Valley fever is an infection caused by the fungus Coccidioides. The scientific name for Valley fever is “coccidioidomycosis,” and it’s also sometimes called “San Joaquin Valley fever” or “desert rheumatism.” The term “Valley fever” usually refers to Coccidioides infection in the lungs, but the infection can spread to other parts of the body in severe cases (this is called “disseminated coccidioidomycosis”).

The fungus is known to live in the soil in the southwestern United States and parts of Mexico and Central and South America. The fungus was also recently found in south-central Washington. People can get Valley fever by breathing in the microscopic fungal spores from the air in these areas.

Most people who breathe in the spores don’t get sick, but some people do. Usually, people who get sick with Valley fever will get better on their own within weeks to months, but some people will need antifungal medication. Certain groups of people are at higher risk for developing the severe forms of the infection, and these people typically need antifungal treatment. It’s difficult to prevent exposure to Coccidioides in areas where it’s common in the environment, but people who are at higher risk for severe Valley fever should try to avoid breathing in large amounts of dust if they’re in these areas.

What You Need to Know

• Valley fever is a serious, costly illness.
• The fungus that causes Valley fever is found in soil in the southwestern United States, parts of Mexico and Central America, and parts of South America. It has also been found in south-central Washington state.
• The symptoms of Valley fever can be similar to those of other respiratory illnesses.
• People who have symptoms of Valley fever and live in, work in, or have visited an area where the fungus is common should ask their doctor to test them for Valley fever.

Valley fever is a fungal lung infection that can be devastating. Learning about Valley fever can help you and your doctor recognize the symptoms early.

Valley fever is an infection caused by a fungus that lives in the soil. About 20,000 cases are reported in the United States each year, mostly from Arizona and California, and the number of cases is increasing. Valley fever can be misdiagnosed because its symptoms are similar to those of other respiratory illnesses. Here are some important things to know about Valley fever, also called coccidioidomycosis.

From Soil to Lungs

The fungus that causes Valley fever, Coccidioides, is found in soil in the southwestern United States (see map), parts of Mexico and Central America, and parts of South America. It has also been found in south-central Washington State. The fungus might also live in similar areas with hot, dry climates. People can get Valley fever by breathing in the microscopic fungus from the air in these areas. Valley fever does not spread from person to person.

Common Symptoms May Lead to Delayed Diagnosis

Many people who are exposed to the fungus never have symptoms. Other people may have symptoms that include:

• Fatigue (tiredness)
• Cough
• Fever
• Shortness of breath
• Headache
• Night sweats
• Muscle aches or joint pain
• Rash on upper body or legs

The symptoms of Valley fever can be similar to those of other respiratory illnesses, which may cause delays in diagnosis and treatment. For many people, symptoms go away within weeks or months without any treatment. But healthcare providers may prescribe antifungal medicine for some people to reduce symptoms or prevent the infection from getting worse. People who have severe lung infections or infections that have spread to other parts of the body always need antifungal treatment and may need to stay in the hospital.

People at Risk

Valley fever is a serious, costly illness

• Nearly 75% of people with Valley fever miss work or school
• As many as 40% of people who get Valley fever are hospitalized
• The average cost of a hospital stay for a person with Valley fever is almost $50,000
• About 60–80% of patients with Valley fever are given one or more rounds of antibiotics before receiving a correct diagnosis and appropriate treatment

Anyone can get Valley fever if they live in, work in, or travel to an area where the fungus lives in the environment. Valley fever can affect people of any age, but it’s most common in adults aged 60 and older. Also, certain groups of people may be at higher risk for developing the severe forms of Valley fever, such as:

• People who have weakened immune systems, which may include people who:
  • Have HIV
  • Have had an organ transplant
  • Are taking medications such as corticosteroids or tumor necrosis factor (TNF) inhibitors
• Pregnant people
• People who have diabetes
• People who are Black or Filipino

Awareness Is Key

In areas where Valley fever is common, it’s difficult to completely avoid exposure to the fungus because it is in the environment. There is no vaccine to prevent infection. That’s why knowing about Valley fever is one of the most important ways to avoid delays in diagnosis and treatment. People who have symptoms of Valley fever and live in, work in, or have visited an area where the fungus is common should ask their doctor to test them for Valley fever. Healthcare providers should be aware that Valley fever symptoms are similar to those of other respiratory illnesses and should consider testing for Valley fever in patients with pneumonia symptoms who live in or have traveled to an area where Coccidioides lives.

