A laboratory-based surveillance of human blastomycosis in Wisconsin between 1973 and 1982

Blastomycosis appears to be prevalent in states around the Great Lakes. However, its incidence in these states has not been reported. The Wisconsin Division of Health established a laboratory-based surveillance for human blastomycosis in Wisconsin to estimate disease incidence and identify endemic areas in the state for the interval 1973 to 1982. Certified mycology and pathology laboratories in Wisconsin and at two major medical centers in Minnesota were surveyed for all laboratory isolates and identifications in tissue of Blastomyces dermatitidis obtained in Wisconsin residents during 1973-1982. A total of 235 isolates and identifications of B. dermatitidis were obtained; 214 (88%) Wisconsin laboratories participated. It was estimated that the annual incidence of blastomycosis in Wisconsin for 1973-1982 ranged between 0.32 and 0.72 cases per 100,000 total population (mean, 0.48 cases/100,000 population). Cases were reported in residents from 40 (56%) of the 72 Wisconsin counties. Residents of seven counties in northern and central Wisconsin had significantly higher incidences of blastomycosis than residents of other counties in which cases were documented. The incidence of blastomycosis in Wisconsin for 1973-1982 is similar to that noted in Mississippi, Kentucky, and Arkansas where this disease is thought to be endemic and where similar surveys have been performed.