Cryptococcus gattii dispersal mechanisms, British Columbia, Canada

Recent Cryptococcus gattii infections in humans and animals without travel history to Vancouver Island, as well as environmental isolations of the organism in other areas of the Pacific Northwest, led to an investigation of potential dispersal mechanisms. Longitudinal analysis of C. gattii presence in trees and soil showed patterns of permanent, intermittent, and transient colonization, reflecting C. gattii population dynamics once the pathogen is introduced to a new site. Systematic sampling showed C. gattii was associated with high-traffic locations. In addition, C. gattii was isolated from the wheel wells of vehicles on Vancouver Island and the mainland and on footwear, consistent with anthropogenic dispersal of the organism. Increased levels of airborne C. gattii were detected during forestry and municipal activities such as wood chipping, the byproducts of which are frequently used in park landscaping. C. gattii dispersal by these mechanisms may be a useful model for other emerging pathogens.