Two new studies have shown how climate change can increase disease. Both of these reports were focused on recent increases in cases of coccidioidomycosis, also known as valley fever. The first study was published in JAMA Insights. These researchers noted that 2023 had the highest recorded number of valley fever cases ever in the state, with 9,210 confirmed. The other report was published in Environmental Health Perspectives, and it determined that in regions where there are higher levels of fine mineral dust in the air, there are also higher rates of valley fever. These study authors noted that the findings highlight how dust exposure can increase disease risk.
Research reported in The Lancet in 2022 showed that increased transmission of valley fever happened after multi-year cycles of drought followed by wet winters. This work has now been confirmed. Droughts can also cause more dust to move into the air, which increases valley fever risk too.
Valley fever is caused by the fungus Coccidioides immitis, which is often found in soils in the southwestern United States and in some parts of parts of Central and South America. The fungus or its spores can be thrown into the air when soils are disturbed, such as by wind or construction.
Valley fever can arise when spores of this fungus are inhaled, and the illness may cause fever, fatigue, headache, cough, chest pain, and skin rash; symptoms are thought to arise in about 40 percent of infections. Most people recover from the illness on their own, but it's estimated that ten percent of those infected develop more serious problems like pneumonia, blurred vision, or confusion. Valley fever cannot spread from one infected person to infect another.
The infection can usually be diagnosed by testing for antibodies to the fungus.
The high incidence of valley fever in California in 2023 occurred after a series of atmospheric rivers led to major flooding. The central region of California received one year's worth of precipitation in under one month. But this happened after a prolonged period of drought. This hydroclimate whiplash seems to have boosted the growth and spread of the Coccidioides immitis fungus.
“If you look at the numbers, it’s astonishing,” 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.”
People can reduce their risk of contracting the illness by wearing an N95 mask, and keeping their windows closed during dust storms. Air filters can also reduce the risk. Ultimately, it will also be important to address climate change and reduce the burning of fossil fuels if we want to stop the increase in valley fever, or other illnesses such as malaria that are spreading to new areas because of shifts in the climate.
Sources: Environmental Health Perspectives, The Lancet, JAMA Insight