Valley Fever

Coccidioidmycosis, also known as Valley Fever, is disease caused by a fungus called Coccidioides immitis and Coccidioides posadasii carried in the environment. When the fungi are carried in the wind as spores, they can become inhaled, causing Valley Fever. Fresno County’s geographical area is known to contain Coccidioides immitis in its soil. Coccidioides immitis is endemic to the Central Valley and the greater San Joaquin Valley, but Coccidioides posadasii also causes Valley Fever in other areas of the United States, including southern Arizona, southern New Mexico, and western Texas. Coccidioides posadasii is also endemic to certain regions in Mexico, Central America, South America, and Brazil. About 60% of people exposed will never develop symptoms; of the 40% of persons that will develop mild respiratory symptoms; about 15% of them will develop more serious disseminated disease. Persons at increased risk of becoming infected with Valley Fever in Fresno County include persons living or working outdoors in the Western Region of Fresno County. Anyone exposed to coccidioides fungal spores can become infected however African Americans, Filipinos, third-trimester pregnant females and immune-compromised people have a higher probability of developing more serious disseminated illness. 

Valley Fever Map