Changing climate raises valley fever risk

pgeweather@pge.comMay 11, 2013 

The recent outbreak of valley fever that sickened 28 workers at the two solar power construction sites in eastern San Luis Obispo County has increased awareness of the disease.

Health officials say valley fever is infecting a greater number of people around the state and nation as the climate warms and droughts intensify. A drier climate produces more dust that spreads the fungus-laced spores that cause the fever by wind as well as human activity.

The weather plays a significant part in outbreaks of valley fever or coccidioidomycosis.
(Physicians often call it cocci for short.) The spores grow during wet periods then are disbursed in dry conditions. In other words, our Mediterranean climate with its dry and wet seasons contributes to this “grow and blow” cycle.

This was certainly the case from 1975 through 1977 with the terrible drought that struck California. The San Joaquin Valley was declared a disaster area. Its soils were even more parched than normal.

On Dec. 20, an exceptionally strong area of high pressure moved southward over the Great Basin. At the same time, an intense low-pressure system and its associated cold front approached the coast of Northern California and produced an extraordinarily steep pressure gradient. Some of the strongest winds ever recorded in California history blew across the southern San Joaquin Valley that day and, combined with the extraordinarily dry soil, produced a fearsome dust and sand storm. The U.S. Geological Survey estimated that wind gusts reached 192 mph at Arvin!

Not surprisingly, large volumes of dust were carried northward through the San Joaquin and Sacramento valleys toward the Oregon border. Dust from this storm obscured the sun as far north as Colusa County.  Months later, PG&E hydrographers found a layer of dust embedded in the snowpack in Mount Shasta.
An outbreak of valley fever followed as spores traveled into Sacramento and Redding. A great ape at the San Francisco Zoo succumbed to the fever.

San Luis Obispo County’s health officer Dr. Penny Borenstein told me, “Cocci is difficult to avoid and there is no vaccine.  Workers involved in any soil-disrupting or digging activity are most at risk for valley fever, but anyone can become infected.   It may help to wet down dry soil before digging, especially ground that has been undisturbed, and avoid being outdoors when dust is visible in the air.”

She also recommended that removing “clothes and shoes before leaving a dusty worksite will avoid carrying the fungus into the home. If you think you may have become ill with valley fever, it is important to seek medical care early.”

It usually takes one to four weeks for symptoms to start. About two-thirds of the people who are infected never notice any symptoms. Many people are able to fight off valley fever on their own without treatment. However, a third of those who get it can develope fatigue, fever, cough, rash, chest pain, headache and joint aches.  Tragically, nearly 1 percent of the people who get valley fever die from it. Also, newcomers may be more susceptible.

•  •  •

Did you know? PG&E delivers some of the nation’s cleanest power.  Nearly 60 percent of the electricity the company provides to customers comes from sources that are renewable and/or emit no greenhouse gases.

John Lindsey’s column is special to The Tribune. He is vice president of the Point San Luis Lighthouse Keepers. He is a media relations representative for PG&E and a longtime local meteorologist. If you have a question, send him an email at

The Tribune is pleased to provide this opportunity to share information, experiences and observations about what's in the news. Some of the comments may be reprinted elsewhere in the site or in the newspaper. We encourage lively, open debate on the issues of the day, and ask that you refrain from profanity, hate speech, personal comments and remarks that are off point. Thank you for taking the time to offer your thoughts.

Commenting FAQs | Terms of Service