While the effects of the increase in global temperature are already causing episodes of intense droughts, floods and increasingly extreme fires around the world, this ecological crisis could soon result in the appearance of new epidemics, further destabilizing public health, which has already shown its fragility during the Covid-19 pandemic. In California, at As the climate crisis dries up the landscape, the number of recorded cases of “valley fever”, a fungal disease, is increasing sharply. However, this proliferation of pathogenic fungi can turn into meningitis, a fatal disease for humans.
In 2012, Rob Purdie contracted a severe form of “valley fever”. After violent headaches, this constant migraine was then coupled with a strong cough, chest pain, sinus infection and shortness of breath. After long months of convalescence, this American is now coordinator of patients and the development of remission programs within the Valley Fever Institutein California.
“This patient had a huge impact on my family and my health. We lost everything, all of our financial security and all of our retirement,” he told the Guardian.
Ten years after the first contractions of this unusual disease, California could soon face an epidemic of valley fever whose development and spread are greatly favored by the effects of climate change. This disease could, according to experts, spread throughout the American West.
Valley fever, or coccidioidomycosis
Valley fever, or coccidioidomycosis, is a fungal disease endemic to the southwestern United States. The disease can be contracted by simply breathing in the spores of the coccidioide, a fungus whose pathogen spores can travel up to 80 km from where they hatch.
Coccidioids grow in soil as filaments that segment and break if disturbed. Thus, pathogen spores may never be released. However, simple archaeological excavations, the presence of a burrowing animal, agricultural activities or urbanization activities can participate in releasing the spores responsible for the disease.
To survive, these fungi need warm and dry climatic conditions. California thus offers a perfect climate for their proliferation. According to Morgan Gorris, a researcher at the Los Alamos National Laboratory and an expert on the relationship between the climate crisis and Valley fever, as temperatures warm and precipitation patterns change, altered disease dynamics may manifest.
“There are already more cases of valley fever today. Much of the western United States is already very dry. When we look at climate change projections we expect these drought conditions to settle in the long term, which will favor the development of cases of valley fever. », she warns.
According to a recent study published by Gorris in the science magazine Geo Health, the areas endemic for the coccidioide will change considerably over the next few years. By 2100, under a high global warming scenario, endemic areas will double, increasing the number of affected states from 12 to 17, including states bordering Canada, and the number of Valley fever cases by 50%.
An expansion already observed
Kern County north of Los Angeles, where Rob Purdie lives, has seen a substantial increase in cases over the past decade. From 2014 to 2021, the number of Valley Fever cases increased by 1,000 to 3,000 according to data from the Valley Fever Institute.
In Arizona and California, no less than 20,000 cases were reported to the US Centers for Disease Control and Prevention (CDC) in 2019et an average of about 200 deaths per year is recorded since the early 2000s.
Finally, unsurprisingly, people working outdoors are most at risk of contracting this respiratory disease. Last summer, following new episodes of devastating fires around the Tehachapi Mountains in southeastern California, three firefighters developed a severe form of the disease.
The rise of these “new diseases” reminds us of the extent of the unsuspected consequences of global warming, and the importance of climate change mitigation for the future of public health.
W.D.
