After nearly 20 cases of Valley fever were identified after a summer music festival in California, state health officials are warning that risk from the fungal infection rises in the late summer and early fall.
“We’re preparing for another possible increase in Valley fever cases in the coming months, and we want Californians to know the signs and symptoms to detect it early,” said Dr. Tomás Aragón, the California Department of Public Health director and state public health officer. “If you have a lingering cough and fatigue, please talk to a doctor about Valley fever, especially if you’ve been outdoors in dusty air in the Central Valley or Central Coast regions.”
People and pets can get the infection by breathing in fungal spores in dust from the outdoors containing the Valley fever fungus, according to the California Department of Public Health. The infection primarily occurs in the southwestern US and some parts of Washington state, according to the US Centers for Disease Control and Prevention.
Valley fever, also known as coccidioidomycosis, is not contagious and cannot spread person-to-person. It can take one to three weeks to develop symptoms, such as cough and chest pain, headache and tiredness. The illness can linger for at least a month.
In rare cases, the infection can spread from the lungs to the brain and spinal cord, the skin or the bones and joints, the CDC said.
Health-care providers can test for the disease through a blood sample or a skin test.
The number of infections is growing in California, with at least 9,000 cases reported across the state in 2023 and more than 5,000 preliminary cases reported so far in 2024 as of July 1, the state health department said.
More than a dozen cases of Valley fever were reported among people who attended or worked at the Lightning in a Bottle music festival in Kern County in May. There were 19 people who got Valley fever and eight people were hospitalized, according to the California Department of Public Health.
“Possible causes of this recent increase include winter rains after several years of drought, an increase in soil disturbance activities (including construction) in high-risk areas, and increased disease recognition, testing and reporting. In addition, while most cases of Valley fever in California are reported from the Central Valley and Central Coast regions, cases have been increasing outside of these regions, including in the northern Central Valley and in southern California,” the health department said in a statement.
A recent study published in the journal The Lancet Regional Health, The Americas suggests that climate change may drive case rates and the seasonal patterns of infection.
The researchers examined cases of Valley fever in 17 California counties between 2000 and 2021 and noted that exposure to the fungus is highest between July and September and lowest between February and April based on when cases increased in the weeks that followed exposure.
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“California has a distinct dry season (April–October) and wet season (November–March) each year, and our results show that coccidioidomycosis seasonal peaks occur most often at the end of the dry season. Anomalously wet conditions in the prior wet season as well as anomalously dry conditions during the concurrent dry season are associated with more pronounced seasonal peaks in incidence,” the researchers wrote.
The study says the findings can help inform public health messaging, by explaining “when to avoid particularly dusty environments and dust-generating activities and, when dust exposure is not avoidable, when to use dust suppression techniques, such as wetting soil before disturbing.” People can use N95 masks to prevent inhaling fungal spores.