What is Coccidiomycosis?

Coccidiomycosis, colloquially called California disease, San Joaquin Valley fever, desert rheumatism, or valley fever, is a fungal infection caused by Coccidioides immitis or its cousin Coccidioides posadasii, both of which are found in the soil of the southwestern United States and northern Mexico, as well as certain parts of Central and South America. Hence, the disease is endemic to parts of Arizona, California, Nevada, New Mexico, Texas, Utah, and Mexico, meaning it is sustained in the population of these areas with no input from outside. Coccidiomycosis gets its colloquial names because of its tendency to cause outbreaks in California's prisons, with the highest incidence in San Joaquin Valley.

Coccidiomycosis is not contagious, or spread from person to person. It is usually acquired by breathing in the airborne spores, or arthroconidia, of the fungus. Coccidiodes infection caused by inhalation is called primary pulmonary coccidioidomycosis, while in primary cutaneous coccidiomycosis, the fungus enters the body through an open wound in the skin. The fungus is dormant during dry seasons, but produces spores when it rains. The spores become airborne when the soil is disrupted, such as during construction or farming.

Coccidiomycosis causes symptoms similar to those of flu, including headache, fever, cough, rash, and myalgia or muscle pain. The infection remains mild in most people, but can progress to a serious and potentially fatal condition, called disseminated coccidiomycosis or coccidioidal granuloma, in which the fungus spreads throughout the body. Serious complications can include bone lesions, heart inflammation, meningitis or inflammation of the membrane covering the brain and spinal cord, severe joint pain, severe pneumonia, skin ulcers and abcesses, and urinary tract disorders. People with weakened immune systems, men, and pregnant women are all more susceptible to the disseminated form of coccidiomycosis.

Coccidiodes infection is diagnosed by inspecting bodily fluids, particularly sputum or fluid expelled from the lungs, for the fungus or for antibodies against the fungus. Sometimes, diagnosis is made through biopsy. Any form of the disease is treated with antifungal medication. Coccidiomycosis was considered for use as a biological weapon by the United States Army during the 1950s and 1960s, but its development as a weapon did not progress past field trials. It was originally considered for use as an incapacitant, but research revealed that it would likely be fatal to a large portion of the population. In addition to humans, the disease has been known to affect a wide range of animals, including dogs, monkeys, marine animals, and cattle and other livestock.