Reported Cases of Valley Fever

Key points

  • Valley fever is most common in California and Arizona.
  • Each year around 20,000 cases of Valley fever are reported in the United States.
  • It is underdiagnosed; thousands of cases are not reported.
  • The estimated true burden is around 206,000-360,000 cases per year, 10-18 times more than reported.
This map shows the average incidence of reported Valley fever per 100,000 people, by county, during 2011–2017.

Public health surveillance

Valley fever (coccidioidomycosis) is reportable in select states. Health departments collect and send information on cases to CDC through the National Notifiable Diseases Surveillance System (NNDSS).

Resource

Weekly and annual data are available through NNDSS.

Valley fever is most common in the southwestern United States. Check with your local, state, or territorial health department for more information about disease reporting requirements in your area.

Rates and trends of reported cases

Cases reported in 2023

21,037
In 2023, states reported a total of 21,037 cases of Valley fever to CDC. *
  • Roughly 20,000 cases are reported to CDC each year.
  • Rates are highest among people 60 years and older.
  • Causes around 15% to 30% of community-acquired pneumonias in Phoenix and Tucson metropolitan areas.

*Provisional data

Reported Valley fever cases, 1998-2022

Data table

Cases reported each year by state: Arizona, California, Nevada/New Mexico/Utah, and other states.

The numbers reported here represent finalized annual NNDSS data. Numbers for 2023 are provisional. Case counts reported by individual states might differ slightly from those reported here. This is because of differences in the timing of reports or surveillance methods.

 Number of reported coccidioidomycosis cases 1998-2019
Year Arizona California Nevada, New Mexico, and Utah Other states Total
1998 1,474 719 72 6 2,271
1999 1,812 939 55 20 2,826
2000 1,917 840 67 41 2,865
2001 2,301 1,538 63 30 3,932
2002 3,133 1,727 64 44 4,968
2003 2,695 2,091 55 29 4,870
2004 3,667 2,641 110 31 6,449
2005 3,516 2,885 108 33 6,542
2006 5,535 3,131 140 111 8,917
2007 4,832 2,991 163 135 8,121
2008 4,768 2,597 99 59 7,523
2009 10,233 2,488 147 58 12,926
2010 11,883 4,622 159 129 16,793
2011 16,467 5,697 237 233 22,634
2012 12,920 4,431 211 240 17,802
2013 5,861 3,272 162 143 9,438
2014 5,624 2,243 156 209 8,232
2015 7,622 3,053 198 199 11,072
2016 6,101 5,358 151 219 11,829
2017 6,885 6,925 279 275 14,364
2018 7,478 7,546 276 311 15,611
2019 10,359 9,004 350 290 20,003
2020 11,527 7,090 294 309 19,220
2021 11,489 8,058 258 397 20,202
2022 9,515 7,459 284 354 17,612
2023 10,990 9,060 566 555 21,171

Death rates

On average, there were approximately 200 coccidioidomycosis-associated deaths reported each year from 1999-2023. Deaths are considered coccidioidomycosis-associated anytime coccidioidomycosis is listed as a primary or contributing cause on a death certificate.

Map of reported cases

Average incidence of reported Valley fever per 100,000 people, by county, during 2011–2017

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This map shows the average incidence of reported Valley fever per 100,000 people, by county, during 2011–2017.
Average incidence of reported Valley fever, 2011–2017.

Note:

  • Rates in counties with <5 reported cases might not be reliable.
  • Cases are classified by county of residence.
  • Cases infected while traveling are attributed to county of residence.

Estimated true burden

Valley fever is underestimated due to misdiagnoses, underdiagnoses, and lack of care seeking. CDC scientists developed a model accounting for these factors. The model was used to estimate the true number of cases, hospitalizations, and deaths— collectively referred to as the burden.

Estimated true burden of Valley fever

  • 206,000–360,000 symptomatic cases; 10-18 times more cases than reported.
  • 18,000–28,000 hospitalizations; 2-3 times more than found in national data.
  • 700–1,100 deaths; 5-6 times more deaths than reported.


Read more about estimates

Research on year-to-year changes

The reasons for the year-to-year changes in the number of reported Valley fever cases are not entirely known.

Factors that could explain these changes include:

  • The number of people who travel or relocate to endemic areas.
  • Environmental factors such as temperature and rainfall.
    • These affect the growth and circulation of the fungus.
  • The way cases are being detected and reported.

Find more information about the increase in cases in California during 2016 and Arizona during 2017–2018.

For Everyone Areas with Valley Fever
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