What CDC Is Doing

• Raising awareness. CDC, state and local health departments, and other agencies are working together to create resources and educate the public and healthcare providers about Valley fever to reduce delays in diagnosis and treatment and to improve people’s health.
• Surveillance. In many states, healthcare providers and laboratories are required to report Valley fever cases to public health authorities. Disease reporting allows government officials to monitor trends in Valley fever cases and expansion from climate change, and to examine the burden of disease, like cost.
• Advanced molecular detection. CDC has been developing new tools that make it faster and easier to detect Coccidioides, the fungus that causes Valley fever, in the environment. CDC is also using whole genome sequencing on environmental and patient samples to investigate new areas where this fungus is living and causing illness.
• Research on testing and treatment. CDC is studying new laboratory tests to diagnose Valley fever faster and is assisting other health agencies with studies to understand the best treatment for Valley fever.

Who gets Valley fever?

Anyone who lives in or travels to the southwestern United States (Arizona, California, Nevada, New Mexico, Texas, or Utah), or parts of Mexico or Central or South America can get Valley fever. Valley fever can affect people of any age, but it’s most common in adults aged 60 and older. Certain groups of people may be at higher risk for developing the severe forms of Valley fever, such as:

• People who have weakened immune systems, for example, people who:
  • Have HIV/AIDS
  • Have had an organ transplant
  • Are taking medications such as corticosteroids or TNF-inhibitors
• Pregnant women
• People who have diabetes
• People who are Black or Filipino

Is Valley fever contagious?

No. The fungus that causes Valley fever, Coccidioides, can’t spread from the lungs between people or between people and animals. However, in extremely rare instances, a wound infection with Coccidioides can spread Valley fever to someone else, or the infection can be spread through an organ transplant with an infected organ.

Traveling to an endemic area

Should I worry about Valley fever if I’m traveling to an area where the fungus is common?
The risk of getting Valley fever is low when traveling to an area where Coccidioides lives in the environment, such as the southwestern United States, Mexico, or Central or South America. Your risk for infection could increase if you will be in a very dusty setting, but even then the risk is still low. If you have questions about your risk of getting Valley fever while traveling, talk to your healthcare provider. You can also consult CDC’s Travelers’ Health Yellow Book for more information.

I’ve had it before could I get it again?

Usually not. If you’ve already had Valley fever, your immune system will most likely protect you from getting it again. Some people can have the infection come back again (a relapse) after getting better the first time, but this is very rare.

Can my pets get Valley fever?

Yes. Pets, particularly dogs, can get valley fever, but it is not contagious between animals and people. Valley fever in dogs is similar to valley fever in humans. Like humans, many dogs that are exposed to Coccidioides never get sick. Dogs that do develop symptoms often have symptoms that include coughing, lack of energy, and weight loss. If you’re concerned about your pet’s risk of getting Valley fever or if you think that your pet has Valley fever, please talk to a veterinarian.

Coccidioides at my workplace

What should I do if I think I’ve been exposed to Coccidioides at my workplace or in a laboratory?
If you think you’ve been exposed to Coccidioides at work or in a laboratory, you should contact your Occupational Health, Infection Control, Risk Management, or Safety/Security Department. If your workplace or laboratory doesn’t have these services, you should contact your local city, county, or state health department. Recommendations about what to do in the event of a laboratory exposure have been published. There is no evidence showing that antifungal medication (i.e., prophylaxis) prevents people from getting sick with Valley fever after a workplace exposure to Coccidioides. If you develop symptoms of Valley fever, contact your healthcare provider.

How can I prevent Valley fever?

