Why a fungus makes a great causative agent for a zombie outbreak

 'Steve, are you okay? What is that thing growing out of your head?!' Steve was not okay; Steve was infected with a fungus called Cordyceps.

 'Steve, are you okay? What is that thing growing out of your head?!' Steve was not okay; Steve was infected with a fungus called Cordyceps.

Despite a lack of focus on the microbiology, I always enjoy a good zombie-themed book or movie.

Rather than let my knowledge of microbiology hamper my enjoyment, I simply appreciate the writer’s accuracy and dedication.

Taking a step back, science fiction thrives off fertile topics of real science to fuel stories of time travel, space travel and zombie apocalypses.

Is accuracy important in science fiction?

Science fiction is any idea that occurs in the head and doesn’t exist yet, but soon will, and will change everything for everybody, and nothing will ever be the same again. As soon as you have an idea that changes some small part of the world you are writing science fiction. It is always the art of the possible, never the impossible.
— Ray Bradbury, interview with the Paris Review in 2010

I agree with the late Ray Bradbury and feel there should be a possibility of truth in science fiction.

As scientists, is our enjoyment of science fiction hampered by our expertise?

When considering this topic, I immediately think back to a cartoon Helen shared with me.

Instead of simply enjoying the view on the beach, nerdy scientists cannot help be drawn to the details of hydrodynamics, aerodynamics, metrology and rates of evaporation of their beverage.

So, what happens when we watch movies or read fiction?

Although Neil deGrasse Tyson finds time travel science fiction to be far-fetched, he acknowledges it makes room for some interesting stories that dive into the human-psyche.

What is a ‘zombie apocalypse’ anyways?

In case you haven’t seen a movie or played a game dedicated to zombies, I will include a quick summary of the key plot elements while trying to withhold my disappointment in you, the reader, for not partaking in this great experience.

Fade in, the main character is introduced engaged in some facet of mundane, everyday life to soon be plunged into the chaos of a horrible outbreak of disease. This chaos pushes themes relating to the limits of human compassion being trampled by the selfish need to survive to take center stage leaving pathology and microbiology by the wayside.

Although I find it disappointing, the survivors are often not interested in details of the outbreak itself as they fight off hordes of cannibalistic, degenerate human beings.

Can’t really blame them.

But wait, there are exceptions!

More often than not, the disease is often attributed to some virus and left at that. Viruses definitely make for fertile science fiction given the infinity of viruses on our planet.

In fact, a great YouTube channel dedicated to scientific communication covered the plausibility of a viral-based zombie outbreak. Check out that video below! 

Although flashy, zombies make for a poor vector of disease.

In my opinion, most zombie stories are plagued – pun intended – with one serious flaw: the disease is transmitted via direct contact, achieved through an attack by a zombie. This requirement causes me to classify most zombie diseases as a non-contagious disease due to the special requirement of crazed cannibals to spread

(If you want to argue with me that zombies are still people… I recommend you watch The Walking Dead).

Although ‘successful’ non-contagious diseases exist with the Black Death and Lyme disease, these diseases can be prevented by controlling the vector, which in this case are zombies.

Maybe I am simply overconfident in my fellow New Englanders and their ability to build impressive gun stockpiles, but most I feel confident a zombie outbreak could be relatively well contained.

Enter Naughty Dog and the cunning use of fungi.

As part of series of posts dedicated to notable nods to microbiology in pop-culture, I will highlight a recent game produced by Naughty Dog studios that deserves acknowledgement for making me giddy with the microbiology present within their latest game, The Last of Us. 

Naughty Dog Studios' The Last of Us in all it's glory. Definitely worth checking as a serious... microbiologist.

Naughty Dog Studios' The Last of Us in all it's glory. Definitely worth checking as a serious... microbiologist.

The Last of Us departs from the gold viral standard by pinning the zombie outbreak on a fungus that infects the host and takes root in the brain. This invasion of the brain turns the infected into the classic, brain-hungry zombie we are so familiar with to selfish propagate their existence.

Wait, is a fungus even capable of taking over a human’s brain?

The scary truth is yes.

Although not observed in humans, a fungus that results in ‘zombie’ ants exists called cordyceps. To summarize, the fungus forces the ants to an area optimal for fungal growth and spore production, a form of asexual reproduction that produces resistant and often airborne infectious agents for the fungus to find new hosts.

But, luckily cordyceps only infect insects so we have nothing to worry about, right?

No.

Most 'emerging’ diseases originate from other animals referred to as zoonotic diseases (75% says the CDC) . An obvious example is avian or bird flu, hence the name. Other well-known diseases also have animal-origin. HIV or Human Immunodeficiency virus actually originated from primates. In fact, the most debilitating infectious diseases tend to be zoonotic due to host incompatibility, a topic I will come back to at a later date.  

Check out this video that actually breaks down the details and models the spread of this 'fictional' zombie fungus disease.

 

With the use of fungi and spores, the zombie disease overcomes the limitation of solely relying on direct physical contact to spread. Now, the disease is able to spread via zombies and spores produced from ‘dead’ zombies and suddenly represent a much more scary and realistic scenario.

Let me know if you have questions or comments below and be sure to subscribe to our blog as I dissect other notable nods to microbiology in pop-culture.

Stay hungry!