Spread of fungal lung disease may be due to climate conditions
Fungal lung infections are spreading to parts of the United States where they were once never seen — likely a result of climate change, experts say.
To the average person, the term fungal infection may conjure up thoughts of athlete’s foot or toenail problems. But some fungus species cause potentially severe respiratory infections, when a person inhales microscopic spores from fungi in the soil.
In the U.S., the major fungal species behind those illnesses were historically limited to regional “hot spots.” But that’s no longer the case, according to Dr. George Thompson, a professor and infectious disease specialist at the University of California Davis School of Medicine.
Writing in Annals of Internal Medicine, Thompson and colleague Dr. Tom Chiller, of the
U.S. Centers for Disease Control and Prevention, describe the expansion of three fungal diseases: histoplasmosis, blastomycosis and coccidioidomycosis (commonly called Valley fever).
Each was once confined to specific areas of the country. Now, Thompson said, more than 10% of the infections occur outside of their traditional ranges.
Valley fever was historically confined to California and the southwestern U.S. But the disease is expanding north — with cases turning up in Washington state a decade ago, for instance — and eastward.
Histoplasmosis, meanwhile, used to be a disease of the Midwest and parts of the East. Now cases are being diagnosed throughout much of the country.
Exactly why fungal infections are spreading is unclear, but Thompson and Dr. Andrej Spec, a fungal infection specialist at Washington University School of Medicine in St. Louis, pointed to climate change as a prime suspect. Fungi need certain conditions to thrive, and changes in rainfall and soil could be fueling the spread of the species that cause lung infections. Spec also pointed to a role for bat migrations; bats commonly carry fungal pathogens, and can deposit them in the soil through their droppings.