Valley fever


Valley fever is a fungal infection caused by coccidioides (kok-sid-e-OY-deze) organisms. It can cause signs and symptoms such as a fever, cough and tiredness.

Two coccidioides fungi species cause valley fever. These fungi are commonly found in soil in specific regions. The fungi's spores can be stirred into the air by anything that disrupts the soil, such as farming, construction and wind.

People can then breathe the fungi into their lungs. The fungi can cause valley fever, also known as acute coccidioidomycosis (kok-sid-e-oy-doh-my-KOH-sis). Mild cases of valley fever usually resolve on their own. In more-severe cases, doctors treat the infection with antifungal medications.


Valley fever is the initial form of coccidioidomycosis infection. This initial, acute illness can develop into a more serious disease, including chronic and disseminated coccidioidomycosis.

Acute coccidioidomycosis (valley fever)

The initial, or acute, form of coccidioidomycosis is often mild, with few or no symptoms. Signs and symptoms occur one to three weeks after exposure. They tend to be similar to flu symptoms. Symptoms can range from minor to severe, including:

  • Fever
  • Cough
  • Tiredness
  • Shortness of breath
  • Headache
  • Chills
  • Night sweats
  • Joint aches and muscle soreness
  • Red, spotty rash, mainly on lower legs but sometimes on the chest, arms and back

If you don't become ill or have symptoms from valley fever, you may only find out you've been infected later. You may find out when you have a positive skin or blood test or when small areas of residual infection in the lungs (nodules) show up on a routine chest X-ray. The nodules typically don't cause problems, but they can look like cancer on X-rays.

If you develop symptoms, especially severe ones, the course of the disease is highly variable. It can take months to fully recover. Fatigue and joint aches can last even longer. The disease's severity depends on several factors, including your overall health and the number of fungus spores you inhale.

Chronic coccidioidomycosis

If the initial coccidioidomycosis infection doesn't completely resolve, it may progress to a chronic form of pneumonia. This complication is most common in people with weakened immune systems.

Signs and symptoms include:

  • Low-grade fever
  • Weight loss
  • Cough
  • Chest pain
  • Blood-tinged sputum (matter discharged during coughing)
  • Nodules in the lungs

Disseminated coccidioidomycosis

The most serious form of the disease, disseminated coccidioidomycosis, is uncommon. It occurs when the infection spreads (disseminates) beyond the lungs to other parts of the body. Most often these parts include the skin, bones, liver, brain, heart, and the membranes that protect the brain and spinal cord (meninges).

Signs and symptoms of disseminated disease depend on the body parts affected and may include:

  • Nodules, ulcers and skin lesions that are more serious than the rash that sometimes occurs with initial infection
  • Painful lesions in the skull, spine or other bones
  • Painful, swollen joints, especially in the knees or ankles
  • Meningitis — an infection of the membranes and fluid surrounding the brain and spinal cord

When to see a doctor

Seek medical care if you are over 60, have a weakened immune system, are pregnant, or are of Filipino or African heritage, and you develop the signs and symptoms of valley fever, especially if you:

  • Live in or have recently traveled to an area where this disease is common
  • Have symptoms that aren't improving

Be sure to tell your doctor if you've traveled to a place where valley fever is common and you have symptoms.


Valley fever is caused by a person inhaling spores of certain fungi. The fungi that cause valley fever — Coccidioides immitis or Coccidioides posadasii — live in the soil in parts of Arizona, Nevada, Utah, New Mexico, California, Texas and Washington. It's named after the San Joaquin Valley in California. The fungi can also often be found in northern Mexico and Central and South America.

Like many other fungi, coccidioides species have a complex life cycle. In the soil, they grow as a mold with long filaments that break off into airborne spores when the soil is disturbed. A person can then inhale the spores.

The spores are extremely small and can be carried far by the wind. Once inside the lungs, the spores reproduce, continuing the disease cycle.

Risk factors

Risk factors for valley fever include:

  • Environmental exposure. Anyone who inhales the spores that cause valley fever is at risk of infection. People who live in areas where the fungi are common — especially those who spend a lot of time outdoors — have a greater risk.

    Also, people who have jobs that expose them to dust are most at risk — construction, road and agricultural workers, ranchers, archaeologists, and military personnel on field exercises.

  • Race. For reasons that aren't well understood, people of Filipino and African heritage are more susceptible to developing serious fungal infections.
  • Pregnancy. Pregnant women are vulnerable to more-serious infections when they get the infection during the third trimester. New mothers are vulnerable right after their babies are born.
  • Weakened immune system. Anyone with a weakened immune system is at increased risk of serious complications. This includes people living with AIDS or those being treated with steroids, chemotherapy and anti-rejection drugs after transplant surgery. People with certain autoimmune diseases, such as rheumatoid arthritis or Crohn's disease, who are being treated with anti-tumor necrosis factor (TNF) drugs also have an increased risk of infection.
  • Diabetes. People with diabetes may have a higher risk of severe lung infections.
  • Age. Older adults are more likely to develop valley fever. This may be because their immune systems are less robust or because they have other medical conditions that affect their overall health.


Some people, especially pregnant women, people with weakened immune systems — such as those living with HIV/AIDS — and those of Filipino or African heritage are at risk of developing a more severe form of coccidioidomycosis.

