Stanislaus County has seen an upsurge of valley fever this year, and the threat is worse for residents on the west side of the county, health officials said.
As of late November, almost 120 people in the county had been stricken with the fungal lung infection that may cause devastating illness, and more cases are expected before year’s end. This year’s count is more than triple the annual number three years ago before a resurgence of the disease.
Valley fever is caused by fungal spores in certain types of soil in the San Joaquin Valley. Beside the 118 cases this year, the county had 88 cases last year, up from 54 in 2015 and 35 cases in 2014.
The county Health Services Agency pointed to clear evidence the disease is more prevalent in certain areas based on the distribution of cases across the valley. People in the western portion of Stanislaus County are almost five times more likely to be diagnosed with valley fever than residents on the east side, the agency said.
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No reason was given for the increased danger on the west side. People may come down with valley fever symptoms after breathing in spores in the dust stirred up by construction, tilling or the wind.
The disease, also known as “cocci”, is caused by the coccidioides fungus. Symptoms usually occur from 10 to 15 days after exposure to the fungus.
Dr. Julie Vaishampayan, county public health officer, said doctors and patients on the west side should understand the risk is higher for them, though the illness can strike anywhere in the county. Other groups that are vulnerable include seniors, pregnant women, diabetics and people with health conditions that weaken their immune system.
“If they are in a group of people at higher risk, they should consider taking precautions against inhaling a lot of dust,” Vaishampayan said.
A majority of people infected will not have symptoms. A valley fever illness similar to the flu will make people sick for two weeks or more before they recover.
With the most serious cases of valley fever, people have complications such as pneumonia and infection of the brain, joints, skin and other organs. Fewer than 200 deaths are associated with disease in the United States in a normal year, according to a study cited by the Centers of Disease Control and Prevention.
Milton David, a retired physician in Modesto, said he believes that dust from the fall almond harvest raises the valley fever risk for everyone in the county. As an orthopedic surgeon for many years, he would occasionally see infected local patients with cocci lesions on their tendons, muscles and joints.
“When they throw that dust into the air, naturally people are going to breathe those spores and get valley fever,” David said. “It is a real significant illness.”
He suggested that a change in harvesting practices could reduce the dust, such as using a funnel-like device wrapped around a tree to catch the nuts and suck them into a bin. Airborne almond dust is usually caused by employees sweeping the nuts into the rows between trees.
In 2016, almonds valued at $930 million were the county’s leading farm commodity, with the harvest including 182,000 acres of trees.
Vaishampayan said she had no knowledge of a link between almond dust and valley fever. “It would be a difficult theory to prove,” she said. Health information on valley fever usually refers to cocci spores in dirt that has not been disturbed in some time, she noted.
Carissa Sauer, a spokeswoman for the Almond Board of California, said the industry group is working on the problem of almond harvest dust.
"We've been working with almond farmers to improve practices with current harvesting equipment, as well as manufacturers to build even better low-dust equipment," Sauer said. "Beyond that we're researching other options for harvest that would change the process entirely. This is long-term research, but we understand the importance to our neighbors."
The Modesto-based Almond Board had no comment on any link between almond dust and valley fever.
One theory for the two-year spike in valley fever —more than 200 cases since the start of 2016 —was stormy winters that promoted the spread of the fungus in moist soil conditions.
Stanislaus County has far fewer cases of valley fever compared with areas in the southern San Joaquin Valley. Kern County had 40 percent of the 5,400 reported cases in California in 2016. The statewide count in 2016 was the highest on record and similar to a surge of 5,200 valley fever cases in 2011.
To stay healthy in valley fever territory, people should avoid breathing in dirt or dust. It’s also advisable to stay inside and keep the windows closed on windy days or when there’s dust in the air.
People who are outdoors in dusty conditions can avoid cocci infection by wearing an N95 respirator mask, which are available in hardware stores.