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Publication Date

4-22-2016

Keywords

Blastomyces dermatitidis, fungal ecology, mycoses, environmental exposure, blastomycosis

Abstract

Purpose

Blastomycosis is an endemic fungal infection. In rural northern Wisconsin, blastomycosis cases are associated with certain environmental features including close proximity to waterways. Other studies have associated blastomycosis with particular soil chemicals. However, blastomycosis also occurs in urban and suburban regions. We explored the geodemographic associations of blastomycosis cases in the more urban/suburban landscape of eastern Wisconsin.

Methods

We conducted a retrospective study of 193 laboratory-identified blastomycosis cases in a single eastern Wisconsin health system, 2007–2015. Controls were 250 randomly selected cases of community-diagnosed pneumonia from a similar time period. Geographic features of home addresses were explored using Google Maps. Categorical variables were analyzed with chi-square or Fisher’s exact tests and continuous variables by two-sample t-tests. Stepwise regression followed by binary logistic regression was used for multivariable analysis.

Results

Compared to pneumonia cases, blastomycosis cases were younger (47.7 vs. 55.3 years) and more likely to be male (67.9% vs. 45.6%), nonwhite (23.2% vs. 9.7%) and machinists, automobile workers/mechanics or construction workers (32.7% vs. 7.2%); P < 0.001 for all. These relationships remained significant on multivariable modeling. Case home sites, compared to controls, were more likely to have water frontage, (17.6% vs. 7.5%, P = 0.004), be > 0.5 acres (30.4% vs. 14.2%, P = 0.0002), be < 0.25 miles from an automobile repair facility or junkyard (35.9% vs. 19.4%, P = 0.0005), and be < 0.1 miles from a park, forest or farm field (54.9% vs. 39.6%, P = 0.002). Only the latter association remained on multivariable analysis.

Conclusion

Eastern Wisconsin blastomycosis case subjects were younger, more often male and more likely to live near parks/forests/fields. Novel associations of blastomycosis cases with machinery- and automobile-related occupations and/or facilities should be further explored.