HBO's The Last of Us depicts a "zombie fungus" which has led the world into ruin. Unlike the typical monster-like zombies often depicted in media, the zombies in The Last of Us have been infected by a fungus that takes control of people's bodies and minds. The creepy infections and resulting dystopia have many viewers wondering: how realistic is this scenario and could this potentially happen in real life? Here's everything you need to know:
Is there such a thing as a 'zombie fungus?'
Actually, yes. The fungus from the show and video game, which the series derived from, is based on a real-life fungus that affects ants called Ophiocordyceps unilateralis. "Like something out of science fiction," David Attenborough described it in a 2006 episode of Planet Earth, "the fruiting body of Cordyceps erupts from the ant's head."
The fungus makes ants climb trees, dangle from branches and then shower spores all over the forest, writes CNN. It is one of the most well-known organisms with a "mind control" ability, according to NPR. "There seems to be some combination of physical manipulation of muscle fibers, for example, possibly growth into the brain itself, that can impact [insect] behavior," explained Bryn Dentinger, a biology professor at the University of Utah. "But there's also very likely some sort of chemical attack on the host, either small molecules, or proteins or some other things, that end up manipulating brain behavior."
Can it infect humans?
There are currently 100 known Ophiocordyceps species that have the ability to infect a number of insects, however only 35 have been found to have the ability to take control of the insects' minds and bodies, CNN writes. Relievingly, none have been found to be able to infect humans.
João Araújo, an assistant curator and researcher in mycology at the New York Botanical Garden, said it's "very unlikely" that the fungus would be able to infect humans. The Cordyceps are "not prepared to invade, establish within and transmit spores from a human body," and "cannot even establish themselves in any mammals or non-insect animal," Araújo told Forbes.
This is largely because of the massive difference in physiology between insects and humans. "They're super species-specific," explained Charissa de Bekker, an assistant professor at Utrecht University in the Netherlands. "They have very refined machinery to interact with their hosts and do these really interesting things like changing behavior, but they can't even jump from one species to the next."
Are there fungi affecting humans?
Human's high body temperatures make the Cordyceps incapable of affecting humans, but there are other fungi that are adapted to those higher temperatures. "That may be one reason why we're seeing more fungal infections in ... humans," Dentinger said. Scientists estimate that there are approximately 1.7 million deaths per year attributed to severe fungal infections. Some fungi like "magic mushrooms," usually consumed recreationally, act as psychedelics, impacting the human mind.
Climate change is also pushing fungi to adapt to survive in warmer environments. "If their optimal growth temperatures, therefore, become higher and closer to our body temperatures, it might be more likely that in the future, we have more fungal infections in humans than we see right now," remarked de Bekker.
While the chances of a zombie apocalypse are low, fungal infections are a growing concern. A particularly deadly one, Candida auris, is highly contagious and doesn't respond to treatment. It has been found in 30 countries. In general, fungi are more difficult to treat because their cells are similar to the cells in humans. It's difficult to find a treatment "that targets the fungus and not the humans," says to Dimitrios Kontoyiannis of the University of Texas MD Anderson Cancer Center's Medical Mycology Research Center.
Could the world see a fungal pandemic?
The consensus is that while not impossible, it is highly unlikely. Fungi don't spread the same way as bacteria or viruses and require skin-to-skin contact in most cases, writes The Hill. Unlike viruses, fungi don't necessarily need a host to survive.
Those who are immunocompromised or already have underlying chronic health conditions are more susceptible to fungal infections, according to a report by the World Health Organization. There are currently 19 fungal diseases that are threats to humans.
In general, climate change is making the world more susceptible to pandemics and the world is unprepared to handle a potential fungal outbreak. "We really only have three classes of drugs to treat severe fungal infections," said Tom Chiller, chief of the Mycotic Diseases Branch at the Centers for Disease Control and Prevention. "But what if a particular strain is resistant to all three? We do have drugs in development, but we need a lot more."
David Hughes, one of the scientists who was consulted during the creation of The Last of Us, described it as a "real-time study in what we pay attention to and what we act on."