Topic Overview

What is valley fever?

Valley fever is a disease caused by a fungus that gets into your body through your lungs. It can make you feel like you have a cold or influenza ( flu) and may cause a rash. Most people get better without treatment.

But if your body's natural defence system (immune system) is weak, valley fever can be deadly. In rare cases it can be deadly even for people with a normal immune system. Valley fever can spread from your lungs to other parts of your body. Those at higher risk for severe illness include pregnant women, people who have HIV infection, people who take medicines that weaken the immune system, and people who have diabetes. Filipinos, people of African or Hispanic descent, and Indigenous peoples also have a higher risk of dying from valley fever.^{footnote 1}

Valley fever occurs mainly in dry desert areas of the southwestern United States, central California, and Mexico. It also occurs in dry areas of Central and South America.

Valley fever is also called desert fever, San Joaquin Valley fever, coccidioidomycosis, and desert rheumatism.

What causes valley fever?

You can get valley fever if you breathe in the fungus ( Coccidioides immitis) that causes the disease.

The fungus grows in the soil. It gets into the air when the ground is broken and the dirt and dust spread into the air. People with jobs that require digging in the soil have the greatest chance of getting valley fever. This includes people who work on farms, in construction, and in archeology or paleontology. People who ride bikes or drive all-terrain vehicles (ATVs) in the desert also have a higher chance of getting it. Dust storms can spread the fungus into the air, so other people can also get valley fever.

Valley fever is not contagious. You cannot get it from another person or from animals.

After getting better, most people will not get valley fever again. This is called being immune. But valley fever can come back again in people who have weak immune systems and can't fight infection. This includes people who have HIV, are taking medicine that suppresses the immune system (such as prednisone or methotrexate), or have had an organ transplant.

What are the symptoms?

Most people don't have any symptoms, or they have only very mild symptoms. If you do have symptoms, you may feel like you have a cold or the flu. You may have a fever, chills, chest pain, a dry cough, and a rash.

The time from contact with the fungus until symptoms start is usually 1 to 3 weeks. This is called the incubation period.

In rare cases, valley fever can spread to the skin, bones, lymph nodes, and organs. It can lead to meningitis, a very serious infection of the coverings around the brain and spinal cord.

The disease is more likely to spread to other areas of the body in people who have weak immune systems. This includes pregnant women, people who have HIV, people who take medicines that weaken the immune system, and people who have diabetes.

Talk with your doctor if your symptoms are severe or last more than a few weeks, or if you have a weak immune system and have valley fever.

How is valley fever diagnosed?

Your doctor will ask about your symptoms and do a physical examination. He or she may ask if you have travelled in areas where valley fever occurs. You may have a chest X-ray and a blood test to look for the fungus. In some cases, the doctor may take samples of body tissues for a biopsy.

How is it treated?

Most people with valley fever get better without treatment. For severe cases, doctors may prescribe antifungal medicines. People who are more likely to have the disease spread to other areas of the body often get antifungal medicines even if they have no symptoms.

To make sure you are getting better, it's important to have follow-up visits with your doctor. You may have a chest X-ray or another blood test after several months to make sure.

There is no medicine to prevent valley fever. But you may be able to stay away from areas where valley fever is common.