Super-fungal infections could cause famine due to becoming resistant to treatments

Monday, 21st May 2018, 9:29 am
Updated Monday, 21st May 2018, 12:21 pm

Common fungal infections could threaten pestilence and famine because they are becoming resistant to treatments, a new study warned.

Like the increasing number of bacteria that are antibiotic resistant, fungal infections in crops, animals and human could one day become incurable.

This would cause widespread crop failures and could be deadly for those with underlying conditions such as weakened immune systems from having cancer or an organ transplant.

The international team led by researchers from Imperial College London and the University of Exeter warned this growing levels of resistance to antifungal treatments was "under-recognised and under-appreciated."

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They blame the overuse for the unprecedented rise in emerging strains of fungi which are resistant to common antifungal drugs.

And global trade, migration of people and animals and food was also helping resistance to spread rapidly.

Fungal threat

First author Professor Matthew Fisher, from Imperial's School of Public Health said: "The threat of antimicrobial resistance is well established in bacteria, but has largely been neglected in fungi

"The scale of the problem has been, until now, under-recognised and under-appreciated, but the threat to human health and the food chain are serious and immediate.

"Alongside drug discovery and new technology to tackle fungal pathogens, we urgently need better stewardship of existing antifungals to ensure they are used correctly and that they remain effective.

"Fungi are a growing threat to human and crop health as new species and variants spread around the world, so it is essential that we have means to combat them.

"However, the very limited number of antifungal drugs means that the emergence of resistance is leading to many common fungal infections becoming incurable."

The review paper published in a special edition of the journal Science said fungal pathogens are responsible for a broad range of infections in humans, animals and plants.

Crop catastrophe

These include blights which can wipe out food crops, yeast infections which can lead to blood poisoning in humans and livestock, as well as chytrid - the fungus responsible for the 'amphibian plague' wiping out species around the world.

Crop-destroying fungi destroy a fifth of global crop yields each year, and the direct threat to human health is increasingly significant.

The number of human deaths from fungal diseases is estimated to now exceeds those from malaria and breast cancer, and is comparable to numbers of those caused by tuberculosis and HIV.

Like bacteria, fungi are thought to be able to 'swap' genes with one another, helping resistance to spread.

Yet their rapid rate of reproduction means resistant strains can quickly increase their number.

In terms of food production, intensive farming practices along with cultivation of relatively few crop species and overuse of existing chemicals to keep them free of disease, have driven resistance.

Professor Fisher explained: "The emergence of resistance is leading to a deterioration in our ability to defend our crops against fungal pathogens, the annual losses for food production has serious implications for food-security on a global scale."

He adds fungicides used in agriculture are also leading to the emergence of antifungal resistance in human fungal pathogens.

Resistance is fungal

The widespread use of one group of AFDs in particular, a class of antifungals called azoles - discovered in the 1950s and used to treat yeast infections - are cited as a key driver in the emergence of resistant strains of fungi.

Azoles are believed to account for a quarter of fungicides used in agriculture, but they are also used as first line antifungals in the clinic.

Their widespread use is thought to be increasing antifungal resistance, by selectively killing off non-resistant strains, with those more resistant to the fungicides remaining.

The danger for human health is when this resistance occurs in species such as Aspergillus fumigatus - moulds which thrive on decaying vegetation but are also able to infect those with compromised immune systems, such as cancer patients or those who have received organ transplants.

As well as more selective use of existing antifungals, and focusing on the development of new drugs, treatments aimed at silencing the genes of fungi and stopping them from spreading could help to tip the balance in the fight against fungal pathogens.

Professor Sarah Gurr, from the University of Exeter, said: "Emerging resistance to antifungal drugs has largely gone under the radar, but without intervention, fungal conditions affecting humans, animals and plants will become increasingly difficult to counteract."