Valley Fever

What is Valley Fever

What is Valley Fever?

Coccidioidomycosis, 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.

West Fresno County map showing elevated Valley Fever areas (yellow) around Firebaugh, Mendota, Kerman, Coalinga, and Huron; Fresno city limits shaded gray; major highways 5, 33, 41, 99, 145, and 180 marked; compass rose indicates north.

The graphic is titled “West Fresno County: Areas of Elevated Valley Fever Activity.” A county map is divided into two color regions: the western and southwestern portion is yellow, representing elevated Valley Fever regions; the rest of the county appears in green. A light gray outline shows Fresno city limits, which sit east of the highlighted area. Labeled communities within or adjacent to the yellow region include Firebaugh (northwest), Mendota (west-central), Kerman (just west of Fresno’s city limits), Coalinga (southwest), and Huron (south-central). Major California highways are drawn with route shields and numbers, including 5 along the far west, 33 running through the southwest, 41 and 99 near Fresno, 145 crossing the central-west area, and 180 running east–west near Kerman and Fresno. A compass rose at the lower right indicates orientation (north at the top). A legend explains the symbols: yellow = Elevated Valley Fever Regions; gray outline = Fresno City Limits; and route shields for California Highways.