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Valley Fever cases spike in Central Coast counties

USDA/Lance Cheung
A farmer tilling a field in the Salinas Valley.

The number of new Valley Fever cases in California is on path to make 2017 a record-breaking year. 

While the scientific name is coccidioidomycosis, it's called Valley Fever because it was first identified in California's San Joaquin Valley. The illness is caused by a fungus spore, Coccidioides immitis (C. immitis), that grows in soil. When it becomes airborne because of wind or farming activities, people can get infected by breathing in the spores.

Numbers released by California’s Department of Public Health (CDPH) show a jump in reported cases of more than 33 percent so far this year over the same period last year. While these are not yet confirmed cases, Dr. James Watt with Public Health said the state is on track to beat 2016's record numbers.

"I think that's likely. We won't know for sure for a few of months, but we did want to make sure that people were aware that disease levels were up and that they could take steps to protect themselves from Valley Fever," Watt said.

Those steps include remaining indoors on windy days and using recirculating air conditioning in vehicles. The state says it's unknown why cases appear to be on the rise, but last year's heavy rains could have reactivated the spores in some areas.

The CDPH reports that on the Central Coast, cases of Valley Fever have increased dramatically from 2015 to 2017. In San Luis Obispo in 2015, there were 35 suspected, probable and confirmed cases of Valley Fever. This year that number jumped to 181. In Santa Barbara County, over the last two years, the number of cases has gone from 13 to 51. And in Monterey County, Valley Fever cases have spiked from 20 in 2015 to 66 this year.

The public health department data shows onsets of the disease start spiking in mid-summer.

“Temperature, moisture, salinity and pH of the soil have all been considered separately in the geographic distribution of the fungus,” according to a study in the periodical Aerobiologia. “However, the specific environmental conditions that may produce an outbreak of coccidioidomycosis are not well understood in space and time.”

Another researcher pointed out that most Valley Fever victims are agricultural or construction workers, whose work is chiefly outside, and the disease often affects low-income communities.

KCBX's Greta Mart contributed to this report.

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