Blastomycosis Information for Health Care Providers
Blastomycosis is an infection caused by the fungus Blastomyces dermatitidis. This fungus is common in Northwestern Ontario; Northwestern Health Unit’s (NWHU) catchment area continues to have the highest annual rate of blastomycosis in Ontario. Between 2019 and 2023, the annual rate for NWHU ranged from 17.2-50.4 cases per 100,000 while the rest of Ontario ranged from 0.2-0.6 cases per 100,000. Blastomycosis continues to be seen throughout the region but is especially higher in the Kenora and Sioux Lookout areas.
Webinar for healthcare providers
You can watch our webinar for healthcare providers for a local context on blastomycosis.
Symptoms, testing, diagnosis, and treatment
Illness ranges from self-limiting, subclinical infection to acute or chronic pneumonia or disseminated infection, and untreated infection can cause death. Incubation ranges from weeks to months after exposure to the fungus, with a median of 45 days. Blastomycosis can mimic other respiratory and disseminated infections and diseases and will not be identified through viral or bacterial testing; specific fungal testing is required for diagnosis.
Early diagnosis and appropriate antifungal treatment is the most important mechanism for preventing morbidity and mortality related to blastomycosis.
For information on clinical manifestations, diagnosis, and treatment visit Health Canada’s page For health professionals: Blastomycosis.
For clinical practice guidelines for the management of blastomycosis, see Clinical Practice Guidelines for the Management of Blastomycosis: 2008 Update by the Infectious Diseases Society of America.
Reporting Blastomycosis
Blastomycosis has been a reportable disease under the Health Protection and Promotion Act in Ontario since 2018. Reporting allows for routine, ongoing surveillance, and the identification of endemic areas.
To report Blastomycosis, visit our Reporting Diseases of Public Health Significance page.
