The emergence of Cryptococcus gattii in British Columbia and the Pacific Northwest

Abstract

An unprecedented emergence of cryptococcal infections in animals and otherwise healthy humans was recognized in 1999 on the east coast of Vancouver Island, British Columbia. Unexpectedly, these infections were caused by Cryptococcus gattii, a species closely related to the AIDS-associated fungal pathogen Cryptococcus neoformans. Human cases have continued over the past 8 years and now total approximately 170 with eight deaths. Extensive environmental sampling, coupled with detailed molecular typing of isolates, revealed areas of permanent and transient colonization with primarily three genotypes of the fungus. C. gattii was found in air, soil, water, and in association with numerous tree species. Importantly, there is solid evidence for human-mediated dispersal of the pathogen, and C. gattii has now been detected in the environment on the mainland of British Columbia and in the Pacific Northwest. Associated animal and human cases are now being reported and further spread of the pathogen may be inevitable.