What you need to know about Valley fever after 19 infected at California music festival

Several people were recently infected with a fungal lung infection at an outdoor California music festival.

As of Aug. 21, at least 19 people who attended or worked at the "Lightning in a Bottle" festival in Kern County in late May tested positive for Valley fever, according to the California Department of Public Health. At least eight people have been hospitalized.

What's more, a recent study found cases of Valley fever have increased dramatically in California over the last two decades and droughts may be playing a role in seasonal peaks.

Here's what you need to know about the infection including signs and symptoms, how it is treated and how to best protect yourself.

What is Valley fever?

Coccidioidomycosis, more commonly known as Valley fever, is a lung infection caused by breathing in spores from a fungus called Coccidioides, according to the Centers for Disease Control and Prevention (CDC).

"It's a fungus that lives in soil in certain areas around the world," Dr. Daniel Pastula, chief of neuro-infectious diseases and global neurology at the University of Colorado School of Medicine and Colorado School of Public Health, told ABC News. "So, classically, the southwestern United States, so California and Arizona are kind of prime states where this occurs."

He said the fungus can also be found in parts of Washington state, in Mexico and in parts of South and Central America during "hot, arid summers and mild winters."

The disease is called Valley fever because it was first discovered in the San Joaquin Valley, which is in the southern half of California's Central Valley.

There is currently no evidence of person-to-person transmission. The CDC says pets can also get Valley fever, but there is no evidence of transmission between animals and people.

Those most at risk of severe disease include those with weakened immune systems, people with diabetes, older people and women who are pregnant, according to the CDC.

What are the signs and symptoms?

Many people exposed to the fungus never develop symptoms. Those who do develop symptoms see signs about one to three weeks after exposure, according to the CDC.

Symptoms include cough, fever, headache, fatigue, shortness of breath, night sweats, muscle aches, joint pain and a rash.

Patients usually experience symptoms from a few weeks to a few months. If an infection becomes severe, symptoms may last longer.

Between 5% and 10% of Valley fever patients may develop serious or long-term lung problems and about 1% see the infection spread outside their lungs to other parts of the body, the CDC said.

"A very small portion will develop what we consider pneumonia," Dr. Rachael Lee, an associate professor in the division of infectious diseases at the University of Alabama at Birmingham, told ABC News. "So, you can see it on a chest X-ray. They may be coughing. They could lose weight."

Should I get tested?

Because Valley fever symptoms can resemble other infections, patients may consider getting tested if their symptoms do not improve, according to CDPH.

People may get a blood test to confirm a Valley fever diagnosis, or a health care provider may perform a skin test to see if they've had Valley fever in the past or are currently infected, the CDC said.

Lee said not all patients need to be tested and it may depend on their travel history.

"But if they went to California or Arizona, and they have concern for being exposed to this" then doctors may consider testing, she noted.

How is it treated?

Many people with no symptoms or mild symptoms will have the infections go away on their own without any medicine.

However, for those who get more severely sick or are at risk for severe illness, they may be prescribed an oral anti-fungal medication, such as fluconazole, for three to six months.

In rare cases, Valley fever can develop into meningitis, which is fatal if untreated, and could lead to lifelong anti-fungal treatment, according to the CDC.

"When people have disseminated infections that's spreading to the joints, the bones, as well as the brain, more intense courses of anti-fungal treatment, and potentially other treatments, are needed for those people," Pastula said.

How do I prevent Valley fever?

There are currently no vaccines that protect against Valley fever, although scientists are continuing to work on a vaccine, the CDC said.

It can be difficult to avoid breathing in the fungus in areas where it is prevalent, but there are steps people can take to reduce their exposure, according to the experts.

"If you are not immunocompromised, do your best to not get exposed to large amounts of dust, in general, especially if you're in those areas of California and Arizona," Lee said. "If you are immunocompromised, I would really think about where you're going and what you're doing. Potentially, you could wear something like a mask."

The CDC also recommends using air filtration measures indoors and cleaning injuries well with soap and water to reduce the risk of infection.

Pastula said it's important for people to educate themselves on the fungi because climate change may cause Valley fever to appear in other areas of the U.S.

"Climate change might be playing a role in where [the fungus] might be living because this fungus has evolved to a specific ecologic niche, and if that niche expands because of climate change, we're going to see [it] potentially expand to ranges that hadn't been before," he said.