Valley Fever Coccidioidomycosis

What is Valley Fever?

Coccidioidomycosis, also known as Valley Fever, “San Joaquin Valley fever” or “desert rheumatism”, is a fungal infection that occurs when the spores that are the reproductive form of the fungus Coccidioides immitis enter the body through the lungs. Most of these infections (60%) develop little or no symptoms and heal completely without need for specific treatment. Rarely (less than 1%), the infection may spread from the lungs through the bloodstream to involve other organs. This form of Valley Fever is known as disseminated coccidioidomycosis and is a more severe disease. People over 60 years of age are at higher risk of developing a more serious form of this infection.

How do you get Valley Fever?

The fungus that causes Valley Fever lives in dust and soil in the southwestern United States and parts of Mexico and Central and South America. People can get infected by the fungus when they breathe in the microscopic fungal spores from the air when the soil is disturbed, especially during dry periods.

Susceptibility and Resistance

Anyone is susceptible to Valley Fever. Certain people are more likely to develop more severe forms of Valley Fever, including people who have weakened immune systems (such as those with HIV/AIDS, who have had an organ transplant, and who are taking medications like corticosteroids), pregnant women, people with diabetes, and people who are Black or Filipino. Recovery from Valley Fever generally leads to lifelong immunity.

Incubation Period

The incubation period for Valley Fever is 7-28 days.

What are the Symptoms?

Most infected people (60%) do not show any symptoms. Of those that do, most develop flu-like symptoms that usually go away on their own after a few weeks. These symptoms include fatigue, cough, fever, shortness of breath, headache, night sweats, muscle and joint aches, and rash on upper body or legs. The spores can also enter through a cut or wound and cause a skin infection, but this only occurs in extremely rare cases.

A small percentage of people develop a more severe form of Valley Fever. In approximately 5 to 10% of people, the infection can cause serious and long-term lung problems. In about 1% of people, the infection spreads to other parts of the body, such as the central nervous system (brain and spinal cord), skin, or bones and joints.

Preventative Measures

It is difficult to prevent inhalation of the fungal spores in areas where they live in the soil and dust, but the risk of getting Valley Fever is low, even in dusty areas. People who are at increased risk may lower their chances of developing the infection by attempting to avoid breathing in dust in endemic areas. There are some simple things travelers can do to avoid inhaling the dust, such as avoiding areas with lots of dust or wearing an N95 respirator in these areas (construction or excavation sites), staying inside and closing the windows during dust storms, avoiding activities that have close contact with dirt or dust (gardening or digging), using air filtration indoors, cleaning skin injuries well with soap and water, and taking preventive antifungal medication if recommended by your healthcare provider.


In most people with Valley Fever, the symptoms are not severe and will go away within a few weeks without the need for treatment. Some healthcare providers may prescribe antifungal medication to reduce symptoms or prevent them from getting worse, particularly for people who are at high risk of developing a more severe infection.

Where Does It Commonly Occur?

The Coccidioides fungi live in the dust and soil in some areas in the southwestern United States, Mexico, and Central and South America. In the United States, the fungi live in Arizona, California, Nevada, New Mexico, Texas, and Utah. It was also recently found in south-central Washington State.