Valley Fever: Arizona's Signature Infection
The fungus that lives in the dirt and makes a living off newcomers
66%of all U.S. Valley Fever cases are in Arizona
Last reviewed: April 2026
If you live in Arizona long enough, you will either get Valley Fever or know someone who has. Caused by the Coccidioides fungus that lives in the soil of the Sonoran Desert, Valley Fever (formally called coccidioidomycosis) infects about 15,000 Arizonans each year. Most people recover without treatment. Some get seriously ill.
The fungus gets into the air when soil is disturbed by wind, construction, farming, or even a good monsoon dust storm. You breathe it in, and your lungs become the battleground. Many people mistake it for a cold or flu that just will not quit. Others never realize they had it.
Valley Fever is genuinely unique to the desert Southwest. Doctors in other parts of the country frequently miss it because they have never seen a case. If you live in Arizona and have a cough that has lasted more than a few weeks, Valley Fever should be on the list of things to test for.
How You Get It
Coccidioides lives in the top few inches of soil in arid regions, especially in central and southern Arizona. When the ground is disturbed, fungal spores (called arthroconidia) become airborne. You inhale them, and they settle in your lungs.
You cannot catch Valley Fever from another person. It is not contagious. You get it from breathing in spores from the environment. Activities that increase exposure include construction, landscaping, farming, hiking, off-roading, and anything that kicks up desert dust. Dust storms and post-monsoon drying periods are peak exposure times.
Who Is Most at Risk
Anyone who breathes Arizona air can get Valley Fever, but some people face a higher risk of severe disease. People with weakened immune systems (from HIV, organ transplants, cancer treatment, or immunosuppressive medications) are at greatest risk for disseminated (widespread) Valley Fever. Pregnant women, especially in the third trimester, face increased risk. People of African American and Filipino descent are statistically more likely to develop severe forms. Older adults and people with diabetes also face higher risk.
New arrivals to Arizona who have never been exposed to the fungus before are especially susceptible. Your immune system has no history with this organism, so the initial infection can hit harder.
Symptoms: The Flu That Will Not Leave
About 60% of people who inhale Valley Fever spores never develop symptoms. Their immune system handles it quietly. The other 40% typically develop symptoms 1-3 weeks after exposure.
Common symptoms include a cough that lasts weeks, fever, chest pain, fatigue and body aches, headache, night sweats, rash (especially on the lower legs, called erythema nodosum, or "desert bumps"), and joint pain. The symptom profile overlaps heavily with pneumonia, the flu, and COVID-19, which is why testing matters.
Testing and Diagnosis
Valley Fever is diagnosed through blood tests that look for antibodies (IgM and IgG) against Coccidioides. The most common tests are the enzyme immunoassay (EIA) and the immunodiffusion test. Results can take a few days.
A chest X-ray or CT scan may show lung nodules or infiltrates. In some cases, a doctor will order a culture or biopsy to confirm the diagnosis, especially if the disease has spread beyond the lungs. If you have a persistent cough and live in Arizona, ask your doctor to test for Valley Fever. Many providers in the Phoenix and Tucson metros test routinely, but it can still be overlooked.
Treatment
Most healthy people recover from Valley Fever without antifungal medication. Treatment focuses on rest, fluids, and monitoring. Recovery can take weeks to months, and fatigue often lingers.
Antifungal medication (fluconazole or itraconazole) is prescribed for people with severe symptoms, prolonged illness (more than 6 weeks), or risk factors for dissemination. Disseminated Valley Fever, where the infection spreads to bones, joints, skin, or the brain (meningitis), requires long-term antifungal treatment, sometimes for life.
Seek Medical Attention If You Experience
See your doctor promptly if you have a cough lasting more than 3 weeks with fever or chest pain, night sweats and unexplained weight loss, a rash on your shins that appeared after a respiratory illness, or if you are immunocompromised and develop any respiratory symptoms. Go to the emergency room if you have a severe headache with stiff neck (possible meningitis), confusion, or difficulty breathing. Disseminated Valley Fever involving the brain is life-threatening and requires immediate treatment.
Reducing Your Exposure
You cannot completely avoid Valley Fever spores in Arizona, but you can reduce your risk. Stay indoors during dust storms and close windows. Wet the ground before digging in your yard. Wear an N95 mask during construction, landscaping, or any activity that disturbs soil. Keep car windows up when driving on unpaved roads. After a monsoon, let the ground dry for a few days before extended outdoor activity.
Air purifiers with HEPA filters help reduce indoor spore counts. Landscaping with gravel or decomposed granite instead of bare soil around your home also reduces local spore exposure.
Valley Fever Awareness Checklist
- Know the symptoms: persistent cough, fever, fatigue, chest pain, rash
- Ask your doctor to test for Valley Fever if you have a cough lasting 3+ weeks
- Stay inside and close windows during dust storms
- Wear an N95 mask for outdoor digging, construction, or landscaping
- Tell out-of-state doctors about your Arizona residency if you get sick while traveling
- If you are immunocompromised, discuss Valley Fever prevention with your doctor
- Report confirmed cases to the Maricopa County or state health department
Frequently Asked Questions
Can you get Valley Fever more than once?
Generally, people who recover from Valley Fever develop lifelong immunity. Reinfection is rare in healthy individuals. People who are immunocompromised may experience reactivation of a previous infection rather than a new one.
Can my dog get Valley Fever?
Yes. Dogs are even more susceptible than humans because they sniff close to the ground. Symptoms in dogs include coughing, lethargy, lameness, and swollen joints. If your dog shows these signs, see a veterinarian. Dog Valley Fever is treated with the same antifungal medications used in humans.
Is there a vaccine for Valley Fever?
Not yet. Researchers at the University of Arizona and other institutions have been working on a Valley Fever vaccine for years. Clinical trials are underway for a canine vaccine, and a human vaccine is in earlier stages of development.
Does Valley Fever show up on a COVID test?
No. Valley Fever and COVID-19 are caused by completely different organisms (a fungus vs. a virus), and their tests are different. However, the symptoms overlap significantly. If you test negative for COVID but your symptoms persist, ask about Valley Fever testing.
How long does it take to recover from Valley Fever?
Mild cases typically resolve in a few weeks to a few months. Fatigue can linger for 6 months or longer. Severe or disseminated cases may require years of treatment. Most healthy people make a full recovery.