Cattails
Blastomycosis: Rare disease prevalent in northern Wisconsin
Northern Wisconsin has many fine attributes. Blastomycosis, a rare infectious disease, is not one of them.
The airborne disease is caused by the fungus Blastomyces dermatitidis, which is found in organically rich soil. “Conditions must be right for the fungus to thrive. The moist, humid, cooler conditions in northern Wisconsin, especially bodies of water and where the soils have been disturbed, seem to be prime spots,” said Laura Nelson, M.D., medical director at Marshfield Clinic Minocqua Center. She became interested in the disease during her first year of medical practice as a hospitalist when she treated two patients with the disease.
When inhaled, the fungus can cause lung infection characterized by a persistent cough, shortness of breath, low-grade fever or skin lesions, Dr. Nelson said. Blastomycosis symptoms are similar to pneumonia and often last more than two weeks. A sputum sample is used to diagnose blastomycosis, and more than one test may be needed. Blastomycosis also can spread through blood to skin, bones, liver and brain.
The fungus typically is found in the spring through fall when soil is exposed. But because it may take weeks or months for the disease to develop, blastomycosis can be diagnosed at any time of the year,
Dr. Nelson said. “Your immune system is trying to keep it in check.” Blastomycosis may be overlooked in the winter months when people think they have upper respiratory illness.
Some people have blastomycosis for several weeks before they realize they are ill. Others become extremely ill quickly. According to the most recent statistics available, nine people died of blastomycosis in Wisconsin in 2006. Some strains of blastomycosis may be more aggressive, or the infected person’s immune system may be weakened for some other reason, such as cancer, rheumatoid arthritis or diabetes, she said.
People who fish, hunt, garden or work outdoors are more susceptible, but anyone can get the airborne disease. Common in dogs, it cannot pass between humans or animals and humans. “You don’t need to be afraid. You should be knowledgeable about blastomycosis and respect it,” Dr. Nelson said.
No vaccine is available to prevent blastomycosis, and it cannot be detected in the soil. Researchers are working on more reliable testing, perhaps through a blood sample, Dr. Nelson said. “The good news is it’s very treatable. Anti-fungal medications, taken orally or intravenously, are effective for most.”
If you’re concerned
If you have a persistent respiratory illness, a cough that produces dark phlegm or skin lesions that don’t heal, see your family doctor or urgent care provider, Laura Nelson, M.D., advised. “Tell your doctor, ‘I’m concerned about blastomycosis, I live in an area where it’s prevalent.'"
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