Epidemiology and Clinical Spectrum of Blastomycosis Diagnosed at Manitoba Hospitals

Abstract

Blastomyces dermatitidis is a dimorphic fungus endemic to Canada and the United States. Few reports regarding blastomycosis in Canada have been published. We retrospectively reviewed the medical charts of 143 patients with confirmed cases of blastomycosis diagnosed in hospitals in Manitoba, Canada, from 1988 through 1999. The annual incidence rate of blastomycosis in Manitoba was 0.62 cases per 100,000 population, compared with 7.11 cases per 100,000 population in the Kenora, Ontario district. The average age of patients was 38.0 years, and males accounted for 65.0% of cases. An increased incidence of blastomycosis was observed in the Aboriginal subpopulation. Organ systems involved were as follows: respiratory system (93.0% of cases), skin (21.0%), bone (13.3%), genitourinary tract (1.4%), and the central nervous system (1.4%); 6.3% of patients died, and death was associated with a short clinical course. This study provides a summary of the current status of blastomycosis in this area of endemicity in Canada.

Hemorrhagic pustules in an Aboriginal man

“…5 In this region, retrospective epidemiologic analysis has found that the symptomatic incidence rate is 7.11 cases per 100 000 people, or about five times the reported incidence rate in Mississipi and Wisconsin (1.3 and 1.4 cases per 100 000 people, respectively). 5,6 Blastomycosis is acquired by the inadvertent inhalation of conidia; these are produced by the mycelial form of the fungus, which exists in nature. 5,7 The infectious conidia are transformed in the lungs into the yeast form, causing clinical blastomycosis if the infection is not controlled by the cell-mediated immune response.…”

“…4,5 Although uncommon, the disease is endemic to the Ohio and Mississippi River basins and in the Canadian provinces and American states that border the Great Lakes, and is hyperendemic in the area of northwestern Ontario surrounding Lake of the Woods (Kenora, Ontario). 5 In this region, retrospective epidemiologic analysis has found that the symptomatic incidence rate is 7.11 cases per 100 000 people, or about five times the reported incidence rate in Mississipi and Wisconsin (1.3 and 1.4 cases per 100 000 people, respectively). 5,6 Blastomycosis is acquired by the inadvertent inhalation of conidia; these are produced by the mycelial form of the fungus, which exists in nature.…”

“…5,6 Blastomycosis is acquired by the inadvertent inhalation of conidia; these are produced by the mycelial form of the fungus, which exists in nature. 5,7 The infectious conidia are transformed in the lungs into the yeast form, causing clinical blastomycosis if the infection is not controlled by the cell-mediated immune response. 4,5 Disease onset may be acute, occurring shortly after exposure, or it may be the result of reactivation following a remote exposure.…”

“…5,7 The infectious conidia are transformed in the lungs into the yeast form, causing clinical blastomycosis if the infection is not controlled by the cell-mediated immune response. 4,5 Disease onset may be acute, occurring shortly after exposure, or it may be the result of reactivation following a remote exposure. 4,5 An outbreak investigation in Wisconsin found that infection rates following exposure appear to be high but that fewer than 50% of infected individuals develop clinically apparent disease.…”

A Review on Superficial Fungal Infections: Clinical Symptoms and Treatment

“…It affects humans as well as animals. Soil, decaying vegetation are the common habitat of this disease and it is common along waterways [23] . The causative agent of blastomycosis is Blastomyces dermatitidis which is dimorphic fungus that develop as amould in the environment and as yeast in the tissue [24] .…”