I was ten years old when I first found out about the zombie-ant fungus, Ophiocordyceps unilateralis. Back then I had made the only logical conclusion that an elementary schooler could make about a mind controlling infectious species, zombies were real and the ants were going to bring on the apocalypse. After my teacher had assured me that no, humans could not be infected by the fungal disease that the ants were susceptible to, I put it in the back of my mind.
[1] Photo Caption: A carpenter ant infected by the Ophiocordyceps unilateralis fungus
Flash forward to about a couple months ago when HBO’s new show, The Last of Us was released. Based off of the popular video game, the award winning show follows survivors in a post apocalyptic world where the very same zombie-ant fungus has mutated to be able to infect humans. I may or may not have binged it all in two separate sittings (no further comment).
So what is Ophiocordyceps unilateralis? It's a fungus, commonly known as Cordyceps, which once it infects an insect, takes control of their body and mind. According to Encyclopedia Britannica, the most common victim of the fungus is carpenter ants. In order to take control, the Cordyceps spore form attaches itself to an unsuspecting ant and uses its threadlike strands, also known as infective hyphae, to enter inside the ant. Once it’s infected the insect and takes control, the fungus makes the ant crawl up a bush or tree until it has reached optimal living conditions for the Cordyceps to take root. From there, it kills the ant and begins growing, often protruding a small stalk like in the image above, only to rain its spores down below to infect more. And, since the chosen location tends to be near the ant’s original colony, it can send down spores to infect the other ants once it’s grown enough. Crazy, right? Luckily, this fungus is limited to infecting insect life, at least for now. (You can read more about Cordyceps from the NYT here.)
The Last of Us isn’t the only type of media to use a similar organism in its storyline. Another popular zombie film and book, The Girl With All The Gifts, follows another fungal based apocalypse. This story follows a similar plot in that there is a child and adult who have to work together against the odds to save everybody from the apocalypse, learning to navigate a fungal infested world along the way. But why are we so interested in these types of zombie movies anyways? To get to the bottom of this, you have to understand what these ideas are based off of.
[2] Photo Caption: Opening credit scene for HBO’s The Last of Us featuring Cordyceps
One of the very first scenes of The Last of Us follows a scientist who is brought in to study the fungus. The focus here is how climate change has mutated the virus enough that it could survive inside humans, as well as insects. This wouldn’t be the first time that pathogens have evolved to transfer from other creatures to humans: just take COVID-19 as an example. Contracting infectious diseases by eating infected food happens fairly often as well, which is the source that is used in the show. The thing about fungal infections, however, is that they are spread via the environment, such as through an exposed wound or inhaling spores like the zombie-ants, rather than a nearby sneeze or cough. Additionally, it’s unlikely that any effects of fungal diseases on humans would be long term since they are typically only able to grow in temperatures below the human body’s (some scientists suggest that humans may have evolved to protect them from things just like this!). So, having a fungus like Cordyceps mutate to infect humans is pretty unlikely, unless it learns to adapt to warmer environments through climate change. As our climate warms, evidence shows that many other diseases are spreading faster or more effectively, such as those transmissible through mosquito bites who can now live in new areas and survive longer with rising temperatures. Additionally, there is risk for it to alter the way the fungus jumps from specimen to specimen, especially as the way that we interact with the environment changes with the climate.
The thing I find most interesting, however, is that we simply just don’t know for sure. As much as I would like to claim that we are safe from any future fungal based epidemics that would reduce the human population to a zombie state, there is a lot we still don’t know about pathogens like Cordyceps, especially as they are changing so rapidly with changes in our climate system. Just because there hasn’t been a fungal disease that travels from person to person recorded before doesn’t necessarily mean it doesn’t or will never exist. And, even if it’s not to the extent that is shown on shows like The Last of Us or The Girl With All The Gifts, some less deadly diseases have already been showing signs of similar adaptations, such as the yeast infections that the Yale Medical School speaks about here. All in all, we are at no immediate risk of becoming zombified by the same disease that carpenter ants are, but it’s worth thinking about how our changing world might be affected by the climate down the line.
This past month, I had the pleasure of taking care of the turtle ants (Cephalotes varians) we have here in the HMC Bee Lab. Watching these social insects interact with each other, especially so soon after seeing media coverage about zombie-ants, has definitely got me thinking about what our future will look like. And well, if the consequence of our actions do result in an ant-inspired apocalypse, maybe they can teach us a bit about how to survive a fungus infested world.
Media Credits:
[1] Photo by Alexander Wild: https://www.alexanderwild.com/Insects/InsectKilling-Fungi/i-PXRsBWT
[2] Photo from HBO’s The Last of Us opening credit scene: https://www.youtube.com/watch?v=8SWhBsbxmpk
[3] Photo by Ruby Peterman
Further Reading:
Backman, Isabella. “‘The Last of Us’ Apocalypse Is Not Realistic, but Rising Threat of Fungal Pathogens Is.” Yale School of Medicine, 6 Feb. 2023, medicine.yale.edu/news-article/the-last-of-us-apocalypse-is-not-realistic-but-rising-threat-of-fungal-pathogens-is/.
Elizabeth Weise and Karen Weintraub. January 17. “Where Did Covid-19 Come From?” National Emerging Infectious Diseases Laboratories Where Did COVID19 Come from Comments, www.bu.edu/neidl/2021/01/where-did-covid-19-come-from/. Accessed 17 May 2023.
Gadre, Aditi, et al. “The Effects of Climate Change on Fungal Diseases with Cutaneous Manifestations: A Report from the International Society of Dermatology Climate Change Committee.” The Journal of Climate Change and Health, vol. 6, 2022, p. 100156, https://doi.org/10.1016/j.joclim.2022.100156.
Lu, Jennifer. “How a Parasitic Fungus Turns Ants into ‘Zombies.’” Animals, 24 Jan. 2023, www.nationalgeographic.com/animals/article/cordyceps-zombie-fungus-takes-over-ants.
Nnadi, Nnaemeka Emmanuel, and Dee A. Carter. “Climate Change and the Emergence of Fungal Pathogens.” PLOS Pathogens, vol. 17, no. 4, 2021, https://doi.org/10.1371/journal.ppat.1009503.
Prillaman, McKenzie. “Climate Change Is Making Hundreds of Diseases Much Worse.” Nature News, 12 Aug. 2022, www.nature.com/articles/d41586-022-02167-z.
SHARMA, ARJUN V.K. “Opinion: This Rapidly Spreading Deadly Fungus Is a Warning about Climate Change.” Los Angeles Times, 12 Apr. 2023, www.latimes.com/opinion/story/2023-04-12/climate-change-fungus-outbreaks-candida-auris.
Yong, Ed. “How the Zombie Fungus Takes over Ants’ Bodies to Control Their Minds.” The Atlantic, 12 July 2021, www.theatlantic.com/science/archive/2017/11/how-the-zombie-fungus-takes-over-ants-bodies-to-control-their-minds/545864/.
Zimmer, Carl. “After This Fungus Turns Ants into Zombies, Their Bodies Explode.” The New York Times, 24 Oct. 2019, www.nytimes.com/2019/10/24/science/ant-zombies-fungus.html.
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