Valley fever is a fungal infection transmitted in dust that can affect the lungs as well as other organs. It’s officially known as coccidioidomycosis or “cocci” for short and is more common in people and animals in Arizona and California’s San Joaquin Valley, where the illness was first detected over a century ago. But according to the Los Angeles Times, infection rates in California have soared 800% since 2000, and the disease is spreading to other states such as Washington, Oregon and Utah.

Researchers blame climate change for the spread of valley fever, which can cause fever, cough, headache, and fatigue, saying the cycles of extreme rainfall followed by worsening drought and heat are creating more of the dangerous dust. Wildfires can then fuel the spread of the dust. Valley fever may be a threat to the entire western United States by the end of the century, says the Times.

The American Lung Association says research has linked the increase in valley fever cases with the rise of  dust storms due to climate change. The National Oceanic and Atmospheric Association published a study linking the two. According to the NOAA, dust storms have clearly increased because of the warmer temperatures and increasing drier climate in the Southwest. While recognizing that they needed more research to be certain, the researchers found that these dust storms were the strongest explanation so far for the rise in valley fever.

“It’s emerging because we have increasing numbers, and it’s emerging because it’s being found in new areas,” said Dr. Nancy Crum, an infectious disease specialist in San Diego who has done extensive research in valley fever as well as other infectious diseases. “It’s a fungus in the soil, and so if you have really windy, dusty conditions, it can get from one area to the other.”

According to the Times, researchers estimate there are about 350,000 valley fever cases in the U.S. annually. The Centers for Disease Control and Prevention says about 60% of those affected never have symptoms but others may develop flu-like symptoms one to three weeks after exposure to the fungus. These include fatigue, cough, fever, shortness of breath, headache and muscle aches and pains. The usual treatment is a three-to-six-month course of an antifungal medication like fluconazole. For people with severe infections that affect the lungs, treatment may be longer and require hospitalization.

In California, climate change is contributing to greater swings between intense precipitation and prolonged dry weather, says the Times. This can cause ‘superblooms’ of the fungus, notes Morgan Gorris, a scientist at Los Alamos National Laboratory in New Mexico who is an expert on the effects of climate patterns on human health.

She said that warming and drying trends driven by climate change “could allow more of the western United States to be able to host this fungus. So ultimately, the fungus may spread, and it may put more people at risk for contracting Valley fever.”

The disease can affect animals, including pets, as well as humans. It has killed the gorillas at both the San Francisco and San Diego zoos. Experts are working toward developing a vaccine and other ways to reduce the spread. Face masks worn during the COVID-19 pandemic helped keep the numbers of valley fever low by protecting people from inhaling spores.

Health officials say awareness is critical because many clinicians have not heard of the disease and don’t know how to test for it. Some cases may also be misreported as COVID-19 because they share similar symptoms.

“Even if you aren’t in what’s considered a classic endemic location for valley fever, but you’re in the northwest, still think about it,” said Crum. “Because you may be the first case diagnosed in your state or in your community.”