ATTACK OF THE KILLER FUNGUS

Mention a fungal infection and most people will think of athlete’s foot, but the reality is that they kill more people than breast cancer or malaria every year. Jane Symons asks the experts about the latest developments in the war on spores

It might sound like a bad science fiction film from the 1960s, but the reality is that fungal infections now kill four times more people than malaria – and they are becoming increasingly dangerous.

Globally, there are more than 150 million severe cases of fungal infections and 1.7 million deaths annually, and those numbers are rising steadily because infections caused by yeasts and moulds are becoming more difficult to treat.

As we have already seen with bacterial resistance and the emergence of MRSA and other forms of drug-resistant staphylococcus, yeasts and moulds are mutating and finding ways to evade the drugs we use to treat them.

But the true scale of the threat was acknowledged only last year, when an international consortium of 29 countries, which is working together to beat all forms of microbial resistance, finally added fungi to its to-do list.

Professor Adilia Warris, an international authority on fungal infections and co-director of the Medical Research Council Centre for Medical Mycology at Exeter University, says: “Fungal infections are very serious, but I think one of the reasons they are not at the forefront of people’s minds is that they often come as a complication on top of another disease.

“Everyone knows how horrible cancer is, but what people often don’t realise is that cancer patients are also at very high risk of developing fungal infections and they are a significant factor in many cancer deaths.”

Similarly, studies show that as many as one in six people who are admitted to intensive care units with Covid-19 also have invasive fungal infections.

Like staphylococcus bacteria, there are fungi such as candida albicans which most of us carry on, or in, our bodies naturally. But like “staph” it is opportunistic, so if the immune system becomes weakened or something causes an overgrowth of candida, it can lead to infections such as thrush, or more serious invasive infections which can affect the blood, heart, brain and other vital organs.

Like candida, aspergillus is rarely an issue in healthy people, but Professor Warris says, “It releases tiny spores into the air, which we breathe in. If the lung is already damaged, someone is already ill, or the immune system is too weak, these spores can grow out in a kind of filament. This can cause an infection with inflammation and you get really bad pneumonia.”

We have only three drugs to treat fungal infections and one form of candida – candida auris – has developed resistance to all three. Aspergillus has also found ways to shrug off the widely used azole family of antifungal drugs.

Professor Warris says: “There are a number of challenges around resistance. As agriculture has been intensified, we are using more antifungals in food production and that has driven resistance.

“These infections are difficult to diagnose and because we don’t have good diagnostic tests, we are treating patients who are at high risk for fungi disease who may not have it.”

Not following the instructions on over-thecounter antifungal remedies, stop-starting treatment or inappropriate use of antifungals also make it easier for fungi to develop resistance to the treatments we have.

Professor Warris says: “We have also been confronted with a new fungal species, which we have discovered in the past 10 years, which is already very resistant to the treatments we have. That is really shocking, because it has just turned up, and we have no answer for it.”

She warns: “We are in danger of getting to a point where these things become completely resistant. We really need to speed up research to get ahead of the game.”

Patients with cancer are at high risk of developing infections