Optimized, efficient answers

Streamlined, patient-focused testing

Valley fever, or coccidioidomycosis, is an infection caused by Coccidioides species, a dimorphic fungal pathogen. Coccidioides species are primarily found in the arid soils of the southwestern United States and parts of Mexico, Central America, and South America, although the geographic range is expanding in response to climate change.1 Infection occurs following inhalation of Coccidioides spores. While most infected individuals will not exhibit symptoms, certain individuals, including those who are immunocompromised, are at significantly higher risk for becoming severely ill.

Confirming Valley fever typically requires a multi-pronged approach, including fungal culture, molecular testing, and serologic assessment for antibodies developed against the organism.

While the reference method for Coccidioides serologic testing includes complement fixation (CF) and immunodiffusion (ID) assays, these assays are technically challenging to perform, require manual manipulation and interpretation, and have a turnaround time to results of 48-72 hours. 2

To optimize testing, Mayo Clinic Laboratories offers an upfront, screening enzyme-linked immunosorbent assay (ELISA) to detect Coccidioides antibodies prior to testing by Coccidioides CF/ID. Samples that result as reactive by ELISA are subsequently reflexed for confirmatory, CF/ID testing. This enables:

  • Faster turnaround of negative results by ELISA
  • Lower overall cost for samples with initial negative results

Key testing

COXIS | Coccidioides Antibody Screen with Reflex, Serum*

  • Uses an ELISA to screen for Coccidioides antibodies with a reflex to complement fixation/immunodiffusion if results are reactive.
  • Offers increased sensitivity (ELISA) and specificity (CF/ID) for diagnostic certainty.
  • Negative results reported in 24 hours.
  • Lower testing costs when screening using the ELISA.
    • The majority of test results are negative and require no further testing.
  • Support testing stewardship through improved test utilization.

*If reactive, will reflex to:

By the numbers


cases of Valley fever reported to the Centers for Disease Control and Prevention in 20193


of individuals with coccidioidomycosis are asymptomatic4


annual deaths associated with coccidioidomycosis3

Additional testing

A new approach to diagnosing Valley fever

In this "Hot Topic," Elitza Theel, Ph.D., shares the recommended approach to serologic testing for assessment or infection with coccidioides.

Learn how to order these evaluations at your institution.


  1. Gorris M., Treseder K., Zender C., Randerson J. Expandion of Coccidiomycosis Endemic Regions in the United States in Response to Climate Change. GeoHealth, 3, 308-327. https:///doi.org/10.1029/2019GH000209
  2. McHardy I., Barker B., thompson G., Review of Clinical and Laboaratory Diagnostics for Coccidiomycosis. Journal of Clinical Microbiology. March 2023.
  3. Valley Fever (Coccidiomycosis) Statistics. Fungal Diseases. Centers for Disease Control and Prevention.https://www.cdc.gov/fungal/diseases/coccidioidomycosis/statistics.html. Page reviewed July 2022. Accessed January 2023.
  4. Crum NF. Coccidioidomycosis: A Contemporary Review. Infect Dis Ther. 2022;11(2):713-742. doi:10.1007/s40121-022-00606-y