Sources of Blastomycosis
Where does Blastomyces live?
Blastomyces lives in the environment, particularly in moist soil and in decomposing organic matter such as wood and leaves. In the United States, the fungus mainly lives in the midwestern, south-central, and southeastern states, particularly in areas surrounding the Ohio and Mississippi River valleys, the Great Lakes, and the Saint Lawrence River.1,2 The fungus also lives in Canada,3-4 and a small number of blastomycosis cases have been reported from Africa5 and India.6
These maps show CDC’s current estimate of where the fungi that cause blastomycosis live in the environment. These fungi are not distributed evenly in the shaded areas, might not be present everywhere in the shaded areas, and can also be outside the shaded areas.
Life cycle of Blastomyces
Blastomyces lives in the environment as a mold that produces fungal spores. The spores are too small to see without a microscope. When people or animals breathe in the spores, they are at risk for developing blastomycosis. After the spores enter the lungs, the body temperature allows the spores to transform into yeast. The yeast can stay in the lungs or spread through the bloodstream to other parts of the body, such as the skin, bones and joints, organs, and central nervous system (brain and spinal cord).
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I’m worried that Blastomyces is in the soil near my home. Can someone test the environment to find out if the fungus is there?
No, in this situation, testing the environment for Blastomyces isn’t likely to be useful. When a soil sample tests positive for Blastomyces, it isn’t necessarily a source of infection, and when a sample tests negative, that doesn’t necessarily mean that the fungus isn’t in the soil. Also, there are no commercially-available tests to detect Blastomyces in the environment. Testing environmental samples for Blastomyces is currently only done for scientific research.
- Furcolow ML, Busey JF, Menges RW, Chick EW. Prevalence and incidence studies of human and canine blastomycosis. II. Yearly incidence studies in three selected states, 1960–1967external icon. Am J Epidemiol. 1970;92(2):121–31.
- Bradsher RW, Chapman SW, Pappas PG. Blastomycosisexternal icon. Infect Dis Clin North Am. 2003;17(1) 21-40, vii.
- Morris SK, Brophy J, Richardson SE, Summerbell R, Parkin PC, Jamieson F, et al. Blastomycosis in Ontario, 1994-2003external icon. Emerg Infect Dis. 2006 Feb;12(2):274-9.
- Litvinov IV, St-Germain G, Pelletier R, Paradis M, Sheppard DC. Endemic human blastomycosis in Quebec, Canada, 1988-2011external icon. Epidemiol Infect. 2013 Jun;141(6):1143-7.
- Cheikh Rouhou S, Racil H, Ismail O, Trabelsi S, Zarrouk M, Chaouch N, et al. Pulmonary blastomycosis: a case from Africaexternal icon. ScientificWorldJournal. 2008 Nov 2;8:1098-103.
- Chakrabarti A, Slavin MA. Endemic fungal infections in the Asia-Pacific regionexternal icon. Med Mycol. 2011 May;49(4):337-44.