MICHELLE WU / DAILY NEXUS

Zombie apocalypses have been portrayed countless times in movies, shows and video games such as “The Walking Dead” and “The Last of Us,” the latter of which was recently adapted into an HBO television series. Fans of “The Last of Us” might be wondering if a zombie apocalypse could ever actually happen in real life. As it turns out, the creators of the 2013 post-apocalyptic video game drew inspiration from a real-life fungus that infects ants and other insects called Ophiocordyceps unilateralis. The parasitic fungus thrives in tropical areas and produces zombified ants, using them as a vessel to infect new victims.

The unsettling method in which Ophiocordyceps unilateralis takes over an ant’s body involves an infection through which the fungus’ spores infiltrate the ant’s exoskeleton. The fungus then grows around the ant’s brain, which allows it to gain control of the nervous system. According to Ian Will, a fungal geneticist at the University of Central Florida, “It’s unclear exactly how it does this, whether by releasing a chemical or altering a bug’s DNA.” As a result, the ant begins to behave erratically and is compelled to leave its colony, descending to an area of greater humidity that facilitates the growth of the fungus. Forced to permanently lock its jaw to a leaf, it is here that the ant finally meets its fate. After the ant has been dead for several days and the fungus has fed on the ant’s insides, its corpse becomes filled with fungal spores. A stalk emerges from the ant’s head, which allows the spores to be released into the air in search of another victim to infect.

So, could a parasite like Ophiocordyceps unilateralis ever evolve to infect humans? “The Last of Us” imagines a world in which it could: As a result of high temperatures due to climate change, a parasitic fungus takes over the human population. However, the transition from Ophiocordyceps unilateralis infecting ants to infecting humans would be nearly impossible. The conditions in which the fungus thrives and reproduces are far too specific — it even has difficulty infecting different species of ants. Furthermore, our body temperature is much too high for a fungus to survive. João Araújo, an expert on parasitic fungi at the New York Botanical Garden, explains that “if the fungus really wanted to infect mammals it would require millions of years of genetic changes.” 

Although this fungus would not be the cause of a zombie apocalypse, could it happen in another way? According to scientists, a zombie apocalypse is not impossible, but it is extremely unlikely. One instance of humans entering a zombie-like state is a result of “prions,” which are abnormal proteins that cause other proteins in the brain to share their misfolded shape. Prions are what cause the brain disease known as kuru, which is transmitted by eating human brains. This was seen in a cannibalistic tribe in New Guinea in the 1950s and ’60s. The disease causes an unsteady gait, changes in mood and personality and the inability to speak. However, this is the only example of a human disease akin to zombies that we have seen so far. Even then, it is far different from the typical zombie apocalypse scene that is portrayed in media. As far as an infectious disease that is transmitted by bite and causes violent zombies to rise from the dead, there is no need to worry about a zombie apocalypse happening anytime soon.