It’s very difficult to avoid breathing in the fungus Coccidioides in areas where it’s common in the environment. People who live in these areas can try to avoid spending time in dusty places as much as possible. People who are at risk for severe Valley fever (such as people who have weakened immune systems, pregnant women, people who have diabetes, or people who are Black or Filipino) may be able to lower their chances of developing the infection by trying to avoid breathing in the fungal spores.

The following are some common-sense methods that may be helpful to avoid getting Valley fever. It’s important to know that although these steps are recommended, they haven’t been proven to prevent Valley fever.

• Try to avoid areas with a lot of dust like construction or excavation sites. If you can’t avoid these areas, wear an N95 respirator (a type of face mask) while you’re there.
  Click for more information about respirators.
• Stay inside during dust storms and close your windows.
• Avoid activities that involve close contact to dirt or dust, including yard work, gardening, and digging.
• Use air filtration measures indoors.
• Clean skin injuries well with soap and water to reduce the chances of developing a skin infection, especially if the wound was exposed to dirt or dust.
• Take preventive antifungal medication if your healthcare provider says you need it.

Is there a vaccine for Valley fever?

No. Currently, there is no vaccine to prevent Valley fever, but scientists have been trying to make one since the 1960s. Because people who’ve had Valley fever are usually protected from getting it again, a vaccine could make the body’s immune system think that it’s already had Valley fever, which would likely prevent a person from being able to get the infection.

Scientists have tried several different ways to make a Valley fever vaccine. When one version of the vaccine was tested on humans in the 1980s, it didn’t provide good protection, and it also caused people to develop side effects such as swelling at the injection site. Since then, scientists have been looking at ways to make a vaccine with different ingredients that will provide better protection against Valley fever and won’t cause side effects. Studies of these new vaccines are ongoing, so it’s possible that a vaccine to prevent Valley fever could become available in the future.

Workers in endemic areas exposed to dust from disturbed soil are considered to be at a higher risk for coccidioidomycosis. Examples include:

• Agricultural workers
• Archeological workers
• Construction workers
• Geologists
• Military personnel/trainees
• Wildland firefighters
• Workers in mining, gas, and oil extraction jobs

Outbreaks of work-related coccidioidomycosis have occurred in diverse work settings. These include workers digging trenches and cast and crew members at an outdoor television filming event. Clusters of infections have also been found among employees and inmates at state prisons located in endemic areas.

Where does Coccidioides live?

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

These maps show CDC’s current estimate of where the fungi that cause coccidioidomycosis (Valley fever) live in the environment. These fungi are not distributed evenly in the shaded areas, might not be present everywhere in the shaded areas, and can also be outside the shaded areas. Darker shading shows areas where Coccidioides is more likely to live. Diagonal shading shows the potential range of Coccidioides.

Life Cycle of Coccidioides

Coccidioides spores circulate in the air after contaminated soil and dust are disturbed by humans, animals, or the weather. The spores are too small to see without a microscope. When people breathe in the spores, they are at risk for developing Valley fever. After the spores enter the lungs, the person’s body temperature allows the spores to change shape and grow into spherules. When the spherules get large enough, they break open and releases smaller pieces (called endospores) which can then potentially spread within the lungs or to other organs and grow into new spherules.

Uncommon sources of Valley fever

The most common way for someone to get Valley fever is by inhaling Coccidioides spores that are in the air. In extremely rare cases, people can get the infection from other sources, such as:

• From an organ transplant if the organ donor had Valley fever
• From inhaling spores from a wound infected with Coccidioides
• From contact with objects (such as rocks or shoes) that have been contaminated with Coccidioides

Testing Soil

I’m worried that Coccidioides is in the soil near my home. Can someone test the soil to find out if the fungus is there?
No, in this situation, testing soil for Coccidioides isn’t likely to be useful because the fungus is thought to be common in the soil in certain areas. A soil sample that tests positive for Coccidioides doesn’t necessarily mean that the soil will release the fungus into the air and cause infection. Also, there are no commercially-available tests to detect Coccidioides in soil. Testing soil for Coccidioides is currently only done for scientific research.

