Valley Fever (Coccidioidomycosis)

What is Valley Fever?

Valley Fever, also called coccidioidomycosis, is an infection caused by the fungus Coccidioides. The fungus lives in soil in some areas, including the southwestern United States and south-central Washington, as well as in parts of Mexico as well as Central and South America.  People and animals can get Valley Fever by breathing in spores, generally from dust or disturbed soil, in areas where the fungus is found. Most people who breathe in spores do not get sick, but some people develop mild or severe forms of the disease. 

Where is the fungus found?

Coccidioides lives in dust and soil in areas of low rainfall, high summer temperatures, and moderate winter temperatures. In the United States, Coccidioides lives in Arizona, California, Nevada, New Mexico, Texas, Utah, and in south-central Washington. Coccidioides is particularly common in Arizona and Central California. See maps of where Coccidioides is estimated to live on the CDC's website

Where is Coccidioides found in Washington?

Coccidioides immitis has been found in soils of south-central Washington. However, the extent of the locations where the fungus may be in Washington is not fully known and is still under investigation. The Department of Health has reports of people who were likely exposed to Valley Fever in Yakima, Benton, Franklin, Walla Walla, and Spokane counties. Identified animal infections include likely exposure in Yakima, Benton, Franklin, Walla Walla, Asotin, and Adams counties. Environmental sampling efforts have found the fungus in soil from Benton, Kittitas, and Yakima counties; limited sampling has been done in other Washington counties, so the full geographic range is still undefined. Another type of the fungus, Coccidioides posadasii, has never been found in Washington state.

A map of Washington state showing counties where human or animal cases were likely exposed to Coccidioides, or where Coccidioides was detected in the soil. Highlighted counties include: Kittitas, Yakima, Benton, Franklin, Adams, Walla Walla, Asotin, and Spokane

How do you get Valley Fever?

People can get Valley Fever by breathing in Coccidioides spores, generally from dust or disturbed soil, for example from activities or exposures such as construction, digging, dust storms, or earthquakes. In rare cases, fungal spores can enter the skin through a cut or wound and cause infection. Animals, including pets, are also infected in these ways. Valley Fever does not generally spread from person to person or from animals to people, with rare exceptions due to organ transplantation or wound contact.

What are the symptoms of Valley Fever?

About 6 out of 10 people who are infected with the fungus will never have symptoms. Other people may have mild symptoms that usually go away on their own after weeks to months. If you think you may have been exposed to Valley Fever and experience consistent symptoms, contact your healthcare provider for evaluation and possible medication.

Symptoms of Valley Fever include:

  • Fatigue (tiredness)
  • Cough
  • Fever
  • Shortness of breath
  • Headache
  • Night sweats
  • Muscle aches or joint pain
  • Rash
  • In rare cases, the spores get into a person's skin through a cut, wound, or splinter and cause a skin infection

Can Valley Fever be serious?

Up to 1 out of 10 people who experience symptoms of Valley Fever develop serious or long-term problems in their lungs. In even fewer people about—about 1 out of 100—the infection spreads from the lungs to other parts of the body, such as the central nervous system (brain and spinal cord), skin, or bones and joints.

How soon do symptoms appear?

Symptoms usually appear one to three weeks after exposure to the fungus. However, in some people who are not treated for the infection or who experience a change to their immune system, the infection and symptoms can come back months to years after the time of the first infection.

Who is at risk?

Anyone who lives in or travels to areas where Coccidioides is present in the environment can get Valley Fever. Valley Fever is most common in adults aged 60 and older but can affect people of any age. Those at higher risk for severe illness include people with weakened immune systems, pregnant people, people who have diabetes, and people taking chronic corticosteroid therapy. Data also suggest that risk of Valley Fever infection may be greater for people of American Indian or Alaska Native descent, and the risk of severe disease may be greater among people who are Black or Filipino.

What can I do to prevent Valley Fever?

It's very difficult to avoid breathing in Coccidioides spores in areas where it's common in the environment. People who live in these areas can try to avoid spending time in dusty places, close windows and doors to prevent dust accumulation, and use air filtration in homes and vehicles. People who are at risk for severe disease should avoid areas with lots of dust, such as construction or excavation sites, or wear an N95 respirator if dust cannot be avoided. Be alert for symptoms and consult a healthcare provider for early diagnosis and treatment.

What is being done about Valley Fever?

The Department of Health is working with local public health partners, healthcare providers, and veterinarians to raise awareness that Valley Fever can be acquired in Washington. Healthcare providers should report any suspected cases to public health officials. Reporting cases helps public health officials identify and investigate where the fungus lives and keep track of the number of cases over time. Veterinarians should report any suspected cases to the Washington State Department of Agriculture.

How will climate change impact the Coccidioides fungus?

The Coccidioides fungus lives and grows in areas of low rainfall and high temperatures. Because this is an environmental fungus living and growing in soil, its ability to survive and thrive in different areas will change with changing environments. Factors that affect the ability of Coccidioides to live and grow are complex and include climate, soil conditions, and the presence of other species in the soil and environment. Because of this complexity, it is not simple to predict where and how Coccidioides growth areas will change. As we see the climate change to higher temperatures and lower rainfall, we expect potentially increasing habitat areas. Climatological experts in Washington anticipate a future with higher temperatures, continued glacier retreat and reduced mountain snowpack, and earlier seasonal snowmelt and peak stream flows, leading to water scarcity (drought). More work is needed to understand how changes in drought risk may influence health risks such as Valley fever. Currently available models predict expansion of Coccidioides habitat throughout Eastern Washington. If these models are correct, we may expect to see increasing numbers of people at risk of Valley fever exposure in Washington state.


For Public Health Partners

For Public