Understanding Valley Fever

Valley Fever, medically known as coccidioidomycosis, is a lung infection caused by inhaling spores of the fungus Coccidioides immitis or Coccidioides posadasii found in soil across California and the southwestern U.S.

This dimorphic fungus—meaning it exists as mold in soil and transforms into yeast-like forms in the human body—spreads when spores become airborne through wind, construction, farming, or other soil-disturbing activities.

A Growing Public Health Concern

In recent years, California has seen a sharp rise in Valley Fever cases:

In 2024, there were nearly 12,500 reported cases—the highest on record.
By mid-2025, 6,761 cases had already been logged, nearly double the 10-year average for that period.
The surge is especially worrisome in new hotspots like Monterey, Contra Costa, and Fresno counties, with Monterey jumping from 47 cases in 2023 to 348 by July 2025.
Experts attribute this increase to climate patterns—drought followed by heavy rain, combined with hotter, drier climate trends, are fueling the fungus’s spread.

Symptoms of Valley Fever: From Mild to Severe

Valley Fever often mimics flu or pneumonia. Many people (up to 60%) are asymptomatic, while others experience:

Fever, cough, fatigue, shortness of breath
Headache, joint and muscle pain
Skin rash, particularly on legs (erythema nodosum)

Though most recover, about 3–5% progress to chronic lung disease or disseminated infection—where the fungus spreads to bones, skin, or even the brain, causing severe complications.

Diagnosising and Treating Valley Fever

If symptoms persist for more than a week and you’re in a risk area, see a doctor right away. Diagnosis often uses:

Blood tests such as ELISA or complement fixation
Imaging like chest X-rays or CT scans to detect lung involvement

Most mild cases resolve on their own. Severe or disseminated cases may require antifungal treatment for several months, with drugs like fluconazole or amphotericin B.

Who’s at Higher Risk?

Certain individuals are more likely to suffer severe outcomes:

Older adults (especially 60+)
Immunocompromised individuals, pregnant women (especially late pregnancy), and those with underlying health conditions
People of Filipino, Black, or Hispanic background face significantly higher risk of severe dissemination

Preventing Valley Fever Infections

Valley Fever isn’t contagious—it spreads only via airborne spores. To lower your risk:

Avoid dusty areas when outdoors in endemic zones
Keep car windows closed and set ventilation to recirculate
Wet soil before digging or soil handling
Wear a properly fitted N95 mask during dust exposure

Why It Matters: Beyond the Numbers

Valley Fever is underdiagnosed; actual U.S. cases may range between 206,000 to 360,000 annually, compared to the ~20,000 reported.
Pets are also at risk, especially dogs, who can mirror human disease symptoms.
While a vaccine doesn’t yet exist for humans, one for dogs shows promise and may pave the way for human applications.
With climate change accelerating, Valley Fever is emerging as a long-term public health challenge, not just for California but potentially nationwide