Facts and Stats about Valley Fever

Key points

  • Valley fever is a reportable disease in some states.
  • States usually report a total of 10,000 - 20,000 cases of Valley fever yearly in the United States.
  • Most cases occur in California and Arizona among people over 60 years.
  • Thousands of cases are not reported, and many are never diagnosed or misdiagnosed.
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 typically seen the southwestern United States. Check with your local, state, or territorial health department for more information about disease reporting requirements and procedures in your area.

Keep Reading: Areas with Valley Fever

Estimated rates and trends

  • Roughly 10,000 - 20,000 cases of are reported to CDC each year.
  • Most cases are among people who live in Arizona and California.
  • Rates are highest among people 60 years and older.

In 2022, states reported a total of 17,612 cases of Valley fever to CDC.

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 2022 are finalized but not yet published on CDC Wonder. 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 Non-endemic states Other states Total
1998 1,474 719 72 6 78 2,271
1999 1,812 939 55 20 75 2,826
2000 1,917 840 67 41 108 2,865
2001 2,301 1,538 63 30 93 3,932
2002 3,133 1,727 64 44 108 4,968
2003 2,695 2,091 55 29 84 4,870
2004 3,667 2,641 110 31 141 6,449
2005 3,516 2,885 108 33 141 6,542
2006 5,535 3,131 140 111 251 8,917
2007 4,832 2,991 163 135 298 8,121
2008 4,768 2,597 99 59 158 7,523
2009 10,233 2,488 147 58 205 12,926
2010 11,883 4,622 159 129 288 16,793
2011 16,467 5,697 237 233 470 22,634
2012 12,920 4,431 211 240 451 17,802
2013 5,861 3,272 162 143 305 9,438
2014 5,624 2,243 156 209 365 8,232
2015 7,622 3,053 198 199 397 11,072
2016 6,101 5,358 151 219 370 11,829
2017 6,885 6,925 279 275 554 14,364
2018 7,478 7,546 276 311 587 15,611
2019 10,359 9,004 350 290 640 20,003
2020 11,527 7,090 294 309 603 19,220
2021 11,489 8,058 258 397 655 20,202
2022 9,515 7,459 284 354 638 17,612

Death rates

On average, there were approximately 200 coccidioidomycosis-associated deaths each year from 1999-2021. 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.

Limitations

The number of Valley fever cases reported likely underestimates the true number of cases. Tens of thousands more illnesses likely occur. Cases frequently are never diagnosed or misdiagnosed because many patients are not tested for Valley fever.

Valley fever causes around 15% to 30% of community-acquired pneumonias in Pheonix and Tuscon metropolitan areas, yet testing remains low.

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.

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Content Source:
National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)