Fungi can be wonderful. Penicillium molds produce the antibiotic penicillin, which has saved untold lives by warding off bacterial infection. Psychedelic mushrooms alter the mind in profound and psychologically beneficial ways.
But fungi have a dark side, too. Many parasitize and zombify other creatures, hijacking their bodies for gruesome, self-interested purposes — fortunately, humans have not yet made the list.
Others, in stark contrast to penicillium, can cause severe infections. Here’s a selection of the weirdest, grisliest, and most concerning fungi.
1. Cordyceps Fungi
An ant infected with Cordyceps. (Image Credit: Jojo dexter/Shutterstock)
Perhaps the best-known of the scary fungi, cordyceps recently got a big boost in publicity from The Last of Us, a post-apocalyptic video game turned HBO series. The premise is that a fungal epidemic upends the world, turning the infected into zombies with mushrooms for faces.
It’s a terrifying idea, made even more terrifying by its basis in reality: What the show portrays cordyceps doing to people, they actually do to ants. Once cordyceps fungi infect a host, they manipulate its behavior for the sake of their own survival and reproduction. Controlling the ant’s every movement, the fungus forces it to climb to a high place, clench down on a leaf, and hang there until it dies.
It gets worse. A few days after the ant dies, the cordyceps-driven mission finally becomes clear: Long, stalk-like fruiting bodies begin to sprout from the poor creature’s body. Soon, from this convenient perch, they release spores far and wide, spawning a new generation of ghastly parasites.
There are about 750 known species of cordyceps worldwide. They live in almost every region, including North America, but are most abundant in humid temperate and tropical parts of Asia.
Luckily, cordyceps don’t infect humans, so we have nothing to fear from them (except nightmares). And although some “zoonotic” diseases have evolved to spread between animals and humans, experts say it’s unlikely cordyceps will make that leap. In fact, they can even help us: one species of cordyceps has been used as a traditional medicine in China for thousands of years, and others are used to control insect pests.
Read More: How a Zombie-Ant Fungus Can Infect a Host
2. Spider Zombie Fungus (Gibellula attenboroughii)
(Credit: CABI).
The new fungus Gibellula attenboroughii on the orb-weaving cave spider
As it turns out, ants aren’t the only ones vulnerable to zombification — there’s another family of zombie fungi that targets spiders. Biologists have known about these fungi for decades, but a new species was discovered in Ireland in 2021, during filming for the BBC Winterwatch TV series. It was named Gibellula attenboroughii after Sir David Attenborough, the renowned British naturalist.
Like cordyceps, Gibellula somehow manipulates its victims, causing them to “exhibit behavioural changes similar to those reported for zombie ants,” according to the authors of a recent paper announcing the new species. The fungus lures the spider out of its web to a place that’s better suited for spore dispersal (the BBC found their specimen on the ceiling of an abandoned gunpowder store). Once the spider dies in that exposed position, stalks shoot forth from its body, and the process begins anew.
3. Cicada Zombie Fungus (Massospora cicadina)
(Credit: Gerry Bishop/Shutterstock)
We’re not quite done with zombies. Massospora cicadina targets male periodical cicadas — which emerge from underground for a short breeding season every 13 or 17 years — and it has the most ingenious strategem of all.
Under fungal influence, infected hosts flick their wings in precisely the same way as sexually receptive female cicadas. The display attracts other males from far and wide. But unbeknownst to these would-be suitors, the host’s lower abdomen has been eaten away by the fungus and, rather horrifically, replaced by a plug of spores. As the cicadas attempt to mate, they become infected by the spores themselves.
4. Candida auris
Microbiological culture of the yeast Candida auris. (Credit: TopMicrobialStock/Shutterstock)
When the World Health Organization released its first list of threatening fungal pathogens in 2022, Candida auris was one of just four in the “critical” category. In recent years, this multi-drug-resistant fungus has spread alarmingly throughout healthcare facilities.
A kind of yeast first reported in the U.S. in 2016, C. auris can cause life-threatening infections that are difficult (if not impossible) to treat. Clinical cases have risen year after year; in 2023, the number reached more than 4,500 nationwide. C. auris remains almost nonexistent in some regions, but California, Illinois, Florida, New York, Texas, and Nevada have all been hit hard. And it’s still winding its way across the rest of the country — just last recently, health officials in Montana confirmed their first case.
Symptoms depend on where the infection takes root, from the skin to the bloodstream. They can resemble a bacterial infection, with fever and chills, but there’s no common set of symptoms, according to the Centers for Disease Control and Prevention. Otherwise, healthy people typically don’t get sick.
Though C. auris can spread through the air — usually only short distances — it’s primarily spread by direct contact. The fungus colonizes surfaces, like tables, doorknobs, bedrails, and even human skin, and can survive on these objects for a long time.
5. Aspergillus Fumigatus
(Image Credit: M-Production/Shutterstock)
Besides C. auris on that list of fungal threats, also in the critical category, is Aspergillus fumigatus. For years, it too has been developing resistance to antimicrobial drugs, possibly as a result of agricultural fungicide use (though some studies dispute that idea).
A. fumigatus is a common mold normally found in soil, where it grows on decaying vegetation. It doesn’t infect most people, but can cause a life-threatening illness, called invasive aspergillosis, in those with lung disease or weakened immune systems. Symptoms range from fever and chest pain to shortness of breath and coughing up blood.
Some people who aren’t immunocompromised might still have an allergic reaction to A. fumigatus, with symptoms like wheezing, coughing, and shortness of breath. Though not as severe as aspergillosis, these reactions can cause damage to the airway and lungs, especially in people with asthma.
Read More: New Zombie Fungus Is Infecting and Killing Spiders in Irish Caves
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Cody Cottier is a contributing writer at Discover who loves exploring big questions about the universe and our home planet, the nature of consciousness, the ethical implications of science and more. He holds a bachelor’s degree in journalism and media production from Washington State University.
