Evaluation of risk factors for Cryptococcus gattii infection in dogs and cats

Objective-To determine risk factors associated with Cryptococcus gattii infection in dogs and cats residing on Vancouver Island in British Columbia, Canada. Design-Matched case-control study. Animals-20 dogs and 29 cats with C gattii infection and matched controls. Procedure-Dogs and cats with a confirmed or probable diagnosis of cryptococcosis resulting from infection with C gattii were enrolled by veterinarians, and owners completed a questionnaire designed to obtain information pertaining to potential risk factors for the disease. Owners of matched control animals were also interviewed. Odds ratios and 95% confidence intervals or paired t tests were calculated to determine significant associations. Results-Animals were enrolled during 2 noncontiguous periods in August 2001 to February 2002 (8 dogs and 9 cats enrolled) and May to December 2003 (12 dogs and 26 cats enrolled). Risk factors significantly associated with development of cryptococcosis included residing within 10 km of a logging site or other area of commercial soil disturbance, above-average level of activity of the animal, travelling of the animal on Vancouver Island, hunting by the animal, and owners hiking or visiting a botanic garden. Conclusions and Clinical Relevance-Results indicated that dogs and cats that were active or that lived near a site of commercial environmental disturbance had a significantly increased risk of developing C gattii infection. Veterinarians should communicate these risks to owners in context because cryptococcosis was an uncommon disease in this population.