The global burden and death toll of fungi has substantially climbed over the past decade, new research finds. The study estimates that fungal infections help kill nearly 4 million people annually—almost double the amount estimated by similar research in 2012. Co-infections like HIV and tuberculosis, a lack of speedy and reliable diagnostic testing, and growing antifungal resistance are thought to be major contributors to these deaths.
The new research is by David Denning, a fungal infection researcher at the University of Manchester in the UK. Over a decade ago, Denning and his colleagues conducted a review of the available data on the global morbidity and mortality of fungal infections, particularly the infections that can cause severe illness by systemically invading our bodies. Back then, they estimated that fungi directly caused or contributed to the deaths of about 2 million people every year.
In this latest paper, published last week in The Lancet Infectious Diseases, Dennings tried to gauge how common and deadly these infections were between 2019 and 2021. To do so, he reviewed dozens of papers published from 2010 to 2023, ultimately analyzing data collected from over 120 countries.
Dennings now estimates that 6.5 million invasive fungal infections and 3.8 million fungal-related deaths occur worldwide every year. He also calculated that about 2.5 million of these deaths are directly attributable to fungi. For some added background, a recent review estimated that infectious diseases as a whole cause or contribute to roughly 14 million deaths annually.
While people are routinely sickened by viruses and bacteria, fungi are typically less suited to infect us. Most species can’t live for long inside our warm bodies, and our immune systems are usually very capable of resisting fungal infection. But in recent decades, several factors have made these infections more common. New medicines have allowed people to live with donated organs or survive once-fatal conditions, but at the cost of a weakened immune response, for instance. Some scientists also speculate that climate change has helped some fungal species, such as Candida auris, evolve to become heat-tolerant, which then makes it easier for them to infect humans.
Fungal-related deaths that happen today are often linked to other health problems, Dennings notes. For instance, he estimates that over 2 million annual cases and 1.8 million deaths of invasive aspergillosis—infections of Aspergillus fungi that typically affect the lungs—occur in people who are struggling with chronic obstructive pulmonary disease, lung or blood cancer, tuberculosis infection, or who are otherwise in intensive care. Fungal infections in general are also estimated to contribute to nearly half of the 600,000 deaths that still happen every year from poorly controlled HIV/AIDS. And it’s possible that Denning’s tally is an underestimate, since he didn’t look at the potential impact of the covid-19 pandemic, which is known to have helped spark large outbreaks of fungal germs inside hard-hit hospitals.
Many of these deaths may have been preventable if doctors were better at proactively recognizing fungal disease, Dennings says. But current diagnostics often fail to detect these infections even when doctors suspect their presence, he adds. We also have relatively few antifungal drugs available, and some germs have quickly learned how to defeat these treatments.
Scientists are working on developing new drugs and other avenues of prevention, such as vaccines. But Dennings says more accurate and readily available tests are also needed to help contain the growing fungal threat to humanity.
“Severe fungal disease strikes when people are already ill, with only a few exceptions in healthy people and in those living or working in moldy homes or work environments. That is why accurate and timely diagnosis is desperately needed, and why we need to take fungi very seriously,” Dennings said in an article discussing his new research published in The Conversation.