Valley fever on the rise in California


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Reported cases of valley fever--a flu-like illness caused by inhaling airborne spores of a dirt-dwelling fungus -- more than tripled in California from 2000 to 2006, and scientists don’t know why.

From 2000 to 2006, the number of California cases rose from 816, or 2.4 cases per 100,000 people, to 2,981, or 8 per 100,000, according to a study by the California Department of Public Health in today’s Morbidity and Mortality Weekly Report, a publication of the national Centers for Disease Control and Prevention.


Most illnesses occurred in the San Joaquin Valley, especially Kern County, which averaged 150 cases per 100,000 people. African Americans and Filipinos were most likely to develop rare but serious complications.

The study put forth a number of theories about why infections are rising. The increase could have to do with housing and other construction that disturbs soil and sends the spores flying. It could have to do with an increase in the number of people with chronic conditions that weaken their immune systems. (People with HIV are particularly susceptible to coccidioidomycosis, the official name for valley fever.) It could have to do with new people who have never been exposed to the fungi moving into places where it is plentiful.

About 60% of those infected never show symptoms. The rest develop a flu-like illness with cough, headache, muscle aches and fatigue that can last a month. About 1% develop a more severe illness that affects the brain, skin and other organs. People of African and Filipino descent may be more susceptible to this for hereditary reasons.

The illness is treatable with oral or injected anti-fungal medications, which is why the state and the CDC are alerting physicians to be alert to these symptoms in people who live or have traveled in areas where the fungi are found.

Two related types of fungi can cause the illness: Coccidioides immitis and Coccidioides posadasii. Besides the San Joaquin Valley, they can be found in parts of Arizona, Utah, Nevada, New Mexico, west Texas, Mexico and Central and South America.

California still trails Arizona, which reports the most cases of valley fever every year and has also seen an increase, from 1,812 cases (37 per 100,000) in 1999 to 5,535 cases (91 per 100,000) in 2006.

--Mary Engel