Winter storms trigger potential spike in Valley fever

Dry weather means dormant spores of Valley fever may soon take flight, multiple public health departments advise caution against the disease after this year’s winter storms

close-up detail of an unrecognizable farmer digging the earth with a sickle and kicking up dust. moving picture
close-up detail of an unrecognizable farmer digging the earth with a sickle and kicking up dust. moving picture
Darren Fraser
Published August 4, 2023  • 
1:00 pm

CENTRAL VALLEY – California’s record rainfall last winter curbed the drought, replenished lakes and reservoirs and dropped a wet blanket over fungal spores laying dormant across the Central Valley. However, with soaring temperatures baking the earth and with no rain in sight, health officials warn conditions are ripe for an increase in Valley fever infections.

Dr. Sharon Minnick, the senior epidemiologist for the Tulare County Health and Human Services Agency, said it is not uncommon for the Central Valley to see a rise in Valley fever infections following a wet winter.

“It’s a pattern,” Minnick said. “When there is a wet year, it gives rise to the fungus that spreads the disease.”

There are risks, albeit minor, to homeowners working in their yards. But Minnick said the greatest risks for spreading the airborne spores come from construction sites.

“Particularly where they are disturbing new ground,” said Minnick.

Minnick said residents need to take basic precautions. These include wetting earth before disturbing it. With respect to individuals working at construction or building sites, she advised wearing face masks, although that may be inconvenient. 

“August is Valley Fever Awareness Month,” Minnick said. “We will be publishing educational materials on our website and social media.” Minnick recommended that people visit to check the quality of air.

The California Department of Public Health (CDPH) noted that while people can catch the disease at any time of the year, most cases are diagnosed or reported in the fall. Not only that, but because it takes weeks for infected individuals to display symptoms, this means most people contract the disease in June through September, during drier times of the year.

According to CDPH, Fresno County recorded 407 cases of Valley fever in 2021; Tulare County had 317 cases. State totals have fluctuated since 2018, in which there were 7,636 cases. In 2019, there were 9,090 cases statewide, followed by 7,252 cases in 2020 and 8,030 in 2021.

The disease is most prevalent in the Southwest. According to the CDC’s (Centers for Disease Control and Prevention) Fungal Diseases data, in 2019 Arizona recorded 10,359 cases. Nevada, New Mexico and Utah combined for 350 cases while the rest of the country accounted for 290 cases. With the exception of cases occurring outside of the Southwest, the number of reported cases increased over those reported in 2018.

The Fresno County Department of Public Health (FCDPH) published a pamphlet for the public on all things related to the disease. According to the pamphlet, individuals at risk include anyone spending time outdoors in western Fresno County. Outdoor workers and construction workers are also at higher risk for contracting the disease.

Other at-risk groups include individuals with weakened immune systems, pregnant women in their third trimester, African-Americans and individuals of Filipino descent.

To avoid contracting the disease, FCDPH recommends that people remain indoors with the windows closed when the weather turns windy. The department also advises that people wear masks when engaged in any activities that may involve dust, such as gardening or digging and, if possible, always wet dirt before digging. 

Symptoms of Valley fever may include fever, cough, headache, rash, and muscle and joint pain. Individuals who come down with advanced cases of the disease may develop skin lesions. These individuals are also at risk for developing chronic pneumonia, meningitis and bone or joint infections.

According to FCDPH, approximately 40% of people who become infected will develop symptoms that may require medical treatment. Symptoms will not go away on their own.

Darren Fraser