Testing soil for research
Scientists sometimes test soil or other environmental samples for Coccidioides to understand more about its habitat and how weather or climate patterns may affect its growth. The available methods to detect Coccidioides in the soil don’t always detect Coccidioides spores even if they are present. However, new tests are being developed so that researchers can better detect Coccidioides in the environment.

Valley Fever and the weather

Scientists continue to study how weather and climate patterns affect the habitat of the fungus that causes Valley fever. Coccidioides is thought to grow best in soil after heavy rainfall and then disperse into the air most effectively during hot, dry conditions. For example, hot and dry weather conditions have been shown to correlate with an increase in the number of Valley fever cases in Arizona and in California (but to a lesser extent). The ways in which climate change may be affecting the number of Valley fever infections, as well as the geographic range of Coccidioides, isn’t known yet, but is a subject for further research.

Geographic range of Valley fever expands to Washington State

Scientists believed that Coccidioides only lived in the Southwestern United States and parts of Latin America until discovering it in south-central Washington in 2013 after several residents developed Valley fever without recent travel to areas where the fungus is known to live. Samples from one patient and soil from the suspected exposure site were analyzed using a laboratory technique called whole genome sequencing and were found to be identical, proving that the infection was acquired in Washington.

After this discovery, many unanswered questions remain: How widespread is Coccidioides in Washington? How did it get there? How long has it been living there? Information about where a person was most likely infected with Valley fever, how strains are related, and which areas could pose a risk is essential for raising awareness about the disease among public health officials, healthcare providers, and the public. CDC is working with state and local public health officials and other agencies to better understand where the fungus lives so that healthcare providers and the public can be aware of the risk for Valley fever

The fungus that causes Valley fever lives in the soil in the southwestern United States, south-central Washington State, and parts of Mexico and Central and South America. The maps on this page show the following topics:

• Approximate areas where we know or suspect the fungus lives
• Places where Valley fever outbreaks have happened
• Cases of Valley fever detected by public health surveillance

Scientists are still learning about where the fungus that causes Valley fever can be found.

Estimated areas with coccidioidomycosis (Valley fever) in the United States

Estimated areas with coccidioidomycosis (Valley fever) worldwide

Approximate areas with Valley fever fungus

These maps show the approximate areas where we know or suspect the fungus that causes Valley fever lives. These are considered endemic areas for Coccidioides, the fungus that causes Valley fever. Much of what is known about where the fungus lives in the southwestern United States is based on skin testing studies performed in the late 1940s and early 1950s. The U.S. map also shows the locations of several outbreaks and locations of Valley fever cases acquired outside of the areas identified by those studies. Coccidioides might also live in similar areas with hot, dry climates that are not shaded on the map.

These maps show CDC’s current estimate of where the fungi that cause coccidioidomycosis (Valley fever) live in the environment. These fungi are not distributed evenly in the shaded areas, might not be present everywhere in the shaded areas, and can also be outside the shaded areas. Darker shading shows areas where Coccidioides is more likely to live. Diagonal shading shows the potential range of Coccidioides.

Valley fever outbreaks

Most cases of Valley fever are not part of an outbreak. However, Valley fever outbreaks linked to a common source do occasionally occur, particularly after events that disturb large amounts of soil. This map shows the locations of 40 Valley fever outbreaks that happened during 1940–2015. Some of these outbreaks happened in places where scientists did not expect the fungus to live. Investigating Valley fever outbreaks helps public health officials understand:

• Where the fungus lives,
• Activities that may make someone more likely to get Valley fever, and
• Groups of people more likely to get Valley fever

Many people who are exposed to the fungus Coccidioides never have symptoms. Other people may have symptoms that go away on their own after weeks to months. If your symptoms last for more than a week, contact your healthcare provider.

Symptoms of Valley fever include:

• Fatigue (tiredness)
• Cough
• Fever
• Shortness of breath
• Headache
• Night sweats
• Muscle aches or joint pain
• Rash on upper body or legs

In extremely rare cases, the fungal spores can enter the skin through a cut, wound, or splinter and cause a skin infection.

