Can a fungus actually start a zombie apocalypse?

The video game adapted to a show, The Last of Us, features a fungus that can turn people into zombies. This fungus actually exists.

 Ant infected by Ophiocordyceps unilateralis fungus (photo credit: Wikimedia Commons)
Ant infected by Ophiocordyceps unilateralis fungus
(photo credit: Wikimedia Commons)

Ophiocordyceps unilateralis is a fungal pathogen that infects ants, hijacks their bodies and eventually kills them.

An infected ant will act erratically. The insect is forced by the fungus to leave its colony and nest in a forest canopy to make its way to a lower level where the temperature and humidity are more favorable for the fungal pathogen to thrive. The ant will then attach itself to the underside of a leaf using its mandibles. It will remain there until it is killed by the infection.

The Ophiocordyceps unilateralis fungus, from within the ant, produces mycelia, a root-like structure of fungal branches that help securely attach the host insect to the leaf. 

Once this has occurred, a stroma, or a solid, stick-like mycelia protrusion, growths through the back of the ant’s head. This allows for further dispersion of fungal spores. 

A 2012 study from the peer-reviewed Journal of Invertebrate Pathology, characterized this process of a fungal infection hijacking the body of the ant as “an adaptation that benefits the fungal pathogen by placing the host in sites conducive to widespread dispersal of the infective propagules.”

 A screenshot from The Last of Us video game (credit: FLICKR) A screenshot from The Last of Us video game (credit: FLICKR)

The idea of a lethal infection that seizes control of its host and forces it to spread the infection is directly reminiscent of the zombie genre which usually has the apocalypse beginning from the infection.

In fact, WNYC reported in 2013 that it is Ophiocordyceps unilateralis itself that inspired The Last of Us creative director Neil Druckmann to create a new way to annihilate mankind in his video game.

Could Ophiocordyceps unilateralis actually create human zombies?

The short answer is that it is incredibly unlikely. As it is, while there are various strains of this fungus, each one is only able to able to target a specific ant species. Being unable to make the leap from one ant species to another, it would need to undergo dramatic evolutionary development. 

“If the fungus really wanted to infect mammals it would require millions of years of genetic changes,” parasitic fungi expert João Araújo tells National Geographic.

Is climate change exacerbating fungal infection?

According to the national weather service, the average global temperature in 1900 was 12.1 degrees Celsius. In 2021, it was 13.5 degrees Celsius. As far as a few degrees can alter the weather, disrupt ecosystems, raise ocean surface levels, etc, this is a dramatic rise. Furthermore, the rate of rising temperatures is ever-increasing as climate change progresses.

Rising temperatures could spread fungal infections. As most of the human body is too warm to host the majority of fungal pathogens, as the difference between human body temperature of climate temperatures decreases, the easier it will be for fungi to evolve to be able to spread to human physiology

In fact, even beyond fungal infection, climate change can make people vulnerable to illnesses. For instance, the warmer it gets, the further mosquitoes that carry diseases such as malaria, dengue, and West Nile virus can spread. There are also examples of viruses that had been trapped in permafrost being exposed due to thawing.