Complications of coccidioidomycosis may include:

  • Severe pneumonia. Most people recover from coccidioidomycosis-related pneumonia without complications. Others, such as people of Filipino and African heritage, and those with weakened immune systems, may become seriously ill.
  • Ruptured lung nodules. A small percentage of people develop thin-walled nodules (cavities) in their lungs. Many of these eventually disappear without causing any problems, but some may rupture, causing chest pain and difficulty breathing. A ruptured lung nodule might require the placement of a tube into the space around the lungs to remove the air or surgery to repair the damage.
  • Disseminated disease. This is the most serious complication of coccidioidomycosis but it's uncommon. If the fungus spreads (disseminates) throughout the body, it can cause problems including skin ulcers, abscesses, bone lesions, severe joint pain, heart inflammation, urinary tract problems and meningitis — a potentially fatal infection of the membranes and fluid covering the brain and spinal cord.


There is no vaccine to prevent valley fever.

If you live in or visit areas where valley fever is common, take common-sense precautions, especially during the dry season following a rainy season when the chance of infection is highest.

Consider these tips:

  • Wear a mask.
  • Avoid very dusty areas, such as construction sites.
  • Stay inside during dust storms.
  • Wet the soil before digging in it, or avoiding soil if you're at higher risk of infection.
  • Keep doors and windows tightly closed.
  • Clean skin injuries with soap and water.


To diagnose valley fever, your doctor may evaluate your medical history and review your signs and symptoms. Valley fever is difficult to diagnose based on the signs and symptoms, because symptoms are usually vague and similar to those that occur in other illnesses. Even a chest X-ray can't help doctors see the difference between valley fever and other forms of lung infection such as pneumonia.

To diagnose valley fever, doctors may order one or more of the following tests:

  • Sputum smear or culture. These tests check a sample of the matter that's discharged while coughing (sputum) for the presence of coccidioides organisms.
  • Blood tests. Through a blood test, your doctor can check for antibodies against the fungus that causes valley fever.

If doctors think you may have pneumonia due to valley fever, they may also order imaging tests, such as a CT scan, MRI or chest X-ray.

If needed, doctors may remove a sample of tissue from the lungs for testing.

In some cases, doctors may do a skin test to find out if you've had valley fever in the past and have developed immunity.


Valley fever usually involves supportive care and sometimes medications.


Most people with acute valley fever don't require treatment. Still, doctors carefully monitor people with valley fever.

Antifungal medications

If symptoms don't improve, last a long time or become worse, or you're at increased risk of complications, your doctor may prescribe an antifungal medication, such as fluconazole. Antifungal medications are also used for people with chronic or disseminated disease.

The antifungal drugs fluconazole (Diflucan) or itraconazole (Sporanox, Tolsura) are generally used for all but the most serious forms of coccidioidomycosis disease.

All antifungals can have serious side effects. But these side effects usually go away once the medication is stopped. Possible side effects of fluconazole and itraconazole are nausea, vomiting, stomach pain and diarrhea. Side effects of fluconazole may be hair loss, dry skin, dry mouth and chapped lips.

More serious infection may first be treated with an intravenous antifungal medication such as amphotericin B (Abelcet, Ambisome, others).

Three newer medications — voriconazole (Vfend), posaconazole (Noxafil) isavuconazonium sulfate (Cresemba) — may also be used to treat more-serious infections.

For many people, a single bout of valley fever results in lifelong immunity. But the disease can be reactivated, or you can be reinfected if your immune system is significantly weakened.

Preparing for your appointment

Make an appointment with your doctor if you develop signs or symptoms of valley fever and are in or have recently returned from a region where this condition is common.

Here's some information to help you get ready and know what to expect from your doctor.

Information to gather in advance

  • Pre-appointment restrictions. At the time you make your appointment, ask if there are any restrictions you need to follow in the time leading up to your visit.
  • Symptom history. Write down any symptoms you've been experiencing, and for how long.
  • Recent exposure to possible sources of infection. Your doctor will be especially interested to know if you have recently traveled, and where.
  • Medical history. Make a list of your key medical information, including other conditions for which you're being treated and any medications, vitamins or supplements you're currently taking.
  • Questions to ask your doctor. Write down your questions in advance so that you can make the most of your time with your doctor.

The list below suggests questions to raise with your doctor about valley fever. Don't hesitate to ask more questions during your appointment.

  • What's the most likely cause of my symptoms?
  • What kinds of tests do I need?
  • What treatment approach do you recommend, if any?
  • I have these other health conditions. How can I best manage these conditions together?
  • If you're recommending medications, are there any possible side effects?
  • How long do you expect a full recovery to take, and will I need a follow-up appointment?
  • Am I at risk of any long-term complications from this condition?

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to talk about in-depth. Your doctor may ask:

  • What are your symptoms?
  • When did you first begin experiencing symptoms?
  • Have your symptoms gotten worse over time?
  • Have you recently traveled? Where and when?
  • Does your work or recreational activities involve spending time in dusty outdoor environments?
  • Are you pregnant?
  • Have you been diagnosed with any other medical conditions?
  • Are you currently taking any medications, including over-the-counter and prescription drugs as well as any vitamins and supplements?

Last Updated Mar 21, 2023

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