- Valley fever, an infection caused by soil-borne fungus, is on the rise in the southwestern US. In California, new cases rose 11% in 2018 compared to the same period in 2017.
- The condition is often misdiagnosed as the flu, since symptoms can include fatigue, cough, fever, night sweats, and headache.
- The disease is not contagious and often clears up on its own, but rare cases may cause serious long-term lung problems and require anti-fungal treatment. If the infection spreads, valley fever can be fatal.
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People who travel or work in the southwestern United States — specifically farm workers — have been reporting serious symptoms like coughing, high fever, and exhaustion that have landed some of them in emergency care, NBC News reported.
But it isn't the flu. Coccidioidomycosis, known as valley fever, is an infection caused by inhaling spores of Coccidioides fungus, which is found in soil and carried long distances by wind and weather. Unlike the flu, valley fever is not contagious from person to person — only direct exposure to the spores can cause infection, according to the Center for Disease Control and Prevention (CDC).
The condition is named for the San Joaquin Valley in central California, where it is endemic. However, it can also be found throughout Arizona, as well as in southern New Mexico and part of southwestern Texas.
Once relatively rare, valley fever is on the rise, in part because the fungus thrives in a climate of low rainfall, hot summers, and moderate winters, which are increasingly common in the southwestern United States. In 2017, the CDC reported 14,364 cases of valley fever. In California, confirmed cases of valley fever rose to 7,886 cases in 2018 — an 11% increase when compared to the same period in 2017, according to the California Department of Public Health.
"There are more Valley fever infections in California than anywhere else," said Dr. George Thompson, an infectious diseases specialist and director of the Center for Valley Fever at UC Davis Health in Sacramento, in a March press release. And cases may be under-reported due to similarity of symptoms with common ailments like the flu and pneumonia. Fever, night sweats, joint and muscle pain, shortness of breath, and a rash are common indicators of valley fever.
Most people who are exposed to the fungus don't get valley fever
Not everyone who inhales the Coccidioides spores will get sick, according to the CDC. About 40% of people exposed to the fungus will develop symptoms within one to three weeks of exposure.
A blood sample or skin test can confirm a valley fever diagnosis by the presence of antibodies to Coccidioidomycosis within a few days of going to the doctor.
The infection is most likely to affect people 60 years old and older, those with weakened immune systems, and pregnant women. Research also suggests people who are black or Filipino are more susceptible to severe symptoms if infected.
For most people, symptoms of valley fever will dissipate on their own over a period of several weeks or months.
But about 5% to 10% of valley fever patients experience long-term lung problems as a result of the infection, requiring anti-fungal drugs such as fluconazole. Treatment can take up to six months or more and require hospitalization, according to the CDC.
In very rare cases, the infection can spread from the lungs to other areas of the body such as the brain, spine, joints, or skin. This occurs in 1% of valley fever cases. It can be deadly if the infection develops into meningitis. On average, about 200 people die per year from valley fever and related complications, according to 1991-2016 data from CDC mortality statistics.
If you live in an area prone to Coccidioidomycosis, the CDC recommends taking precautions against infection by avoiding exposure to dust whenever possible. Stay indoors during windy weather, use an air filtration system in your home, and wash thoroughly with soap and water after contact with soil. Pets can also be infected, so take similar safety measures with the family cat or dog.
Editor's note: This story was updated on June 19.
