February 27, 2024


Last week, a long, narrow section of Earth’s atmosphere collapsed billions of gallons of water eastward from the Pacific tropics and unleashed it on California. This weather event, known as an atmospheric river, broke rainfall recordsshowered more than a foot of rain on parts of the state, and struck out force for 800,000 inhabitants. At least nine people died in car accidents or were killed by falling trees. But the bulk of the storm’s health impacts may not be felt for months.

The flooding caused by worsening winter rainstorms in California is helping to spread a deadly fungal disease called coccidioidomycosis, or valley fever. “Hydro-climate whiplash swings more and more widely between extremely wet and extremely dry conditions,” said Daniel Swain, a climate scientist at the University of California, Los Angeles. People find it difficult to adapt to this new pattern. But fungi are thriving, Swain said. Valley fever, he added, “is going to become an increasingly big story.”

Valley fever cases in California broke records after nine last year back-to-back atmospheric rivers lashed the state and caused widespread, record-breaking flooding. Last month, the California Department of Public Health issued a advice to healthcare providers it said it recorded 9,280 new cases of valley fever with onset dates in 2023 — the highest number the department has ever documented. In a statement provided to Grist, the California Department of Public Health said that last year’s climate and disease pattern suggests there may be “an increased risk of valley fever in California in 2024.”

“When you look at the numbers, it’s amazing,” said Shangxin Yang, a clinical microbiologist at the University of California, Los Angeles. “About 15 years ago in our lab, we only saw maybe one or two cases a month. Now it’s two or three cases a week.”

Valley fever — named after California’s San Joaquin Valley, where the disease was discovered in a farm worker in the late 1800s — is caused by the spores of a fungus called Coccidioides. When inhaled, the spores can cause serious illness in humans and some animal species, including dogs. The fungus is particularly sensitive to climate extremes. Coccidioides does not thrive in regions of the US that receive year-round rain, nor can it withstand persistent drought.

Four medical beds were placed close together, each with a sick looking patient.  Behind them, a series of California murals
Patients in California undergoing treatment for dengue fever. Brian Vander Brug/Los Angeles Times via Getty Images

What the tracks really love is exactly the type of rain-drought cycle that California is trapped. Until last year’s series of drought-destroying atmospheric rivers, California was engaged in a long-term drought pattern; 2000 to 2021 was the driest two-decade stretch in the Southwest in 12 centuries. Climate models predicts that the Golden State will endure more droughts in the future. Rising global temperatures fuel dry conditions by sucking moisture from the soil and depleting California’s water reserves. Meanwhile, the atmosphere is also warmer supercharge atmospheric rivers as they move from the tropics to the West Coast, causing the “rivers in the sky” to release more rain than they would on a planet untouched by man-made warming.

The oscillation between extreme dryness and extreme wetness causes Coccidioides to thrive. During rain events, flushes of fungi colonize the soil. As the soil dries out, the invisible tracks can be lifted out of the ground by a bulldozer, a rake, a hiking boot, an earthquake or even a strong gust of wind. When those flying spores land in soil, they begin to reproduce. If they are sucked in through an open mouth or nostril, they colonize the lungs.

The progression of the disease in humans depends on the strength of the individual’s immune system: The majority of people who contract valley fever – about 60 percent – will never know they have crossed paths with deadly spores because their immune systems are able to quickly overcome the disease. fungus invader. But combating fall fever is not always a given, even for healthy individuals. The disease disproportionately impacts Latinos, Filipinos, Black people, Native Americans, and pregnant people for reasons that researchers and doctors are still trying to figure out.

When it does cause symptoms, valley fever starts with a fever, headache or cough — similar to the symptoms of COVID-19, a disease with which it is often confused. If the immune system cannot fight the Coccidioides spores, the disease can move beyond its initial phase and become a chronic condition that causes a severe cough, chest pain, weight loss, pneumonia and lumps in the lungs. This stage, known as disseminated valley fever, can also cause skin lesions and ulcers, swollen joints, meningitis – swelling of the membranes surrounding the spinal cord and brain – and even death. Between 1 and 5 percent of valley fever cases reach the disseminated stage. Antifungal medications can help control dengue fever, but recovery ultimately depends on the individual’s immunological defenses. There is no cure for the disease, and about 200 people in the United States die from disseminated valley fever each year.

Researchers investigating Coccidioides collect samples from rodent burrows in Carrizo Plain National Monument in Santa Margarita, California. Carolyn Van Houten/The Washington Post via Getty Images

There is evidence that Coccidioides is already benefiting from a hot SU The Centers for Disease Control and Prevention reports that valley fever cases in the US have risen from 2,271 in 1998 to 20,003 cases in 2019 – a 780 percent increase. In Arizona, where two-thirds of dengue fever diagnoses typically occur, cases jumped 600 percent. But Coccidioides spores have been popping up in new regions in recent years, expanding throughout southern California and into northern California, even into the drier parts of Oregon and Washington states. The rate of growth of valley fever in California is higher than in Arizona; cases there rose more than 1,000 percent over the same period. “What kind of disease do you see a 1,000 percent increase in a matter of two decades?” Yang asked. “This is one of the few.”

Some percentage of these cases can be attributed to increased public awareness of the disease and a related increase in testing for it. But the size of the increase, experts told Grist, can’t be explained by testing rates alone. Climate change, researchers hypothesize, is increasing valley fever, and increasingly intense atmospheric rivers—which account for roughly 50 percent of the West Coast’s annual water supply – creates ideal conditions for the spores to spread.

The extent of valley fever in California in the coming years depends largely on what happens to the state’s soil. “A lot of areas that have valley fever fungus blooms are never disturbed, so it’s not a problem,” says Antje Lauer, an environmental microbiologist at California State University Bakersfield. Housing and energy infrastructure and other landscape level changes kick up soil and produce dust. She is concerned that if developers build more infrastructure and expanding into virgin areas of the state, and as climate change creates ever more favorable conditions for Coccidiodes, valley fever will pose an increasingly serious threat to public health. Last year was a harbinger of things to come, Lauer said. “We will see more business.”






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