Integrated Epidemiological Study of Valley Fever

Occurrence of Valley Fever and Environmental Sampling

The incidence of valley fever is clearly dependent on spatial and temporal factors; however, they are poorly understood. The resolution of disease incidence has not improved much from the map produced by Dr. Ochoa in 1976.

A previous study showed that prevalence of valley fever in dogs is significantly different between areas with different soil types and levels of urbanization. This study builds upon those results and is evaluating valley fever at the neighborhood level of resolution for cases and the submeter level of resolution for the fungus' occurrence in the soil. This increased resolution of study may help improve intervention and prevention strategies by better understanding the spatial structure of fungal occurrence in the soil. For example, is the occurrence of disease and the pathogen uniform and at what scale? Is occurrence random, highly variable, or predictable? Does occurrence show structure?

We are sampling soils from the yards of case households and in undisturbed areas around
Tucson for isolation and identification of the fungus. Detailed soil and vegetation descriptions
of positive and negative sites may improve the understanding of the fungus' occurrence.