Valley Fever (Coccidioidomycosis) Statistics
In 2019, there were 20,003 cases of Valley fever reported to CDC. Most of these cases were in people who live in Arizona or California. Rates of Valley fever are typically highest among people age 60 and older.
The number of Valley fever cases reported to CDC likely underestimates the true number of Valley fever cases. Tens of thousands more illnesses likely occur and may be misdiagnosed because many patients are not tested for Valley fever. In highly endemic areas such as the Phoenix and Tucson metropolitan areas of Arizona, Valley fever causes an estimated 15% to nearly 30% of community-acquired pneumonias, but low testing rates suggest that Valley fever is probably under-recognized. 1,2
Valley fever is reportable in certain states. State health departments collect information about cases of Valley fever and then send the information to CDC through the National Notifiable Diseases Surveillance System (NNDSS). Weekly and annual data are available on the NNDSS website. Check with your local, state, or territorial public health department for more information about disease reporting requirements and procedures in your area.
California’s 2019 case counts are reported directly from the state and may differ from NNDSS totals, which may have incomplete data due to the coronavirus disease 2019 (COVID-19) pandemic.
|Year||Arizona||California||Nevada, New Mexico, and Utah||Other states||Total|
Case counts reviewed and modified as of 04/19/2022.
The numbers reported here represent finalized annual NNDSS data. Case counts reported by individual states might differ slightly from those reported here because of differences in the timing of reports or surveillance methods.3,4
The reasons for the year-to-year changes in the number of reported Valley fever cases are not entirely known, but could be due to changes in:
- The number of susceptible people exposed to the fungus Coccidioides because of travel or relocation to endemic areas
- Environmental factors such as temperature and rainfall, which can affect the growth of the fungus and how much of it is circulating in the air
- The way cases are being detected and reported
More information about the increase in cases in California during 2016 and Arizona during 2017–2018 is published in the Morbidity and Mortality Weekly Report (MMWR).
On average, there were approximately 200 coccidioidomycosis-associated deaths each year (deaths in which coccidioidomycosis was listed as a primary or contributing cause on a death certificate) in the United States during 1999–2019, according to National Multiple Cause of Death data.
Although most cases of Valley fever are not associated with outbreaks, Valley fever outbreaks linked to a common source do occasionally occur, particularly after events that disturb large amounts of soil. Past outbreaks have occurred in military trainees, 6, 7 archeological workers, 8–11 solar farm workers, 12 and in people exposed to earthquakes 13 and dust storms. 14 If you live in an area with Coccidioides in the environment, contact your local or state health department for the most up-to-date information about outbreaks.
- Valdivia L, Nix D, Wright M, Lindberg E, Fagan T, Lieberman D, et al. Coccidioidomycosis as a common cause of community-acquired pneumonia. Emerg Infect Dis. 2006 Jun;12(6):958-62.
- Chang DC, Anderson S, Wannemuehler K, Engelthaler DM, Erhart L, Sunenshine RH, et al. Testing for coccidioidomycosis among patients with community-acquired pneumonia. Emerg Infect Dis. 2008 Jul;14(7):1053-9.
- Arizona Department of Health Services – Valley Fever
- California Department of Public Health – Coccidioidomycosis (Valley Fever)
- CDC. Increase in reported coccidioidomycosis – United States, 1998-2011. MMWR 62(12);217-221.
- Crum N, Lamb C, Utz G, Amundson D, Wallace M. Coccidioidomycosis outbreak among United States Navy SEALs training in a Coccidioides immitis-endemic area—Coalinga, California. J Infect Dis. 2002 Sep 15;186(6):865-8.
- Standaert SM, Schaffner W, Galgiani JN, Pinner RW, Kaufman L, Durry E, et al. Coccidioidomycosis among visitors to a Coccidioides immitis-endemic area: an outbreak in a military reserve unit. J Infect Dis. 1995 Jun;171(6):1672-5.
- Loofbourow JC, Pappagianis D, Cooper TY. Endemic coccidioidomycosis in Northern California. An outbreak in the Capay Valley of Yolo County. Calif Medi. 1969 Jul;111(1):5-9.
- Petersen LR, Marshall SL, Barton-Dickson C, Hajjeh RA, Lindsley MD, Warnock DW, et al. Coccidioidomycosis among workers at an archeological site, northeastern Utah. Emerg Infect Dis. 2004 Apr;10(4):637-42.
- Werner SB, Pappagianis D. Coccidioidomycosis in Northern California. An outbreak among archeology students near Red Bluff. Calif Med. 1973 Sep;119(3):16-20.
- Werner SB, Pappagianis D, Heindl I, Mickel A. An epidemic of coccidioidomycosis among archeology students in northern California. N Engl J Med. 1972 Mar 9;286(10):507-12.
- Wilken JA, Sondermeyer G, Shusterman D, McNary J, Vugia DJ, McDowell A et al. Coccidioidomycosis among workers constructing solar power farms, California, USA, 2011-2014. Emerg Infect Dis. 2015 Nov;21(11):1997-2005.
- Schneider E, Hajjeh RA, Spiegel RA, Jibson RW, Harp EL, Marshall GA, et al. A coccidioidomycosis outbreak following the Northridge, Calif, earthquake. JAMA. 1997 Mar 19;277(11):904-8.
- Williams PL, Sable DL, Mendez P, Smyth LT. Symptomatic coccidioidomycosis following a severe natural dust storm. An outbreak at the Naval Air Station, Lemoore, Calif. Chest. 1979