Wild Side: A dangerous fungus among us
By Dan Wilcox, outdoor columnist
Among the most abundant organisms on earth are the fungi. They live in the soil, in plants, in rivers and lakes, on our skin, and in us. Much of the biomass in soils is comprised of thin threads of fungi, the mycorrhizae.
Mycorrhizal fungi have mutualistic relationships with most species of plants. Plant roots provide the fungi with carbohydrates; the fungi in turn increase water and nutrient absorption to the plant roots.
Most soil fungi are beneficial. The morel mushrooms that will be popping up soon are delicious. Some fungal species are pathogenic to plants and some are to us.
Blastomycosis is a disease of people and other mammals caused by the fungus blastomyces dermatitidis. This yeast-like fungus lives in moist soil with decomposing woody organic matter. We can contract blastomycosis by inhaling the airborne microscopic-sized fungal spores. Although most people who inhale the spores don’t get sick, symptoms of blastomycosis are similar to flu or pneumonia and the infection can become serious if not treated.
The illnesses that can result from infection are highly variable. Only about half of the people infected with blastomycosis show symptoms, often three to 15 weeks after having been exposed to the fungus. Symptoms include fever, chills, cough, muscle aches, joint and chest pain. The fungus can spread to other parts of the body, causing serious problems with other organ systems.
Blastomyces dermatitidis is a naturally-occurring soil fungus endemic to the eastern U.S. and southern Canada. There are areas where there are higher incidences of occurrence of blastomycosis including the central and northern counties in Wisconsin. The blastomyces fungus thrives in wet environments such as river banks, lakes and swamps.
According to the Wisconsin Department of Public Health, it appears the Blastomyces fungus produces spores only during specific conditions. The spores become airborne when soil in which the fungus is growing is disturbed. Activities that involve disrupting the soil are likely to put a person at increased risk for acquiring blastomycosis by the inhalation of blastomyces spores.
Dogs that do their digging and hunting in wet environments are at increased risk for contracting blastomycosis. Larger male dogs and hunting breeds living near bodies of water seem to be especially vulnerable.
Blastomycosis is a relatively uncommon disease in Wisconsin with about 90 to 100 cases reported in humans each year. The number of reported cases has been increasing possibly because of increased awareness of the disease. Most cases are isolated and the disease is not communicable between people or between people and animals.
If you think that you may have blastomycosis, see your doctor. There are a number of different diagnostic tests for blastomycosis. Blastomycosis requires treatment with antifungal medicine. Itraconazole is commonly used but people with more serious infections and with compromised immune systems require other medicines. If your dog or cat is showing weakness and respiratory distress, take them to a veterinarian.
Exposure to blastomyces dermatitidis spores may be unavoidable for those of us who hike in the woods, wade in streams, do farm work, gardening or excavating in wet areas. We should be aware of this dangerous fungus among us. We should be aware of the symptoms of blastomycosis and see a doctor for treatment if need be. Illness caused by blastomycosis can be minimized by early recognition and appropriate treatment of the disease.
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