Cryptococcus gattii infections on Vancouver Island, British Columbia, Canada: emergence of a tropical fungus in a temperate environment.

BACKGROUND

Cryptococcus gattii causes disease among immunocompetent individuals in the tropics and subtropics. We document the appearance of C. gattii infections on Vancouver Island (VI), a temperate region, and discuss reasons for this emergence.

METHODS

Data on Cryptococcus hospitalizations for the calendar years 1995 through 2004 were reviewed. Viable historic isolates stored at the provincial public health laboratory between 1987 and 2000 were serotyped. Human cases were mapped by place of residence.

RESULTS

Cryptococcosis among HIV negative individuals diagnosed on VI increased sharply after 1999. C. gattii was not detected in stored isolates prior to 1999. C. gattii cases lived in a specific biogeoclimatic zone on VI. Higher rates of illness were associated with exposure to the central region of VI.

CONCLUSIONS

The emergence of C. gattii in a temperate region is unprecedented. Clinicians should consider C. gattii in the differential diagnosis of individuals who travelled to certain areas in British Columbia.