Worldwide fungal deaths twice as high as previously thought, research shows

Around four million people are dying every year from fungal infections, new research indicates – nearly double the previous global estimate.

The study, published in the Lancet Infectious Diseases journal, says that more than 6.55 million people annually are affected by invasive fungal infections. These lead to more than 3.75 million deaths, of which 2.55 million are directly attributable to fungal disease.

According to the estimate, this means fungal infections account for around six per cent of all global deaths, killing six times more people than malaria, and almost three times as many as tuberculosis.

There are millions of different fungal species across the planet, which humans are regularly exposed to in everyday life. The vast majority of people have immunity to these infections and do not develop disease.

However, such pathogens can be deadly for those with weakened immune systems, such as cancer and HIV patients, who make up a large number of the people dying every year from fungal infections.

The revised global death toll is based on an extensive review of data taken from hundreds of studies published between 2010 and 2023, along with 85 papers on global disease burdens.

It is higher than previous calculations, which suggested fungal infections kill up to two million people each year. 

This estimate failed to take into full consideration those cases of fungal disease that go undiagnosed and untreated because of limited access to diagnostics, the new research said.

Indeed, testing of fungal cultures only identifies about a third of people who actually have a fungal infection, according to Prof David Denning, the chief investigator of the study.

The research also said that deaths among patients with weakened immune systems can be mistakenly attributed to their long-term condition, such as cancer or chronic obstructive pulmonary disease, as opposed to the real cause of their passing: a fungal infection.

However, Prof Denning cautioned that the new estimates were “necessarily crude”. He added: “Many gaps and uncertainties remain.”

Tihana Bicanic, Professor of Infectious Diseases and Mycology at St George’s, University of London, said that she wasn’t surprised by the large number of people killed every year by fungal infections, which have been “historically neglected, compared to the focus on bacterial infections and antibiotics”. Prof Bicanic was not involved in the study.

In 2022, the World Health Organisation (WHO) unveiled a list of priority fungal pathogens, including 19 deemed to pose a significant threat to public health. Of these, four were identified as being of “critical” priority. 

These included Aspergillus fumigatus and Candida albicans – the two most common fungal pathogens globally – as well as Cryptococcus neoformans, which is a particular threat to those with weakened immune systems and is a leading cause of death in people living with HIV.

Aspergillus fumigatus mainly affects the lungs and is responsible for 2.1 million fungal infections annually, according to the study. A further 1.5 million people are estimated to experience a Candida bloodstream infection each year.

Rebecca Drummond, Associate Professor at the Institute of Microbiology & Infection in Birmingham, called the study “important” as it helps to outline the most deadly fungal diseases.

Prof Bicanic said that the report’s findings will hopefully improve awareness of the threats posed by fungal infections and promote the development of diagnostic capabilities.

“We need to direct attention in terms of research and development efforts,” she said.

Separately, recent reports have warned that climate change is accelerating the spread of dangerous fungal infections. 

Many of the fungi that exist in nature are not well suited to humans due to our high body temperature, but global warming is driving adaptations in these pathogens, enabling them to better infect human hosts.

Prof Bicanic meanwhile warned that the overuse of antifungals – which can be used by hospitals in a preventative capacity, such as in the case of bone marrow transplants, and to treat skin infections like athlete’s foot – could also be fuelling the rise of antifungal-resistant infections.

“Unlike antibiotics, we have about three classes of antifungals that we widely use in patients,” she said.

“All this usage is essentially putting pressure on the fungi, allowing them to adapt and become resistant and that is in fact what’s happening now.”

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