FEATURE | Posted Jan. 27, 2016

Valley fever re-emerges in California

What you need to know

Photograph of California valley fever map © CDPH
More than 75 percent of valley fever cases have been in people who live in the San Joaquin (Central) Valley. Source: California Dept. of Public Health

Valley fever has been on the rise in California. While the fungal infection is at best an annoyance for the majority of people who contact it, for a few it can lead to serious or life-threatening complications. That drives physician-scientists like UC Davis infectious disease professor George Thompson to search for more knowledge about the disease and new ways to treat it.

Some things you should know about valley fever from UC Davis and federal and state health authorities:

1. Valley fever is a respiratory infection caused by a fungus that lives in arid soil.

Valley fever is a respiratory disease caused by the fungus Coccidioides, which lives as microscopic spores in soil in the southwestern parts of the United States and parts of Mexico, Central America and South America. When the ground is disturbed by wind, construction, farming or other movement, the spores become airborne and can be inhaled, infecting the lungs and other parts of the body via the bloodstream.

2. Valley fever is not contagious, but its incidence is high in Calif.

The majority of cases of valley fever occur among those who live, work or visit endemic areas. About 150,000 people in the U.S. get valley fever each year. According to the California Department of Public Health, the number of reported cases has quintupled from about 816 cases in 2000 to more than 4,000 cases in 2012. The increase may be due to changes in temperature, rainfall and other factors which can affect fungal growth.

3. Symptoms of valley fever are usually similar to the flu.

Sixty percent of those exposed to the fungus do not develop symptoms or have mild flu-like symptoms that resolve on their own. But a very small proportion of people (1 to 3 percent) develop disseminated disease that causes chronic pneumonia, joint pain, fever, fatigue or meningitis, a potentially fatal infection of the membranes and fluid covering the brain and spinal cord. Sometimes there’s a delay in diagnosis because the symptoms resemble common illnesses such as flu and bacterial pneumonia.

4. Anyone can get valley fever, but those over the age of 60 have a higher risk.

Anyone can get valley fever if they live in or have visited an area where the fungus Coccidioides lives, especially southern Arizona or California’s Central Valley. The infection is most common among older adults, particularly those ages 60 and older. People who have recently moved to an area where the disease naturally occurs are also at higher risk for infection.

According to the Centers for Disease Control and Prevention, some other high-risk groups include:

  • African-Americans
  • Asians
  • Women in their 3rd trimester of pregnancy
  • People with weak immune systems, including those with an organ transplant or who have HIV/AIDS

5. It can be difficult to avoid the fungus that causes valley fever.

In areas where valley fever is common, it’s difficult to completely avoid exposure to the fungus that causes valley fever. People with weak immune systems or who are at high risk for developing the severe form of the disease for another reason should consider trying to reduce their exposure to the fungus by limiting activities that disturb soil or generate dust, such as digging or excavation, in areas where the fungus lives.

6. Awareness is important.

man with his dog and cat © iStockphoto
Like people, dogs and cats are susceptible to valley fever.

There is no vaccine to prevent valley fever — and as noted previously, sometimes there’s a delay in diagnosis because the symptoms resemble common illnesses such as flu and bacterial pneumonia. Despite the frequency of valley fever for those living in endemic regions, few clinicians think of this disease early in the course of a patient’s illness.

If you have symptoms of valley fever and you live in or have visited an area where the fungus that causes the infection is common in the environment, ask your doctor to test you for valley fever. If you have valley fever, you may need treatment with prescription antifungal medication.

About one to three percent of those with valley fever develop the chronic version and must remain on antifungal medications to prevent recurrent bouts of infection.

7. Not just humans.

Valley fever has been found in everything from sea otters and llamas to primates and cattle! Like people, dogs and cats are susceptible to valley fever. Symptoms often include lethargy, weight loss, fever and coughing. Domestic animals are often treated with the same drugs that humans are prescribed.