Causes of valley fever (coccidioidomycosis)

Learn about the causes of valley fever, how it is spread and where it is found.

On this page

What causes valley fever?

Valley fever is an infection caused by a fungus found in the soil called Coccidioides.

Valley fever should not be confused with Rift Valley fever.

How is valley fever spread?

You can get valley fever when you breathe in Coccidiodes fungal spores, which cannot be seen by the human eye.

Coccidioides fungi can be found in the dust and soil of:

  • some areas of the Southwestern U.S., including:
    • Arizona
    • California
    • Nevada
    • New Mexico
    • Texas
    • Utah
  • south-central Washington State in the U.S.
  • Mexico
  • Central America
  • South America

Coccidioides fungal spores reach the air when the soil is disrupted during:

  • farming
  • construction
  • wind activity, including dust storms
  • landscaping
  • gardening
  • any digging, such as for fossils or bones
  • recreational activities, such as dirt biking
  • earthquakes

In rare cases, valley fever can be spread through broken skin.

Valley fever is not contagious. It is not spread from person to person.

Report a problem or mistake on this page
Please select all that apply:

Thank you for your help!

You will not receive a reply. For enquiries, contact us.

Date modified: