Public Health Alert – Increase in local cases of Blastomycosis
Situation
Although it is known that Northwestern Health Unit’s (NWHU) catchment area has the highest rate of blastomycosis in Ontario (2019-2023 annual rate per 100,000 17.2-50.4 in NWHU, 0.2-0.6 in the rest of Ontario), this alert is to inform you that there has been an increase in reported blastomycosis cases for the month of October.
Issue
It is respiratory illness season and Blastomycosis can mimic other respiratory illnesses. Blastomycosis symptoms can seem to improve and then worsen. That means other treatments may seem to work temporarily, which can delay treatment and increase the risk of negative outcomes. Untreated infection can lead to death.
Incubation ranges from 21-106 days after exposure to the fungus, with a median of 43 days. Illness ranges from self-limiting, subclinical infection to acute or chronic pneumonia or disseminated infection. Disseminated infections and diseases will not be identified through viral or bacterial testing; specific fungal testing is required for diagnosis.
Early diagnosis and appropriate antifungal treatment are the most important mechanism for preventing morbidity and mortality related to Blastomycosis.
Requested actions
- Please continue to consider Blastomycosis infection when assessing patients in the region.
- Health care providers who are newer to Northwestern Health Unit’s catchment area may be unfamiliar with Blastomycosis because it is so uncommon elsewhere. Please refer to NWHU’s website for more information
- Recommended tests include:
- Sputum sample and/or lesional material for direct visual exam by microscopy and fungal culture. Where possible, submit multiple specimens for microscopy/culture over time to increase sensitivity. A sputum specimen which is mainly saliva is not an adequate specimen for diagnosis and may lead to false negative resultsSerology testing is available, but the sensitivity is poor and are generally not recommended; It is not suitable for acute diagnosis or for some immunocompromised patientsAntigen testing: requires to be sent to the USA for processing. It is sensitive however there is considerable cross-reactivity with other fungi. It may be suitable when collection of respiratory specimens is challenging
- See Public Health Ontario for further information
For more information on Blastomycosis in our region, what it is, and how it is acquired, please see the September 10, 2024, Public Health Alert.
Resources
- Northwestern Health Unit – Blastomycosis Information for Health Care Providers
- PHO Webinar: Blastomycosis in Ontario: Public health and clinical considerations
- Public Health Agency of Canada – Blastomycosis for health professionals
- Public Health Ontario – Blastomycosis
- Public Health Ontario Laboratory Testing Index
Contact:
Dr. Kit Young Hoon, MPH, MSc., FRCPC
Medical Officer of Health
Northwestern Health Unit