- Experts are sounding the alarm about the spread of a fungal infection called Valley fever.
- A recent outbreak at a California music festival sickened 19 and led to several hospitalizations.
- Valley fever is typically found in drier regions in the southwestern U.S., but drought and climate change are spreading the fungus to other regions.
- Most Valley fever cases resolve on their own, but some require medical treatment. In some cases, Valley fever can be deadly.
- There is no cure for Valley fever, but a vaccine is being developed.
Valley fever is a fast-emerging, dangerous fungal disease that spreads through dust in the air. Cases of Valley fever have risen dramatically over the past two decades.
The California Department of Public Health (CDPH) has warned of an increasing risk of Valley fever impacting the Central Valley and Central Coast regions this fall.
The CDPH warning follows a Valley fever outbreak at a music festival in Kern County in May with more than 20,000 attendees. According to CDPH, the outbreak sickened 19 and left eight festivalgoers hospitalized. The Lightning in a Bottle music festival took place at an outdoor recreational area surrounded by open spaces and farmland.
According to CDPH, more than 6,000 cases of Valley fever have been reported in California this year. Kern County has had the highest number of cases since CDPH began tracking the disease in 2001.
Valley fever is caused by the
The resulting lung infection is often asymptomatic but can sometimes lead to influenza-like illness with symptoms such as:
- fever
- cough
- difficulty breathing
- chest pain
Severe Valley fever cases may lead to brain infection, causing meningitis or death.
Most Valley fever outbreaks occur in California’s drier, central regions, but more cases are occurring in other regions, such as the northern Central Valley and Southern California.
Valley fever is named after the San Joaquin Valley in California. While the disease is typically found in the Southwest, scientists say it has spread to other regions as global temperatures increase.
Climate change is expected to worsen Valley fever outbreaks in the coming years.
A
Most Valley fever outbreaks occur from September to November, but rising global temperatures are making the outbreaks less predictable.
As such, a new study published in
The researchers found differences in both timing and seasonal patterns of outbreaks, which varied by year and in California counties. They found that, on average, counties with the most pronounced peaks included the San Joaquin Valley and Central Coast. The peaks began earlier in San Joaquin Valley.
“Most seasonal infectious diseases show a peak in cases every year, so we were surprised to see that there were certain years during which few or no counties had a seasonal peak in Valley fever cases,” said first author Alexandra Heaney, PhD, assistant professor at the UC San Diego Herbert Wertheim School of Public Health and Human Longevity Science,” said in a statement.
“This made us wonder what was driving these differences in seasonality between years, and based on the timing we observed, we hypothesized that drought might be playing a role. This is valuable information to time public health messaging aimed at educating the public about the symptoms of Valley fever and how to protect themselves,” Heaney continued.
William Schaffner, MD, professor of preventive medicine and infectious diseases in the Department of Health Policy at Vanderbilt University Medical Center in Nashville, explained that when an environment containing the fungus becomes very dry, and the wind picks up speed, the aerosolized spores can become inhaled and cause illness.
“Climate change may create more of these outbreaks, and they may well spread to other geographic areas in which this spore can survive in the soil,” Schaffner told Healthline.
Valley fever, or desert rheumatism, is caused by the fungus coccidiodomycosis, which lives as mold spores in soil.
This fungus is endemic in dry regions, mainly in the Southwestern United States and Latin America, but its geographic distribution has widened in recent decades.
Unlike other respiratory illnesses, valley fever is not contagious.
This means the Valley fever outbreak at the California music festival was caused by the coccidioidomycosis fungus in the soil, not through person-to-person transmission. “You have to get it from the environment,” Schaffner said.
Events like music festivals “disturb the soil,” Schaffner explained, which creates “small aerosols and permits some of these spores to be aerosolized, get into people, and some people will, as a consequence, become ill.”
Schaffner explained the fungus’s spore form has allowed it to evolve and survive in an ever-changing environment. “You can think of spore as a hibernating form of this fungus,” he said.
“It’s a heat-resistant fungus that can survive in arid environments for years. When this arid environment is disturbed, either by wind or by digging into it, and it becomes aerosolized microscopically, this spore can be inhaled down in the lungs and becomes a more aggressive form of the fungus that produces illness in humans and animals,” Schaffner continued.
According to the
- cough
- shortness of breath
- muscle aches
- rash
These symptoms may vary depending on the stage of the disease progression and which organs are affected.
“It starts as a respiratory disease and can be indistinguishable in symptoms from viral or bacterial pneumonia,” Emma Harvey, a pharmaceutical physician and head of Global Affairs at F2G, told Healthline.
While most symptoms of Valley fever infection are mild, around 5% of people may develop a chronic lung infection, which requires antifungal treatment.
Severe cases of coccidioidomycosis can be serious, causing nodules and cavities in the lungs and damage to the central nervous system, resulting in meningitis and possibly death. If Valley fever affects the bones and joints, it may lead to
Despite the potential risks of Valley fever infection, symptoms tend to subside spontaneously in most people, Monica Gandhi, MD, MPH, professor of medicine at the University of California, San Francisco, told Healthline.
“In mild disease (which most often goes undetected). Doctors don’t use treatment but in severe infections, they use antifungal therapy like fluconazole for many months,” Gandhi explained.
Of course, some individuals may face higher risks of severe illness from Valley fever than others, such as pregnant people, people living with HIV, and immunosuppressed individuals. People of certain races and ethnicities (i.e., Filipinx or African Americans) may also have higher risks of complications from Valley fever, Gandhi added.
There are ways to protect yourself if you live in the southwestern U.S. or another dry region that could be impacted by Valley fever.
Preventive measures include wearing a mask outdoors in affected areas. It’s also a good idea to wet down soil before disturbing it, particularly when gardening, doing yard work, or construction.
“That will reduce the chance that when you disturb the soil it will become aerosolized,” Schaffner said.
“Wet soil stays at ground level, whereas if it’s dry, as the soil is turned over, some of that dry soil will microscopically aerosolize,” he explained.
Scientists have been trying to develop a vaccine for Valley fever since the 1960s, but initial attempts in humans have been unsuccessful.
In 2021, researchers at the University of Arizona College of Medicine in Tucson developed a vaccine that’s highly effective in dogs.
Dogs, like humans, are susceptible to Valley fever. Gandhi explained that this two-dose vaccine creates an immune response against the fungus and protects dogs from developing disease when exposed to it.
The vaccine is not yet approved for use, which means rigorous research and clinical trials are still needed.
“It obviously needs testing for safety and effectiveness in humans. We want it to be careful; we want it to be thorough,” Schaffner said.
A Valley fever outbreak in California is raising alarm among public health officials.
The fungal infection, typically found in the southwestern U.S., is predicted to spread to other regions as global temperatures rise.
Symptoms of Valley fever generally include fatigue, shortness of breath, cough, muscle aches, and rash. Severe cases may result in meningitis or death.
There is currently no cure or vaccine for Valley fever, but most cases resolve without hospitalization.