Climate change may make mushrooms more dangerous to humans

Higher environmental temperatures can cause mutations in fungi that lead to increased infectivity, more aggressive growth, or resistance to multiple anti-fungal medications.

Public health officials have long been concerned that rising temperatures on Earth could cause fungi to become more harmful to humans. Oh, sure, some people get ringworm or nail infections, and some women get yeast infections all the time, but other than those cases, yeast infections haven’t been terribly 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 disturbing evidence suggesting that, as the planet warms, fungi may actually become more common. dangerous to humans.

Mammals are usually naturally protected from most fungal infections because fungi are cold-adapted organisms that grow best at temperatures that are cooler than those found in and on the bodies of mammals. As a result, fungi cause much less disease in mammals than bacteria and viruses. But infectious disease experts have warned that the fungi have the potential to adapt to rapidly warming climate temperatures and may thus reach a point where they can live in and on the human body.

To see if this transition is already happening, researchers working in China looked for fungal infections in patients in 96 hospitals in that country between 2009 and 2019. Among the thousands of pathogenic fungi they isolated and examined, they found one fungus that had never been before. reported to infect humans. pathogen, Rhodosporidiobolus fluvialiswas isolated from the blood of two unrelated patients being treated for severe underlying diseases 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. pathogen was resistant to the two main drugs used to treat potentially fatal fungal infections in humans, caspofungin and fluconazole.

To further characterize this fungal pathogen and demonstrate that it can infect mammals, the researchers injected it into laboratory mice with compromised immune systems. Amazingly, the fungus thrived and some of the fungus cells even changed into a more aggressive form.

When researchers investigated the cause of R. fluvialisincreased pathogenicity, they found that cells cultured at 37°C (human body temperature) developed mutations 21 times faster than cells cultured at 25°C. Further, the researchers also found that R. fluvialisIt developed drug resistance much faster when cultured at 37°C and exposed to another common antifungal drug, amphotericin B.

This is deeply disturbing. Considering the increasing use of immunosuppressive medications in recent decades and the ongoing HIV epidemic, there are more immune-compromised individuals in the general population who are at increased risk for fungal infections. Furthermore, because fungi undergo increased mutation rates in warmer environments—including the higher body temperatures of mammals—this can cause fungi to mutate so that they become more infectious and resistant. to medicines.

Consistent with this finding, epidemiologists have reported that many new fungal diseases are emerging in humans and that at least some of these new pathogens are already drug-resistant.

These are unexpected findings and point to potentially catastrophic health consequences for humans and other mammals if the planet continues to warm.

Source:

Jingjing Huang, Pengjie Hu, Leixin Ye, Zhenghao Shen, Xinfei Chen, Fang Liu, Yuyan Xie, Jinhan Yu, Xin Fan, Meng Xiao, Clement KM Tsui, Weiping Wang, Yingxing Li, Ge Zhang, Koon Ho Wong, Lei Cai, Feng-yan Bai, Yingchun Xu & Linqi Wang (2024). Drug resistance and hypervirulence in a human fungal pathogen is enabled by mammalian body temperature-induced mutagenesis, Nature Microbiology | doi:10.1038/s41564-024-01720-y

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