ConditionInfections
Valley Fever (Coccidioidomycosis)
Valley fever, or coccidioidomycosis, is a lung infection caused by breathing in spores of Coccidioides, a fungus that lives in soil in the southwestern US (especially Arizona and California's Central Valley), parts of Washington, Mexico and Central and South America. Most people have no symptoms or a flu-like illness with cough, fever, fatigue, chest pain and sometimes a rash, which clears in weeks to months. A small number develop severe or spreading infection. It is not contagious between people. Testing matters because it is often mistaken for pneumonia.
Also called: Coccidioidomycosis, cocci, San Joaquin Valley fever, desert rheumatism
At a glance
- Cause
- Breathing in spores of the soil fungus Coccidioides.
- Where
- Southwestern US, especially Arizona and California, plus parts of Washington, Mexico and Latin America.
- Symptoms
- Often none. Otherwise fatigue, cough, fever, chest pain, night sweats, joint aches, red bumps on the shins.
- Higher risk of severe disease
- Weakened immunity, pregnancy, diabetes, and people of Black or Filipino descent.
- Treatment
- Many recover without medicine. Antifungals such as fluconazole for moderate, severe or spreading infection.
When to get help
Call 911 or go to the ER
- Severe shortness of breath, chest pain, or confusion
- Severe headache with stiff neck, vomiting or confusion (possible meningitis)
See a doctor within a day or two
- Cough, fever and fatigue lasting more than a week after living in or visiting a valley fever area, especially if antibiotics have not helped
- Valley fever symptoms in pregnancy, or with diabetes or a weakened immune system
- New bone pain, skin sores or swollen joints during or after valley fever
Book a routine appointment
- Fatigue that has not improved after several weeks of known valley fever
- Painful red bumps on the shins with joint aches after desert travel
Usually safe to manage at home
- Diagnosed mild valley fever that is gradually improving: rest, fluids and follow-up as advised
How valley fever spreads
Coccidioides lives in desert soil. When soil is disturbed by wind, dust storms, construction, farming, digging or off-road driving, spores become airborne and can be inhaled. Infection usually happens through the lungs.
- It does not spread from person to person, or between people and pets.
- Dogs can get valley fever too, from the same soil exposure.
- Infection usually gives lifelong immunity.
Symptoms
About 60 percent of infected people have no symptoms. In others, symptoms begin 1 to 3 weeks after exposure:
- extreme tiredness, often the most lasting symptom
- cough
- fever
- shortness of breath
- chest pain
- headache
- night sweats
- muscle and joint aches ("desert rheumatism")
- a rash: red, tender bumps on the shins (erythema nodosum) or a widespread rash on the upper body
Symptoms usually improve over weeks to months. Fatigue can last longer.
Forms of valley fever
| Form | What happens |
|---|---|
| Acute (primary) | Flu-like or pneumonia-like illness that resolves |
| Chronic pulmonary | Lasting lung infection, nodules or cavities, in a small number |
| Disseminated | Spread beyond the lungs to skin, bones, joints or the brain lining (meningitis). Rare but serious |
Who is at higher risk of severe disease
- weakened immune system: HIV, organ transplant, cancer treatment, high-dose steroids, TNF inhibitors
- pregnancy, especially in the third trimester
- diabetes
- people of Black or Filipino descent
- older adults
People who work outdoors in endemic areas, such as construction, farming, archaeology and military training, have more exposure.
Diagnosis
Valley fever is often misdiagnosed as bacterial pneumonia, so testing matters for anyone with lung symptoms who lives in or has visited an endemic area.
- blood antibody tests (EIA, immunodiffusion, complement fixation): the main tests. Early tests can be negative, so repeat testing may be needed
- chest X-ray or CT to look for pneumonia, nodules, cavities or enlarged lymph nodes
- culture or tissue samples from sputum, fluid or biopsy
- lumbar puncture if meningitis is suspected
Treatment
Mild cases
Many healthy people recover without antifungal medicine. Doctors monitor symptoms and repeat blood tests and chest X-rays. Rest and fluids help.
Antifungal medicine
Treatment is recommended for people with moderate to severe symptoms, prolonged illness, high risk, or spread beyond the lungs:
- fluconazole or itraconazole by mouth, usually for 3 to 6 months or longer
- amphotericin B for severe or rapidly progressive disease
- lifelong fluconazole for valley fever meningitis
- pregnancy: azole antifungals can harm the developing baby, especially in the first trimester, so amphotericin B is often used instead
Surgery may be needed for lung cavities or infected bones and joints.
Prevention
There is no vaccine. In endemic areas:
- avoid dusty areas and dust storms when possible
- stay inside with windows closed during dust storms
- wet soil before digging, and wear a fitted N95 respirator during dusty work
- people at high risk should take extra care with soil-disturbing activities
Frequently asked questions
What are the first signs of valley fever?
The first signs are usually fatigue, cough, fever, chest pain and shortness of breath, 1 to 3 weeks after breathing in the fungus. Some people get night sweats, joint aches or a rash with tender red bumps on the shins. Many infected people have no symptoms.
Is valley fever contagious?
No. Valley fever cannot spread from person to person or from pets to people. It is caught only by breathing in fungal spores from soil and dust in areas where the fungus lives.
How is valley fever treated?
Many mild cases resolve without medicine and are monitored. People with moderate or severe symptoms, those at higher risk, and those with spread beyond the lungs are treated with antifungal medicines such as fluconazole for months, or amphotericin B for severe disease.
How long does valley fever last?
Most acute cases improve within a few weeks to a few months, though tiredness can linger longer. Chronic lung infection or spread to other parts of the body can require many months or lifelong treatment.
Sources
This guide was written from current patient and clinical guidance, including:
- CDC: Valley Fever (Coccidioidomycosis)
- Infectious Diseases Society of America: Clinical Practice Guideline for the Treatment of Coccidioidomycosis
- Valley Fever Center for Excellence (University of Arizona): Patient information
- MedlinePlus: Valley fever
- California Department of Public Health: Valley fever