The growing threat of fungal infections – and how to mitigate the global impact of disease
As fans await the second series of the TV drama “The Last of Us” airing on Monday, which imagines a world where fungal infections in the brain are creating zombie-like monsters, academics at the University of Exeter have laid out the real threat from fungi, and the potential impact of emerging new strains.
Two linked review papers published in Nature outlined how the complex web of fungi is impacting Earth’s ecosystems – and lays out a roadmap of how the world should respond.
Fungi are a hugely diverse kingdom of ancient organisms. Yet, of the many millions of species estimated to exist on planet Earth, around 95 per cent remain undescribed by science. As such, the huge potential of these microbes remains untapped.
Fungi affect every aspect of our daily lives – they “manufacture” food stuffs, antibiotics, cholesterol-binding drugs, new biomaterials used in building construction and packaging; recycle plant debris and live in association with plant roots in a mutually beneficial relationship. They are experienced international travellers – either hitching a ride on crops and commodities traded and transported across the globe or by releasing their spores with ballistic speeds, some of which ride on air currents over huge distances. Fungi can also be formidable foe. They destroy our crops, rot our houses and cause sickness and disease in animals and humans – causing allergies, superficial skin and body invasive infections – particularly in those with faulty immune systems.
We are now witnessing new problems, as fungi nimbly adapt to higher temperatures and move concert with climate change. They are able to hop onto new hosts and emerge resistance to antifungals, both in crops and in patients and, worryingly, with evidence of crossover of resistance from crops to the clinic in certain pathogenic species.
In two linked papers1,2, the University of Exeter have coauthored articles with a group of world authorities in mycology (Canadian Institute for Advanced Research (CIFAR) Fungal Kingdom members1) and AMR (fAMR UK consortium2) and have described the complex web of interactions in which fungi are evolving and increasingly developing resistance to antifungal drugs and agricultural fungicides. This antifungal resistance threatens both global crop production and human health. The research team has laid out a road map2, calling for a “One Health” approach, which seeks to better understand and improve the interconnectedness of people, animals, plants, and their environment.
Neil Gow, Professor of Microbiology at the University of Exeter’s MRC Centre for Medical Mycology, said: “In recent years, we’ve seen a slew of books, documenatries and TV shows through which people have become more aware of fungi. The “Last of Us is, of course, science fiction. However, research reveals several worrying scientific facts, which needs urgent action to save crops and human lives. Our latest publications take a broad look at the complex web of interactions, highlighting the positive roles fungi play in out ecosystem and their vast untapped potential1, but we also report the massive risk to crops, and the emerging threat of new strains infecting humans for the first time, as fungi adapt and move in concert with climate change.”
Certain fungi can cause catastrophic loss of calorie and cash crops such as, rice, wheat, maize, coffee and bananas. Many of these are grown in vast monocultures, that is hectare upon hectare of genetically unform plants, guarded by one or two inbred disease resistance genes and sprayed with particular classes of fungicides. Whilst such practices have contributed to global food security, they have also hastened the emergence of fungi resistant to such chemistries. Moreover, spraying has led to resistance emerging in fungi present in the soil and on plant debris. This appears to have been the case in Aspergillus fumigatus, which causes serious disease in patients in hospitals and can be deadly to people who have compromised immunity, such as cancer patients. Treatment of such fungal disease is problematic as the fungicides used to control crop disease belong to the same class of the antifungals used in the clinic.
Climate change correlates with the emergence of new fungal pathogens and old fungal foes on new hosts1,2, some of which are highly drug resistant. Researchers report that some of these pathogens evolved recently to cope with periods of high environmental temperature. This has enabled them to survive, colonise and infect humans for the first time. These include multidrug resistant strains of Candida auris, which is difficult to dislodge from hospitals, and terbinafine resistant Trichophyton indotinea which causes aggressive, spreading and contagious skin infections.
Sarah Gurr, Honorary Professor at the University of Exeter, said: “We’re already engaged in a battle to save global crops from disease and so ensure global food security. Fungal infestations cause huge in-field and post-harvest crop losses. We currently rely hugely in fungicides to control such disease and worryingly, fungi are evolving resistance to certain of these the chemicals. We need to raise awareness of the plight of plants to such foes, to the threat of resistance in crops and in the clinic and to embrace new ways to treat our crops, such as multi-target site antifungals and the use of mixtures of chemistries – to dumb down the possibility of resistance emergence, and to generate gene-edited disease resistant crops.
“Our research is now raising global awareness. Our new research has highlighted these burgeoning problems1. Working with colleagues across the world, we have created a road map, which advocates a “One Health” approach, which seeks to better understand and improve the interconnectedness of people, animals, plants, and their environment2.”
Professor Gow concluded: “ The World Health Organisation has recognised the risk to public health of emerging resistance amongst human fungal pathogens and highlights the need for wider collaboration across economic and policy sectors to better address “One Health” aspects of fungal resistance. We need a stronger voice, to better protect our food crops from fungal disease and to recognise that global warming will likely increase the need for sustainable crop production in the face of the growing number of fungal diseases. As humanity’s reliance on antifungal chemicals escalates, we need to build up a wider understanding of the consequences of scaling up their use, if we are to manage the global spectrum of fungal disease effectively and sustainably in future.”
The papers are entitled: – ‘Fungal impacts on Earth’s ecosystems’, published in Nature – ‘A one health roadmap towards understanding and mitigating emerging Fungal Antimicrobial Resistance – FAMR’, published in Nature.
