Valley Fever: Diagnosis and Treatment

Benjamin J. Park, MD


July 22, 2013

Editorial Collaboration

Medscape &

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Valley Fever

Valley fever can be a debilitating and costly respiratory disease that is increasingly common in some areas, such as the southwestern United States. Nearly three quarters of valley fever patients miss work or school because of their illness, for an average of 2 weeks, and more than one third of patients require hospitalization. In 2011, more than 20,000 cases of valley fever were reported in the United States, and many more cases likely went undiagnosed.[1]

Hello. I am Dr. Benjamin Park, a medical officer in the Mycotic Diseases Branch at the Centers for Disease Control and Prevention (CDC). I'm pleased to speak with you today about valley fever as part of the CDC Expert Video Commentary Series on Medscape.

Valley fever is caused by Coccidioides, a fungus that lives in soil in the southwestern United States and parts of Mexico, Central America, and South America. Inhaling the airborne fungal spores can cause a respiratory infection called coccidioidomycosis, also known as "valley fever." The infection cannot spread from person to person.

More than 65% of valley fever cases in the United States occur in Arizona, and 30% occur in California. Of note, in recent years, the incidence of reported valley fever has been increasing by approximately 15% per year,[2] which could be because of:

More people being exposed to Coccidioides because of increased travel or relocation to endemic areas;

Changes in the way cases are detected and reported; or

Changes in environmental factors, such as temperature and rainfall, which can affect the growth and distribution of Coccidioides.

Many people who inhale the fungal spores developing asymptomatic Coccidioides infection, which usually provides immunity against future infection. However, in approximately 40% of cases, patients develop flu-like symptoms, including fever, cough, headache, shortness of breath, rash, muscle aches, and joint pain. The symptoms typically appear between 1 and 3 weeks after exposure and can last for weeks to months. A small proportion of people develop chronic pneumonia, bone or joint infection, or meningitis.

Who Gets Valley Fever?

Anyone can get valley fever if they live in or have visited an area where Coccidioides is endemic, especially southern Arizona or California's Central Valley. It is most common among adults aged 60 years and older.

In addition, several groups of people are at higher risk for developing the severe or disseminated forms of the disease, including:

Immunosuppressed persons, such as those with HIV/AIDS or those who have had an organ transplant;

African Americans;

Filipinos; or

Pregnant women.

Valley fever is usually diagnosed using a serologic test, but because the symptoms are similar to those of other community-acquired respiratory illnesses, patients often experience delays in diagnosis and treatment.[3]