VALLEY FEVER

Valley Fever (Coccidioidomycosis) is primarily a disease of the lungs that is common in the southwestern United States and northwestern Mexico. It is caused by the fungus Coccidioides sp., which grows in soils in areas of low rainfall, high summer temperatures, and moderate winter temperatures. These fungal spores become airborne when the soil is disturbed by winds, construction, farming and other activities.

Valley Fever infections are more likely to occur during certain seasons. In Arizona, the highest prevalence of infections occurs June through July and from October through November. In California, the risk of infection is highest from June through November, without the late summer break.

It is estimated that there are about 150,000 infections in the southwestern U.S. each year. Approximately one-third of these results in a self-limited, although often protracted, respiratory illness. However, in a small percentage the illness is more serious and potentially lethal.

In susceptible people and animals, infection occurs when a spore is inhaled. Within the lung, the spore changes into a larger, multicellular structure called a spherule. The spherule grows and bursts, releasing endospores which develop into spherules. Valley Fever symptoms generally occur within three weeks of exposure. Valley Fever is not a "contagious" disease, meaning it is not passed from person to person. Second infections are rare.

Many domestic and native animals are susceptible to the disease, including dogs, horses, cattle, sheep, burros, coyotes, rodents, bats and snakes.

For more information:
Valley Fever Center for Excellence
Mail Stop 1-111(INF), 3601 S. 6th Avenue, Tucson, Arizona 85723