Rare fungal infection gains prevalence in new region

Blastomycosis is a rare but potentially fatal fungal disease caused by Blastomyces spp., a group of thermally dimorphic environmental mycoses found in moist soil and decaying organic matter. Human illness most often results in pulmonary conditions but can involve any organ system; clinical manifestations range from subclinical infection to life-threatening disease (1). Associated illness and death rates are high; among symptomatic persons, hospitalization rates are 57%–69% (25) and death rates 4%–22% (1).

Epidemiology of blastomycosis in the United States is poorly understood. Geographic areas of the United States that have historically been considered endemic, based largely on sporadic case reports and a few documented outbreaks, include midwestern, south-central, and southeastern regions of the country, particularly adjacent to the Ohio and Mississippi Rivers, Great Lakes, and St. Lawrence Seaway. In those areas, statewide annual incidence rates are ≈0.2–2.0 cases/100,000 persons (13). However, blastomycosis is not a nationally notifiable disease, and public health surveillance is limited to just 5 states: Arkansas, Louisiana, Michigan, Minnesota, and Wisconsin. The true burden of blastomycosis elsewhere is unknown.

Recent studies suggest incidence in the United States, particularly in the northeastern region, might be greater than previously understood (69). To assess the epidemiology of blastomycosis in the northeastern state of Vermont, we used insurance claims data and vital records to describe case-patient demographics, hospitalization rates, deaths, annual incidence, and geographic distribution of disease. This activity was reviewed by the Centers for Disease Control and Prevention and conducted consistent with applicable federal law and agency policy. Activity was determined to meet the requirements of public health surveillance as defined in 45 CFR 46.102(l)(2).

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