Blastomycosis

A patient from northwestern Ontario with a persistent pneumonia, a lung mass, or new verrucous skin lesions may have more than a routine bacterial infection. Blastomycosis follows inhalation of Blastomyces conidia released when moist soil, decaying wood or leaves are disturbed. The organism is not transmitted from person to person, so isolation is not used to prevent spread between patients. The Canadian pattern matters. Endemic disease is recognised in northwestern Ontario, Manitoba, Saskatchewan and Quebec, with particularly high rates around Kenora and Sioux Lookout. Exposure may have occurred weeks earlier during camping, gardening, digging, biking, forestry or other soil-disrupting activity. Symptoms usually begin about 3 weeks to 3 months later, so the relevant exposure may not be obvious when the patient becomes ill. Blastomycosis is reportable in Ontario and Manitoba; suspected or confirmed cases should be managed with the local public health unit according to provincial requirements.