What is valley fever (coccidioidomycosis)?
Valley fever (coccidioidomycosis) is a disease caused by fungi (Coccidioides immitis and C. posadasii species) that in about 50%-75% of normal (not immunocompromised) people causes either no symptoms or mild symptoms and those infected never seek medical care. When symptoms of this fungal infection are more pronounced, they usually present as lung problems (cough, shortness of breath, sputum production, fever, and chest pains). The disease can progress to chronic or progressive lung disease and may even become disseminated to the skin, lining tissue of the brain (meninges), skeleton, and other body areas. The disease can also infect many animal types (for example, dogs, cattle, otters, and monkeys). From 1998 to 2011, the U.S. incidence has increased about tenfold to about 22,000 diagnosed individuals per year, according to the U.S. Centers for Disease Control and Prevention (CDC) although some researchers estimate the number as many as 15,000 per year.
Most microbiologists and infectious disease physicians prefer the name coccidioidomycosis because the word describes the disease as a specific fungal disease, and this term may replace valley fever in the future. This disease has several commonly used names (valley fever, San Joaquin Valley fever, California valley fever, acute valley fever, and desert fever). Other names get confused with valley fever (for example, rift or African valley fever).
People first noticed coccidioidomycosis in the 1890s in Argentina when tissue biopsies of people with the disease showed pathogens that resembled coccidia (protozoa). During 1896-1900, investigators learned that a fungus causes the disease, not protozoa, so the term "mycosis" was eventually added to "coccidia." The valley fever cases are often noted to occur in outbreaks, usually when soil is disturbed and dust arises, and when groups of people visit an endemic region (such as San Joaquin Valley or Bakersfield [in Kern County], Calif., and Tucson, Ariz., or parts of southern New Mexico or west Texas) during late summer and early fall. The disease does not spread from person to person; it is acquired from the environment via contaminated soil and dust. About 150,000 individuals are estimated to become infected each year in the U.S. This may increase, since in Arizona, the number of infected individuals as of March 2018 was 2,461 -- far more than the 1,360 during the same time in 2017.