How soon do the symptoms appear?
Symptoms of Valley fever may appear between 1 and 3 weeks after a person breathes in the fungal spores.

How long do the symptoms last?
The symptoms of Valley fever usually last for a few weeks to a few months. However, some patients have symptoms that last longer than this, especially if the infection becomes severe.

Severe Valley fever
Approximately 5 to 10% of people who get Valley fever will develop serious or long-term problems in their lungs. In an even smaller percent of people (about 1%), 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 is Valley fever diagnosed?

Healthcare providers rely on your medical and travel history, symptoms, physical examinations, and laboratory tests to diagnose Valley fever. The most common way that healthcare providers test for Valley fever is by taking a blood sample and sending it to a laboratory to look for Coccidioides antibodies or antigens.

Healthcare providers may do imaging tests such as chest x-rays or CT scans of your lungs to look for Valley fever pneumonia. They may also perform a tissue biopsy, in which a small sample of tissue is taken from the body and examined under a microscope. Laboratories may also see if Coccidioides will grow from body fluids or tissues (this is called a culture).

Where can I get tested for Valley fever?

Any healthcare provider can order a test for Valley fever.

How long will it take to get my test results?

It depends on the type of test. Results from a blood test will usually be available in a few days. If your healthcare provider sends a sample to a laboratory to be cultured, the results could take a few days to a couple of weeks.

Skin testing

A skin test can detect whether you have developed an immune response to the fungus Coccidioides, the cause of Valley fever. This test became available again in the United States in 2014 for the first time since the late 1990s. Your healthcare provider might do this test if you have a history of Valley fever.

The test involves getting a small injection on the inside of your forearm, similar to a skin test for tuberculosis. If the test is positive, a bump will appear at the injection site. A healthcare provider must examine the injection site two days (48 hours) after the test was given to measure the size of the bump.

A positive test result means that you have an immune response to Coccidioides because of a past or current Coccidioides infection. Some people with a positive test result have been sick with Valley fever, but many people with a positive test have not had symptoms from the infection. A positive skin test generally means that you are immune to Coccidioides and will not get Valley fever in the future.

A negative skin test can mean that you have not been exposed to Coccidioides and have not had Valley fever. However, some people may not react to the skin test even though they have had a Coccidioides infection. This is called a false-negative result. False-negative results occur more commonly in people who:

• Have had a Coccidioides infection that is recent or severe
• Have a condition or illness that interferes with the skin test results
• Are taking a medication that interferes with the skin test results

For more information about skin testing for Valley fever, talk with your healthcare provider.

How is Valley fever treated?

For many people, the symptoms of Valley fever will go away within a few months without any treatment. Healthcare providers choose to prescribe antifungal medication for some people to try to reduce the severity of symptoms or prevent the infection from getting worse. Antifungal medication is typically given to people who are at higher risk for developing severe Valley fever. The treatment is usually 3 to 6 months of fluconazole or another type of antifungal medication. There are no over-the-counter medications to treat Valley fever. If you have Valley fever, you should talk to your healthcare provider about whether you need treatment. The healthcare provider who diagnoses you with Valley fever may suggest that you see other healthcare providers who specialize in treating Valley fever.

People who have severe lung infections or infections that have spread to other parts of the body always need antifungal treatment and may need to stay in the hospital. For these types of infections, the course of treatment is usually longer than 6 months. Valley fever that develops into meningitis is fatal if it’s not treated, so lifelong antifungal treatment is necessary for those cases.

If you are a healthcare provider, click here for more information about treatment.

If I have Valley fever, should I stay at home?

Valley fever isn’t contagious, so you don’t need to stay at home to avoid spreading the infection to other people. However, your healthcare provider may recommend that you rest at home to help your body fight off the infection.

Does Valley fever have any long-term effects?

Most people who have Valley fever will make a full recovery. A small percent of people develop long-term lung infections that can take several years to get better. In very severe cases of Valley fever, the nervous system can be affected and there may be long-term damage, but this is very rare.