Blastomycosis is caused by the dimorphic fungus Blastomyces dermatitidis which exists as a mold in the environment and as a pathogenic yeast form in the body. The reservoir for spores is moist soil enriched with decomposing organic debris. The fungus is endemic in Ontario, Manitoba, and the southcentral, southeastern, and midwestern United States. Transmission occurs by inhalation of airborne spores after disturbance of contaminated soil.
In 2013, 34 blastomycosis cases were reported. This was a 35% increase from the 22 cases that were reported in 2012. The median age of cases was 43 years (range, 8 to 90 years), and 26 cases (76%) were male. Twenty-three (68%) cases were white, 2 (6%) were black, 4 (12%) were American Indian, 1 (3%) was of another race, and 4 (12%) were of unknown race. Twenty-five (74%) cases were hospitalized, for a median of 11 days (range, 1 to 31 days); 2 (6%) cases died as a result of their infection. Seventeen (50%) cases had pulmonary infections, 4 (12%) had extrapulmonary infections, and 9 (26%) had disseminated infections (information missing from 4 cases).
From 1999 to 2013, 479 cases were reported. The median number of cases annually was 33 (range, 22 to 49). During this time, 101 (29%) of the 354 cases for whom exposure information was available were likely exposed in St. Louis County, 31 (9%) in Itasca County, 18 (5%) in Cass County, 13 (4%) in Beltrami County, 13 (4%) in Chisago County, and 10 (3%) cases in Washington County; these counties are known to be endemic for blastomycosis in Minnesota (Figure 2).
- For up to date information see>> Blastomycosis (Blastomyces dermatitidis)
- Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2013