Epidemiology of Blastomycosis in a Region of High Endemicity in North Central Wisconsin

Abstract

The clinical and epidemiologic features of 73 patients with laboratory-confirmed blastomycosis who were identified over an 11-year period in North Central Wisconsin are presented. Pulmonary disease was the sole manifestation in 77% of patients. More than one-half of all patients had symptoms that included fever, cough, weight loss, night sweats, and pleuritic chest pain. Virtually all were previously healthy, and most did not have an outdoor occupation. However, 82% of these patients lived or had visited within 500 m of rivers or associated waterways. The majority experienced the onset of symptoms between December and April. The estimated mean annual incidence rate of infection for Vilas County was 40.4 cases per 100,000 persons, and that for the largest city in the county was 101.3 cases per 100,000 persons. Several areas with an exceptionally high incidence of the infection were observed. We suggest that, in regions where blastomycosis is hyperendemic, clinical disease is most often pulmonary and occurs in immunocompetent individuals and that residence near an ecological focus may be a greater risk factor for acquisition of blastomycosis than is occupation.

Blastomyces Antigen Detection for Diagnosis and Management of Blastomycosis

“…Marshfield Clinic is located in Wisconsin where blastomycosis is endemic (1,3,6,9,(23)(24)(25)(26)(27)(28). Research protocols were approved by the Marshfield Clinic Institutional Review Board.…”

“…Blastomycosis may be asymptomatic or it can present as isolated pulmonary disease, disseminated disease (pulmonary and extrapulmonary infection), or extrapulmonary disease with manifestations in the central nervous system, bone, skin, or other locations (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11).…”

Blastomycotic Multifocal Arthritis and Osteomyelitis in the Urban Setting

“…Humans acquire this fungus by inhalation of spores from the soil, usually in rural settings 3 . Infection by blastomycosis is most frequently found in adults aged 20-50 years 4,5 , with annual incidence reported in up to 100 cases per 100,000 people in specific areas of the United States 6 . In children, cases are infrequent, accounting for 3%-10% of total reported cases, with pneumonia being the most common manifestation 7 .…”

Systemic Blastomycosis Diagnosed by Prostate Needle Biopsy

“…2,3 Vilas County, WI has been the site of 3 major outbreaks of blastomycosis 1,14,15 and reports human incidence as high as 100/100,000 per year in the southeastern region of the county, inclusive of the city of Eagle River. 16,17 The fungi are indigenous to broad geographic regions worldwide (North America, India, Africa, South and Central America) but reproduce successfully in only a very specific "micro-niche." 11 The innocuous spores are rarely isolated in nature but case analyses implicate decaying wood and podzolic soils with high organic content, possibly enriched with bird and animal feces, and formed under moist, cool and acidic conditions.…”