Valley Fever, Historically a Southwest Fungal Infection, May Be Spreading

Scientists predict that Valley fever, a historically southwest fungal infection, may begin to expand its borders due to changing weather patterns.

Sparked by the Coccidioides organism, Valley fever thrives in dry soil in southwestern states like Arizona, California, New Mexico, Nevada, Utah, and most recently, Washington. It sporadically gets kicked up into the air and can travel long distances, stay suspended in the air for hours, and get inhaled. From there, it can travel deep into the lungs and trigger an infection that causes a mix of respiratory symptoms.

“The reality is most people eventually get over it—but it is often an impacting disease of weeks to months, so it’s not like one or two days,” John Galgiani, MD, the director of the Valley Fever Center for Excellence in the University of Arizona College of Medicine Tucson, told Health. 

While Valley fever may not have reached your region of the country yet, understanding its symptoms, diagnosis, and treatment may be helpful for future prevention.

Here's What Valley Fever Looks Like

Valley fever shares certain similarities with respiratory infections, like fatigue, cough, fever, headache, and muscle aches. It can also cause a rash on the legs or upper body. In less than 1% of cases, the infection can spread to the spinal and brain, causing meningitis. According to Dr. Galgiani, many people who go to urgent care for Valley fever present with symptoms that look like pneumonia. 

There are certain groups that have a higher risk of contracting the infection and developing severe symptoms, including pregnant people, people with diabetes, Black and Filipino people, and individuals who are immune-compromised due to a condition like HIV/AIDS, an organ transplant, or immune-suppressing medications.

According to the Centers for Disease Control and Prevention (CDC), there were 20,003 cases of Valley fever reported in 2019 (mostly in Arizona and California)—though that figure probably underestimates the true case count. It causes about 200 deaths annually, though that number, too, is likely underestimated.

While Valley fever can be serious for some individuals, most people who inhale the fungal spores won’t get sick, and the majority of people who develop symptoms will recover without treatment in a matter of weeks, or in some cases, a few months.

How Valley Fever Spreads

Unlike most respiratory infections, Valley fever is not contagious. It does not spread through large respiratory droplets expelled during coughs and sneezes, but through contaminated soil. 

The tiny spores get into the air and travel long distances—you might assume hikers and campers face the greatest risk, but that’s not necessarily the case. “Most people get infected in downtown Phoenix, for example, just because that’s where most people are,” explains Dr. Galgiani. It spreads year-round but is most prevalent in the drier months (late spring to early summer).  

The overall risk of getting sick while visiting the Southwest is still pretty low. Dr. Galgiani, who has calculated the risk, says the chances of getting infected while visiting an area where it spreads (like Arizona) is 1 in 15,000. The chances of getting seriously ill are 1 in a million. “It’s a manageable risk,” notes Dr. Galgiani.

How Valley Fever Is Detected and Treated

Without a diagnostic test, it can be difficult for healthcare providers to discern whether someone has a respiratory infection like COVID-19 or Valley fever.

“You need a specific blood test to figure out that it’s not bacterial pneumonia or COVID or some other cause of pneumonia,” explains Dr. Galgiani. The diagnostic test looks for antibodies your body produced to fight Valley fever, and results are typically available within a few days. Imaging tests, such as chest x-rays or lung CT scans, and skin testing can help providers identify the infection, too.

Valley fever can look so similar to other respiratory infections that it’s regularly missed or misdiagnosed. “The symptoms of Valley fever are often similar to other respiratory infections in presentation and this leads to delays in diagnosis,” says George Thompson, MD, the co-director of the Center for Valley Fever at UC Davis Health.

Research has shown that delayed testing at urgent care clinics can lead to hospitalization, higher healthcare costs, being prescribed the wrong medications, and poorer health outcomes, so it’s worth asking your doctor for the blood test if you get sick while living in or visiting endemic regions.

There are five effective antifungal drugs for Valley fever, the most common one being fluconazole. These drugs aren’t officially approved for Valley fever, so doctors have to prescribe them for the infection off-label (this is common and entirely legal). Dr. Galgiani points out that the antifungals won’t cure the disease entirely, and some patients who develop more complicated infections may have to take the treatment for the rest of their life. But the vast majority of people recover and develop lifelong immunity, preventing them from getting reinfected.

Is Valley Fever Spreading?

As climate change warms up the earth, some scientists expect that Coccidioides will find new warm, dry environments to live and grow in. “The effect of climate change will increase the habitat that the fungus finds hospitable,” Dr. Galgiani said.

What does that mean for Valley fever? The infection may eventually become more common in the whole western United States, explains Dr. Galgiani.

It could travel north or east to states like Idaho, Wyoming, Montana, Nebraska, South Dakota, and North Dakota. “Valley fever is typically limited to the Southwest, but it is clearly moving north and east,” says Dr. Thompson. The majority of cases detected outside of the Southwest are in patients who recently traveled to the region. Most projections, however, currently predict that, even with warmer temperatures, it’ll stay west of the Mississippi, notes Dr. Galgiani.

Is There a Valley Fever Vaccine?

There is not a Valley fever vaccine, yet. Quite recently, however, scientists—including those at the University of Arizona—successfully developed a Valley fever vaccine for dogs that is currently in the process of being licensed, meaning it should be in veterinarian offices within the year, according to Dr. Galgiani. This is great news for our four-legged friends, but it also shows promise for our own vaccines. 

“Everything we did to bring the vaccine to animal health was also to provide evidence that this vaccine indeed likely would be good for humans,” Dr. Galgiani said. Scientists have shown that the vaccine works for dogs—the next challenge is to show that it works just as well in humans.

There are three vaccines in development for people, and according to Thompson, the National Institutes of Health have invested in making sure these vaccines will be ready in the near future. “We are hopeful that there will be a vaccine in the next decade,” concludes Dr. Thompson.