An epidemic of coccidioidomycosis in Arizona associated with climate changes, 1998-2001

Background - Reports of coccidioidomycosis cases in Arizona have increased substantially. We investigated factors associated with the increase. Methods - We analyzed the National Electronic Telecommunications System for Surveillance (NETSS) data from 1998 to 2001 and used Geographic Information Systems (GIS) to map high-incidence areas in Maricopa County. Poisson regression analysis was performed to assess the effect of climatic and environmental factors on the number of monthly cases; a model was developed and tested to predict outbreaks. Results - The overall incidence in 2001 was 43 cases/100,000 population, a significant ( , test for trend) P ! .01 increase from 1998 (33 cases/100,000 population); the highest age-specific rate was in persons 65 years old (79 cases/100,000 population in 2001). Analysis of NETSS data by season indicated high-incidence periods during the winter (November-February). GIS analysis showed that the highest-incidence areas were in the periphery of Phoenix. Multivariable Poisson regression modeling revealed that a combination of certain climatic and environmental factors were highly correlated with seasonal outbreaks ( ). 2 R p0.75 Conclusions - Coccidioidomycosis in Arizona has increased. Its incidence is driven by seasonal outbreaks associated with environmental and climatic changes. Our study may allow public-health officials to predict seasonal outbreaks in Arizona and to alert the public and physicians early, so that appropriate preventive measures can be implemented.