Valley Fever Cases Climb Again in California: What You Should Know

A Silent Lung Infection Is Gaining Ground in 2025

Valley Fever (Coccidioidomycosis) has over 20,000 cases reported annually in the U.S., according to the CDC. However, experts believe this number is underreported. California and Arizona account for nearly 95% of all U.S. cases.Representative Image: FreePik

Published on:

21 May 2025, 6:00 pm

Valley fever, a serious lung infection caused by breathing in a soil-dwelling fungus, is on the rise again across California. So far in early 2025, more than 3,100 cases have been confirmed, surpassing last year’s tally and raising red flags for public health experts.

Counties like Kern, Los Angeles, Monterey, and Fresno have been hardest hit, but cases are now spreading to new areas. With the state’s wet winter followed by an increasingly dry summer, experts warn that the risk of infection could increase.

What is Valley Fever?

Valley fever, officially known as coccidioidomycosis, is a lung infection caused by Coccidioides, a fungus commonly found in dry, dusty soil in the southwestern United States, especially in California and Arizona. When soil is disturbed by wind, construction, farming, or wildfires, the spores become airborne. People can become infected simply by breathing them in. While most cases are mild or even asymptomatic, the infection can cause serious respiratory problems and, in rare cases, spread to the brain or other parts of the body.

Common symptoms to watch for

Many people experience flu-like symptoms, including:

Fatigue
Fever and chills.
Cough
Headache
Shortness of breath
Night sweats.
Muscle and joint pain
Skin rash

In about 10% of cases, the infection can cause long-term lung problems such as pneumonia. About 1% can experience serious complications, as the fungus spreads beyond the lungs.

Sick businesswoman blowing nose while working in the office

A 2022 study projected that climate change could expand the fungus's range northward, potentially increasing infections by 50% by 2100.Representative Image: FreePik

Who is most at risk?

Valley fever is not contagious, but certain groups are at higher risk of severe illness:

Older adults
People with weakened immune systems
Pregnant women
Outdoor workers, especially those in construction, farming, and oil fields.

Kern County has long been a hotbed, but new hotspots are emerging. In Contra Costa County, cases have tripled since 2023. Merced and San Bernardino have also seen rapid increases.

Why California’s weather plays a role.

The state’s extreme weather patterns are driving the increase. Wet winters create ideal conditions for the fungus to grow. When followed by dry, dusty summers, those fungal spores are released into the air, increasing the risk of exposure.

Health officials say the pattern is becoming more predictable and more dangerous.

There is no question that the number of cases of coccidioidomycosis is enormously higher than before. If you want to see me, right now you’d have to wait until July, and that goes for my colleagues, too

Dr. Royce Johnson, Chief of the Division of Infectious Diseases and Director of the Valley Fever Institute, Kern Medical, California

What you can do to stay safe.

While you can’t completely eliminate the risk, especially in high-exposure areas, you can:

Avoid dusty outdoor environments when possible.
Wear an N95 mask in dusty conditions.
Keep windows closed during dust storms.
Shower and change clothes after outdoor activities.

If you live or work in an affected area and develop flu-like symptoms that don’t get better, consider asking your doctor about Valley Fever. Early diagnosis and treatment can prevent serious complications.

(Input from various sources)

(Rehash/Muhammad Faisal Arshad/MSM)

Bridging Expertise and Global Ambitions: Dr. Greeshma B on Her Dental Career

disease outbreak

California

Valley Fever Cases Climb Again in California: What You Should Know

Related Stories