Climate change heats up fungal threats worldwide

By Priyanjana Pramanik, MSc.Mar 20 2024Reviewed by Susha Cheriyedath, M.Sc.

In a recent review article published in The Lancet Microbe, researchers synthesized what is currently known about fungal adaptations to rises in global temperatures.

Their conclusions indicate that fungi may become more thermotolerant and adapt to erstwhile inhospitable environments even as climate change promotes the emergence of novel pathogens. The effects of these changes will be felt most by socially vulnerable groups, and mitigation requires targeted and sustained collective effort.

Review: Impact of climate change and natural disasters on fungal infections. Image Credit: Sepp Photography / Shutterstock

Climate change and infectious diseases

Pathogenic fungal species have adapted quickly to increasing temperatures and show signs of greater potency and virulence. While most fungi have a low thermal tolerance, which prevents them from surviving mammalian body temperatures, new pathogens like Candida auris are heat tolerant and adapt to human body temperatures.

Concurrently, a decrease in average body temperatures among people in the United States has been observed, possibly due to reduced chronic infections and inflammation alongside better living standards. Thus, climate change may increase fungal pathogenicity in humans by aligning the temperature preferences of fungi and prospective human hosts.

Modifications to fungal ecosystems

Climate change's shifts in weather patterns continue to disrupt ecological systems and shift the global distributions of disease reservoirs, pathogens, and hosts. Models predict that changes to fungal communities will favor the expansion of saprotrophic fungi.

As pathogenic fungi adapt to one environmental stressor, like rising temperatures, they can withstand others, like heavy metals, radioactive isotopes, and pH stress. This allows them to spread through acidic environments and polluted wastelands. The evolutionary pressures exerted by the heat-island effect in urban areas appear to promote faster fungal adaptation.

Contaminated water bodies may be a source of fungal infections and threaten healthcare systems. Many fungi can degrade plastic while being pathogenic to humans, including Aspergillus and some species of mucormycetes. Thus, microplastic accumulation could encourage fungal growth and resistance to antifungals.

Previously, endemic fungal diseases like histoplasmosis and coccidioidomycoses have increased their geographical ranges. Plant pathogens are also increasing and represent a significant threat to food security. While the use of fungicides has increased in farming, there have been reported cases of antifungal resistance.

Fungal outbreaks after natural disasters

Climate change has increased the intensity and frequency of natural disasters worldwide, which may, in turn, trigger fungal disease outbreaks. This can take place through multiple pathways.

Since disasters damage urban areas and natural habitats, they create settings conducive to the growth of fungi and increase the possibility of exposure to fungal pathogens. For example, injuries like lacerations caused during disasters create points of entry for pathogenic fungi, and wounds can be contaminated, leading to infection by mold. Wildfires can also alter pH values in soil and communities of microbes, increasing cases of eye irritation, asthma, fungal disease, and respiratory symptoms.

Fire plumes and storms can carry fungal spores over large distances, leading to the colonization of novel environments. These can lead to increases in respiratory infections, asthma, and inflammation if they are inhaled. Flooding has also been associated with increases in invasive molds and severe fungal infection outbreaks.

However, there are concerns that fungal outbreaks after natural disasters could be underreported. Preventing and mitigating these issues requires ensuring that living areas are adequately ventilated and that affected areas are intensively cleaned.

Affected communities must be educated so that they can avoid persistent exposure to mycotoxins and mold spores. Adequate resources are needed to identify vulnerable populations and provide them with the necessary protection, and funds must also be set aside for continued research and documentation.

Conclusions

As the effects of climate change are felt around the world, mycologists and public health researchers are raising concerns that rising temperatures promote the emergence of novel pathogenic fungi and modify the distribution and spread of diseases.

Some fungi are more thermotolerant than before and are now pathogenic to humans. Other fungal pathogens were confined to specific areas but are increasing their range due to temperature shifts or the dispersal of spores by winds or fire plumes. Traumatic injuries caused by natural disasters can increase fungal infections.

Fungal pests show signs of increased resistance to fungicides even as fungicide use increases to protect agriculture – this threatens public health and agriculture.

This article represents a call to action. Funding is required to mitigate vulnerable communities' risks, launch effective public awareness campaigns, strengthen healthcare systems, and improve access to healthcare. Research and collaborative action are key to identifying ways to manage existing and emerging challenges in a quickly changing world.