattle or poultry in all but one of the U.S. cases. The source in the lone Missouri case was unknown, the CDC said.