Blastomycosis

Blastomycosis (blasto) is a rare fungal infection caused by breathing in the fungus Blastomyces dermatitidis.

About half of people exposed to the fungus will develop mild to severe illness. Symptoms can appear between 3 to 15 weeks after exposure.

Infection may result in a flu-like illness with fever, chills and cough. Some patients develop a serious lung infection. When blastomycosis spreads, it can affect many areas of the body, including the skin, bones and genitourinary tract (the reproductive organs and urinary system).

Exposure occurs by inhaling airborne fungal spores or by the fungus entering a scrape or cut. Farmers, forestry workers, hunters and cottagers may be exposed at wooded sites if contaminated soil gets disturbed. Fortunately, the fungus grows only under specific conditions and is understood to be a relatively uncommon cause of infection.

The fungus grows in thickly wooded areas and along streams and rivers, where there is:

• moist soil and leaves
• rotting plants and wood

The presence of Blastomyces dermatitidis may be indicated by a white or tan mold in moist soil and decaying wood, but may also be present without any distinguishing signs.

The fungus is found in acidic, moist soil in parts of northern Ontario, Manitoba, Saskatchewan, Quebec and in other areas around the Great Lakes, as well as the Mississippi River Valley. It is understood that the Sudbury and Manitoulin districts are endemic for blastomycosis.

If you have a persistent cough, muscle aches, joint pain, tiredness, chills, low-grade fever, skin sores or unexplained weight loss, tell your doctor that you may have been exposed to the fungus that causes blastomycosis. The doctor will want to know if you have been in a higher-risk area and in contact with moist soil.

Without treatment, blastomycosis can become a serious illness. The diagnosis can be made from a sample of saliva, urine or skin lesions, depending on symptoms. After diagnosis, prompt treatment is very important and may be required for several months.

Even if you work, live, or vacation in the areas where the fungus grows, it is important to remember that blastomycosis is a rare condition and the risk of getting it is very low. If your immune system is weakened, you should avoid activities that require working with soil.

To reduce exposure to blastomycosis when you are working in moist soil areas where the fungus may grow such as under the house, cottage, porch, or shed, wear:

• work gloves
• proper footwear
• long pants
• long-sleeved shirts
• a disposable NIOSH N100 approved HEPA filter dust mask