Blastomycosis: a new endemic focus in Canada.

A survey of the 38 patients resident in Ontario from whose sputum, body fluids or tissues Blastomyces dermatitidis was cultured by our laboratory between 1970 and 1981 revealed a new endemic focus to the north and east of Lake Superior, where 20 of 27 traceable patients lived. Direct microscopy revealed B. dermatitidis in 90% of the cases. A lack of clinical awareness, however, had often resulted in a delay (average 15 weeks) in diagnosis. In two cases the disease was identified only at autopsy. About 80% of the patients survived.