Serological evidence of increased Coccidioides immitis infections in western Canada in 1996.

OBJECTIVE

To investigate the epidemiology of Coccidioides immitis infection in persons returning to western Canada from C immitis endemic zones in southwestern United States.

DESIGN

Review of C immitis serology requests from 1996.

METHODS

Data were based on review of enzyme immunoassay and immunodiffusion results from 1993 to 1996 inclusive. Detailed information on clinical presentation, treatment and outcome of disease process was obtained through questionnaires and interviews with physicians who submitted Coccidioides serology requests in 1996.

RESULTS

Positive serology for C immitis increased from 4.7% to 5.2% (between 1993 and 1995 inclusive) to 10.7% in 1996. Enzyme immunoassay for immunoglobulin G and/or immunoglobulin M or immunodiffusion was positive in 25 patients in 1996. The mean age of these patients was 62 years, and the predominant clinical presentation was pulmonary infiltrate with fever. All patients with positive serology were known to have travelled to central or southwestern Arizona or southern California.

CONCLUSIONS

Travel to a defined coccidioidomycosis endemic zone presents a risk for the older traveller. Serology for C immitis supported the clinical, histological and microbiological diagnoses in patients who had travelled to this defined endemic zone.