Fungal infections are ‘taking over the world'. Can they be stopped?

Telegraph

07-04-2025

Blood congealed 'like black sausage', sexually-transmitted athlete's foot, and bloodstream-born pathogens untreatable with existing drugs. These are the kinds of fungal infections Professor Darius Armstrong, Infectious Diseases and Medical Mycology at Imperial College London, is used to treating.
'Probably about a third of the world is infected by some kind of fungus,' says Prof Armstrong, 'mostly skin, mucocutaneous, vaginal candidiasis, athlete's foot. Those kinds of fungi that aren't deadly but they are increasing in resistance'.
More lethal fungal varieties are spreading too: invasive fungal infections are killing an estimated 2.5 million people each year – twice the global fatalities of tuberculosis.
The world remains critically underprepared for fungal infections, the World Health Organization (WHO) warned this week, with a lack of diagnostic tests, effective treatments, and surveillance creating an urgent need for research.
But how serious is the problem?
The WHO's fungal priority pathogens list, compiled in response to this rising public health threat, is an itch-inducing read.
'Critical priority' fungi with mortality rates of up to 88 per cent take the top spots.
'Black fungus' or Mucormycosis, which turns tissue into black lesions, made headlines during the Covid-19 pandemic when 51,000 cases were reported in India.
'It invades very often through the nose, and then it can get into the eyes […] down the optic nerve into the brainstem and kills you,' Prof Armstrong told the Telegraph.
'We have to give [patients] all the strongest drugs we can find…cut out all of the infected tissue which often means major surgery to the face and half their brain'.
For some patients, the amount of blackened tissue that needs removing is so extreme it's impossible and they die within days.
Yet Mucorales, the fungal family which causes Mucormycosis, is not one considered 'critical' by WHO ranking.
There are four invasive fungal pathogens deemed 'critical' on the list, and their insidious spores can even be found in the UK.
One of them, 'Candida albicans', can be found 'in about half the population inside our guts,' says Dr Rebecca Drummond, Associate Professor in antifungal immunity, University of Birmingham.
Aspergillus, another critical priority pathogen, is in fact so widespread that most people inhale between 100 to 1000 spores every day from the air we breathe.
Even the mould on bread can contain Mucor, a fungus that causes Mucormycosis.
The invasive fungal infection making lungs bleed
So if these threats are so prevalent, why don't we hear about them?
Scientists say it's because those most at risk to fungal pathogens are people with weak immune systems, like patients living with HIV or on chemotherapy.
'Most fungal infections attack people who've already got existing illnesses, so they've either got weakened immune systems or they've got problems with their lungs' Prof Armstrong says. 'Because they don't strike down the man or woman in the street, so to speak, they don't enter into the public folklore in the same way that viruses and bacteria do.'
As medical interventions have improved – think of advances in chemotherapy that have enabled a much greater number of cancers to be treated – there are now more people living with compromised immune systems who are vulnerable to deadly spores.
Grace*, 66, has long suffered from severe asthma. Just over 10 years ago, she was diagnosed with Chronic Pulmonary Aspergillosis (CPA) and Allergic Bronchopulmonary Aspergillosis, a lung-damaging, life-threatening, condition caused by the fungus Aspergillus fumigatus – another of the WHO's priority pathogens.
'I'd get my children to do back patting exercises to try and loosen [the mucus], I'd be on the floor over the cushions trying to be a bit upside down.' Scans finally revealed the extent of the infection.
'One of [the doctors] said: 'We know it's not cancer, because [with] the amount of patches you've got, you wouldn't be here,' she said, referring to the dark blotches of lung damage visible by x-ray.
Cocktails of antifungal drugs made her hair fall out and damaged her liver function.
Now, her lungs bleed daily, 'it's fresh blood, you can just suddenly feel it in your chest'.
Her breathing is inhibited by what she called 'basically a ball of fungus' in her lungs that has taken hold, causing inflammation and pulmonary cavities – small air-filled spaces within the lung tissue.
The fungal strain that is causing Grace's agony is found in soil across the UK, including in her native Wales, and she believes she caught the infection when she moved into her house while it was still being built.
'My doctors asked me at the time: 'Any idea how you've got this?' […] I bet it was moving into a building site, all the earth is being churned up, diggers going past, and dump trucks going past with soil on.'
A decade later, Grace is terrified of catching any further chest infections or bursting a blood vessel.
'My life has become much smaller,' she said.
She relies on daily intravenous antifungal drugs, a treatment so expensive that her doctors had to lobby the Welsh government to sign off on it.
She's adamant that an earlier diagnosis would have helped her.
'If your asthma's getting out of control, if antibiotics aren't really solving the problem, you need to be tested for fungal disease.'
