Blastomycosis diagnosed in a nonhyperendemic area.

INTRODUCTION Blastomycosis, caused by the dimorphic fungus Blastomyces dermatitidis, is hyperendemic in northern Wisconsin and is unevenly distributed in the rest of the state and contiguous Minnesota. Clinical presentation of this illness has been characterized by localized outbreaks and sporadic cases in endemic areas. METHODS Using ICD-9 CPT codes, we queried our electronic health record system to identify cases of blastomycosis diagnosed at Gundersen Health System over a 32-year period. Gundersen serves a region outside the hyperendemic area of Wisconsin. Records so identified were reviewed for demographic and clinical features. We attempted to interview patients with a blastomycosis diagnosis from 2002 through 2006. Blastomycosis data also were collected from the states of Wisconsin and Minnesota from 2002 through 2006 and assessed for trends. RESULTS Thirty-six patients had blastomycosis diagnoses at Gundersen Health System during the study period, as identified by ICD-9 code. Of these, 10 were excluded from further review because they were either miscoded or the code indicated a previous diagnosis. The remaining 26 patients were included in the study. Premorbid conditions included diabetes (38%) and smoking (62%). The mean time from onset of symptoms to the first laboratory specimen positive for B dermatitidis was 51 days. Notably, 73% of these patients were treated initially for bacterial pneumonia. The incidence of blastomycosis in Wisconsin in the review period was 2.0 per 100,000, and the rate in Minnesota was 0.5 per 100,000. Based on the census data in Gundersen Health System's 19-county service area, the incidence of blastomycosis is 0.17 cases per 100,000. CONCLUSION In this review of blastomycosis cases diagnosed outside the hyperendemic area of northern Wisconsin, diagnosis was often delayed, and 4 patients whose infections might have been treatable died. Although uncommon, blastomycosis needs to be considered in the differential diagnosis in areas outside the hyperendemic area.