Valley fever cases are up almost 50% in Arizona in 2024. Here's what to know

With fall and winter approaching, seasonal illnesses like the flu are already spiking. There is another to add to the long list of illnesses to look out for — Valley fever.

The number of Valley fever cases in Arizona jumped by 45% in 2024 compared with the same time last year, an uptick of almost 4,000 cases.

Valley fever, also known by its clinical name coccidioidomycosis, is a lung infection that is rarely fatal and typically goes away without treatment.

During the first 10 months of this year, the Arizona Department of Health Services reported a total of 11,801 confirmed and probable cases of Valley fever, higher than last year's total count of 10,990.

Hot and dry conditions are favorable for the growth of the fungus that causes the infection, coccidioides. The fungus is endemic to the Valley metro area, and Maricopa County alone accounts for about half of all infections across the U.S., according to Dr. John Galgiani, the director of the University of Arizona Valley Fever Center for Excellence. The fungus also grows across the Southwest and is prevalent in regions of southern California, though cases have been reported as far north as Washington.

The fungus releases its spores when the dirt and dust are disturbed, and infection can occur when a person inhales these spores.

There's no vaccine to protect against Valley fever, though one is in development at the UA.

The good news is that Valley fever is not contagious; a person has to be exposed to the fungal spores in order to contract the infection.

"People who have Valley fever don't have to be isolated," since the disease isn't communicable, said Galgiani. "They're not risky to their grandkids or things like that."

Diagnosis of Valley fever is difficult because symptoms are similar to other illnesses that tend to spike in the fall and winter. Galgiani and his team at UA have partnered with Banner Health to work on the identification and reporting of the disease.

"We're slowly getting that done now in urgent care, but it was with a systematic approach to repeatedly remind people" to test for Valley fever, he said.

Here's what Arizonans need to know about Valley fever.

Fluctuating environmental patterns cause year-to-year differences Better knowledge and identification of symptoms may contribute to the increase, and manufacturing issues leading to false positives also play a role in the uptick. What factors into the increase the most is actually the environment, Galgiani said.

"Most likely, (the increase) is mostly because of year-to-year differences in rainfall, its timing and amounts and other weather patterns," he said.

The fungus that causes Valley fever likes climates that are hot and dry — describing central and southern Arizona perfectly. Phoenix sits right on top of the endemic region of the fungus, and Maricopa County accounts for half of total U.S. cases, according to Galgiani.

With Phoenix experiencing the hottest summer on record, the heat and lack of measurable precipitation created the perfect storm for the fungus to thrive.

"The modeling for climate change is that it will, over this century, get to the Canadian border," Galgiani said. "We'll see if that holds true, but the model would be that the endemic region will expand across the western United States."

Coccidioides spores can be disrupted through wind, dust storms and other activities that stir up dust and dirt. Even hiking and horseback riding can disturb the ground enough to release the microscopic spores.

Symptoms are similar to other fall illnesses As with other illnesses that spike in the fall and winter, fever and cough are just some signs pointing toward Valley fever. Other symptoms include fatigue, shortness of breath, muscle aches or joint pain and headache, all of which are similar to other illnesses and spell trouble for diagnosis, Galgiani said.

Symptoms show up about one to three weeks after inhaling the spores. Chronic infection can lead to pneumonia, though those symptoms are most common in those with weakened immune systems. Knowing the cause of pneumonia-like symptoms can make or break treatment for Valley fever. Pneumonia-like symptoms can be treated with antibacterial or antiviral drugs, but those types are ineffective against Valley fever because it is a fungal infection.

The most severe infection, disseminated coccidioidomycosis, happens when the fungus spreads beyond the lungs and into other parts of the body, including the skin, bones and brain. Disseminated coccidiomycosis occurs in 1 to 2% of cases.

On average, there's a 3 to 4% chance of contracting Valley fever, and the risk is cumulative depending upon a long a person lives in an endemic region.

"Twelve years...is the median length of residence before you get infected, before you get diagnosed," Galgiani said.

Increasing awareness can help diagnose sooner Diagnosis of Valley fever requires a blood test, one that is not included in routine lab work when a person goes to the emergency room or urgent care, Galgiani said.

"Being tested is not a bad idea if you're sick," he said, especially if a person has long-lasting or severe flu or pneumonia symptoms.

Immediate testing and diagnosis can prevent wasted time trying different drugs that are ineffective.

"You're getting all these antibiotics that are doing no good, and you might get repeated CAT scans and all sorts of healthcare utilization that you can stop doing once you have a diagnosis secure," Galgiani said.

Through a partnership with Banner Health, Galgiani is hoping to change the way Arizona health care systems treat Valley fever in emergency rooms and urgent cares.

"It's just a matter of paying attention to it and getting people to do what they're supposed to do," he said. "If this continues to be what we do at Banner, hopefully it will rub off on the rest of the health care systems."

A vaccine is on the horizon Galgiani's team at the UA recently developed the first vaccine to prevent Valley fever, a vaccine of the canine variety.

Around 6 to 10% of dogs in Maricopa, Pima and Pinal counties contract Valley fever yearly, according to the Valley Fever Center for Excellence . The spores are breathed in, just like in humans, and they do not spread from dogs to humans.

Researchers are hopeful the federal government will approve their shot by next year, allowing veterinarians to begin administering it to dogs and other animals they think may benefit from it. Cats and even zoo animals can catch Valley fever.

The UA research team received a grant from the National Institutes of Health to take the dog vaccine and engineer a human version of the vaccine, one that Galgiani says is necessary as the endemic region spreads.

"If there becomes more fungus in the soil and more spores get in the air...there can be five times as many cases every year," he said. "It'll make the idea of having a vaccine that much more appealing."

One unique feature of Valley fever is that it is does not spread from person to person, meaning that a vaccine would not be required for something like herd immunity.

"Some people don't like vaccines, and in this case, nobody has to get vaccinated if they don't want to because (infections are) not communicable," Galgiani said.

Without a vaccine, though, management of symptoms is all an infected person can do. Because it is a fungal infection and not a viral or bacterial infection, antibiotics and antibacterial drugs are ineffective against the infection.

For those with a severe infection, treatment can include an oral antifungal medication for three to six months, according to the CDC . Valley fever is also only fatal if the infection spreads outside the lungs, which is rare.

Most people get better on their own, Galgiani said. Still, he urged to see a doctor if you are feeling sick.

"The earlier you diagnose it, the more you can manage your illness," he said.