A Decade of Experience: Cryptococcus gattii in British Columbia

Abstract

It has been over a decade since Cryptococcus gattii was first recognized as the causative organism of an outbreak of cryptococcosis on Vancouver Island, British Columbia. A number of novel observations have been associated with the study of this emergent pathogen. A novel genotype of C. gattii, VGIIa was described as the major genotype associated with clinical disease. Minor genotypes, VGIIb and VGI, are also responsible for disease in British Columbians, in both human and animal populations. The clinical major genotype VGIIa and minor genotype VGIIb are identical to C. gattii isolated from the environment of Vancouver Island. There is more heterogeneity in VGI, and a clear association with the environment is not apparent. Between 1999 and 2010, there have been 281 cases of C. gattii cryptococcosis. Risk factors for infection are reported to be age greater than 50 years, history of smoking, corticosteroid use, HIV infection, and history of cancer or chronic lung disease. The major C. gattii genotype VGIIa is as virulent in mice as the model Cryptococcus, H99 C. neoformans, although the outbreak strain produces a less protective inflammatory response in C57BL/6 mice. The minor genotype VGIIb is significantly less virulent in mouse models. Cryptococcus gattii is found associated with native trees and soil on Vancouver Island. Transiently positive isolations have been made from air and water. An ecological niche for this organism is associated within a limited biogeoclimatic zone characterized by daily average winter temperatures above freezing.

Cryptococcus gattii Infections

“…Table 4 summarizes the pertinent epidemiological and clinical features in case series involving three or more patients. In addition, a number of reviews, editorials, and book chapters with substantive discussion on C. gattii clinical epidemiology and infection in humans have been published since 2000 (39,85,122,(254)(255)(256)(257)(258)(259)(260)(261)(262)(263)(264)(265).…”

Cryptococcosis due to Cryptococcus gattii in Germany from 2004–2013

“…Infections were associated with mortality in 8.7% (Galanis et al, 2010). The predominant outbreak strains, including the major molecular type (VGIIa) have been isolated from trees and soil in British Columbia (Bartlett et al, 2011). Phylogenetic studies suggest that these strains may have been introduced into the region from South America (Hagen et al, 2013).…”

Defects in Phosphate Acquisition and Storage Influence Virulence of Cryptococcus neoformans

“…Approximately one million new cases of this disease and Ͼ600,000 fatalities are estimated to occur every year, and immunocompromised people are particularly at risk (2). The sister species Cryptococcus gattii recently emerged as a primary pathogen causing infections in otherwise healthy individuals in North America (3,4). C. neoformans and C. gattii are acquired by inhalation of spores or desiccated yeast cells, and in the absence of immune containment, fungal cells spread systemically and cause meningoencephalitis.…”