California officials warn of increased risk for valley fever

California health officials are warning of a potential increased risk of valley fever, a respiratory disease caused by fungus that grows in soil across many parts of the state.

This winter’s heavy rains may have caused an increase in the growth of the Coccidioides fungus, which causes valley fever, the California Department of Public Health announced in a press release. Valley fever occurs when dust containing the fungus is inhaled, leading to respiratory symptoms that can turn severe or even fatal. 

Periods of heavy rain can cause the Coccidioides fungus to become more active, according to research conducted by the University of California, Berkeley and CDPH. That means valley fever cases could spike in the coming months, as spores that grew during this year’s record rainfall dry out and become airborne in dust.

“We had a wet winter following years of drought. This pattern in climate has been associated with large increases of valley fever in the past,” a CDPH spokesperson told SFGATE via email. 

Most cases of valley fever occur in California’s Central Valley, but rates of the disease have been increasing in areas along the Central Coast and in Southern California, according to CDPH data. Kern County has the highest rates of valley fever in the state, with 2,819 cases reported in 2021.

Statewide reports of the disease have increased significantly over the last two decades, from less than 1,000 yearly cases in 2000 to over 9,000 in 2019. About 1,000 people are hospitalized with the disease each year, and of those cases, one in ten results in death, CDPH data shows.

While about six in ten people who are infected will fight off the infection naturally, those who become sick may experience coughs, fevers, difficulty breathing and chest pain. People with severe cases of valley fever may need hospitalization, followed by extensive follow-up medical care. 

“Breathing in even a small dose of the fungus can lead to infection. CDPH does recommend measures for reducing exposure to dirt and dust to help prevent valley fever, including keeping car windows closed and using recirculating air, if available, when driving through areas where valley fever is common,” CDPH said. 

Those particularly at risk of contracting valley fever include people who live in areas where the fungus is common, especially those who work outdoors and in professions where dirt and soil are regularly disturbed – meaning people who work in construction and agricultural field work are especially at risk. Research conducted by UC Davis found California’s Hispanic and Latino farmworkers to be at a higher risk for contracting the disease, and CDPH data notes that 47% of California’s valley fever cases are among Hispanic and Latino people. 

The CDPH recommends avoiding dusty areas in places where valley fever is common. If that can’t be avoided, the agency advises wearing N95 masks in dusty areas, keeping windows and doors closed during periods of windy weather and wetting down soil before digging to prevent stirring up dust in the air.