Climate Change Could Make Fungi More Dangerous To Humans

Public health officials have long been concerned that rising temperatures on Earth could trigger fungi to become more harmful to people.

Oh, sure, some people get ringworm or nail infections, and some women repeatedly get yeast infections, but other than those instances, fungal infections have not been exceptionally problematic. This, however, is changing.

An international team of medical researchers and infectious disease specialists based in China collaborated with a researcher from Singapore and another from Canada, and together, they found troubling evidence suggesting that, as the planet warms, fungi could indeed become more dangerous to humans.

Ordinarily, mammals are naturally protected from most fungal infections because fungi are cold-adapted organisms that grow best in temperatures that are cooler than those found in and on the bodies of mammals. As a result, fungi cause far fewer diseases in mammals than do bacteria and viruses. But infectious disease experts have been warning that fungi have the potential to adapt to rapidly warming climactic temperatures and thus, could reach a point where they can live in and on the human body.

To see if this transition is already occurring, researchers working in China looked for fungal infections in patients in 96 hospitals in that country between 2009 to 2019. Amongst the thousands of pathogenic fungi they isolated and examined, they found one fungus that had never before been reported to infect people. The pathogen, Rhodosporidiobolus fluvialis, was isolated from the blood of two unrelated patients undergoing treatment for serious underlying illnesses in intensive care units: an 85-year-old woman from Tianjin who died in 2016 and a 61-year-old man from Nanjing who died in 2013. The pathogen was resistant to the two main drugs used to treat potentially fatal fungal infections in humans, caspofungin and fluconazole.

To further characterise this fungal pathogen and to demonstrate that it could infect mammals, the researchers injected it into lab mice with compromised immune systems. Surprisingly, the fungus thrived and some of the fungal cells even mutated into a more aggressive form.