The Emergence of Cryptococcus gattii Infections on Vancouver Island and Expansion in the Pacific Northwest

Abstract

This chapter outlines issues that were quickly explored, starting with the realization in 2001 that Vancouver Island was a hot spot for a pathogen not previously described as endemic and not restricted to tropical and subtropical climates. The picture of the outbreak that has developed has implications for global travel, climate change, land use patterns, and environmental colonization. Importantly, cryptococcosis caused by Cryptococcus gattii now serves as an excellent illustration of the impact of pathogen spread into a clement ecological niche, in this case, one that happened to be in a major population center of western Canada and the Pacific Northwest. Symptoms and clinicopathological changes in animals on Vancouver Island were consistent with disease reported elsewhere. The most common primary system involved was respiratory, followed by the central nervous system (CNS), in both cats and dogs. Animal cryptococcosis due to C. gattii is a nonregulated disease in Canada. Molecular typing of C. gattii environmental isolates from Vancouver Island using PCR fingerprinting and/or restriction fragment length polymorphism methodologies revealed that the majority of isolates belonged to the VGII molecular type and a small number belonged to the VGI molecular type. A number of solid culture media, biochemical tests, and stains can confirm the diagnosis of Cryptococcus to the genus level. Ecological niche modeling was employed to identify geographical areas in British Columbia with suitable environmental conditions to support the permanent colonization of C. gattii in the environment.