Fungus 'slowly taking over the world'
Fungi have already been pivotal in some of the biggest public health crises of recent decades.
'In Covid, around 10 to 15 per cent of intensive care patients actually had secondary infection with Aspergillus,' says Prof Armstrong, 'for these patients, their risk of death was two to three times higher.'
Just this week, the UK Health and Security Agency (UKHSA) issued a warning of a 'rapidly emerging' fungal pathogen, Candida auris, undetected until 2009, which has now spread into hospitals globally.
'Candida auris is an antimicrobial-resistant pathogen that's slowly taking over the world,' says Prof Armstrong.
The rise of drug-resistant fungi like Candida auris are increasingly concerning for researchers and clinicians, with some scientists describing the phenomenon as a 'silent pandemic'.
Just as bacteria develop resistance to the antibiotics used to treat them if they are overused, so too do fungi adapt to resist drugs, dramatically limiting doctors' ability to treat infected patients.
But experts warn that drug resistance is also an environmental issue.
'Antifungal drugs that we would use in the clinic to treat infections are actually the same types of antifungal drugs that we would use in agriculture to protect plants…there's evidence now that before patients even had an antifungal drug, they're already infected with drug resistant strains, and it's because the fungus has picked up the drug resistance in the environment' Dr Drummond told The Telegraph.
How climate change is fuelling the fungi
Climate change could also be contributing to the problem.
Most fungal species cannot grow above 37 degrees celsius, and some researchers hypothesise that we might have even evolved to have this body temperature to keep fungi at bay.
But experts now fear that rising global temperatures are helping fungi adapt to warmer climates.
'About 99 per cent of [fungi] don't grow anywhere near body temperature… the ones that do grow near body temperature can cause dangerous infections. That's basically the primary rule as to whether a fungus can be a pathogen,' says Prof Armstrong.
'[But] because of global warming, more and more so-called non-pathogenic fungi are spending more and more time adapting to temperatures that could enable them to cause invasive infections in humans'.
Between 2009 and 2019, researchers discovered a fungus at a hospital in China which had never before infected people, but was making two patients sick. It was already resistant to two antifungal drugs.
The fungus, when kept at 37 degrees – the temperature of the human body – mutated 21 times faster than when it was kept at a cooler 25 degrees.
Not only did it thrive at body temperature, but when exposed to heat, its resistance to a third drug increased, leaving it virtually untreatable with existing medicines.
Climate change is also thought to have contributed to an explosion in cases of Valley fever, an infection caused by inhaling fungal spores which grow in soil in the southwestern US, northern Mexico, and parts of Central and South America. Between 1998 and 2015, cases went up 400 per cent, according to the CDC.
The reason for the increase? More dust storms.
The race to find new drugs
So with deadly fungal pathogens that are able to resist our best drugs being spread by climate change, what is needed to counter the threat?
'We don't have a big backlog of new antifungal drugs coming up behind the ones we already have. So once we lose access to these antifungal drugs, if resistance becomes that bad, we're not going to have an awful lot to come up behind it,' says Dr Drummond.
Creating new treatments to kill fungi is also difficult because they are biologically so similar to humans.
'The closest relative to fungi, the fungal kingdom, is us,' says Dr Drummond, 'the biochemistry of the fungal cell is very similar to our cells, which means that if you're trying to find a drug that's going to kill the fungus, you have to be really sure it's not gonna be toxic to us as well.'
Dr Yukiko Nakatani, WHO Assistant Director-General for Antimicrobial Resistance, says: 'Not only is the pipeline of new antifungal drugs and diagnostics insufficient, there is a void in fungal testing in low- and middle-income countries, even in district hospitals. This diagnostic gap means the cause of people's suffering remains unknown, making it difficult to get them the right treatments.'
In the last decade, only four new antifungal drugs have been approved for use in the United States of America, the European Union or China.
As the clinical pipeline struggles to keep pace with growing drug resistance, the WHO warns that an urgent increase in research and development is critical.
Next week, The Last of Us, a television series depicting a post-apocalyptic world in which civilisation has been brought down by a parasitic fungus that turns people into zombie-like creatures, will be back on our screens.
But how close are we to a real fungal pandemic?
Dr Drummond thinks it's unlikely; fungi don't spread between people in the way shown on the show and the Cordyceps fungus it is based on usually prefers insects.
But, she warns, fungal infections 'will cause lots of problems over time if we don't deal with it now'.
*Names have been changed to protect identities