The 'Last of Us' Show Goes Into More Detail About the Fungus-Based Virus Than the Games

With the entire world having incorporated quarantine culture and the pandemic lifestyle into their daily routines, a show about a highly contagious zombie-like disease would probably leave most of us on edge. The Last of Us on HBO works to play on that lingering virus-related anxiety that most of us have developed.

Based on the critically acclaimed video game, the series focuses on Joel Miller (Pedro Pascal) and teenager Ellie (Bella Ramsey) as they attempt to survive in a post-apocalyptic United States that has been decimated by an infectious virus that turns people into mindless monsters.

The virus in question behaves much like fungus, in that mold and mushroom-like growths develop all over an infected individual. What exactly is this fungus in The Last of Us? Let's break down what we know about it.

While the Last of Us games only briefly touch upon the nature and origin of the fungal virus, the show explains it in much more explicit detail.

Season 1, Episode 2 — appropriately titled "Infected" — opens in 2003, shortly before the initial outbreak of the virus in the United States. In Jakarta, Indonesia, mycology professor Ibu Ratna (Christine Hakim) is approached by local authorities to examine the corpse of a flour factory worker who attacked her co-workers before getting killed.

She discovers a human bite mark on the victim's leg and fungal growths emerging from her mouth. Dr. Ratna later confirms that this strain of fungus is known as Cordyceps, a parasitic fungus that typically targets insects as hosts. She is also informed that some of the co-workers who were attacked have gone missing in the city. Fearing the Cordyceps' inevitable spread among human populations, she tragically urges the Indonesian military to bomb the city and destroy everyone in it to stop the virus.

Twenty years later, the spread of the Cordyceps has ravaged the United States, with society having largely fallen into disarray in the wake of the disease.

In the show, the Cordyceps behave much like a zombie virus. An infected individual loses higher brain function and becomes hyper-aggressive, and anyone who is bitten by them also becomes infected. Over time, the Cordyceps infection will spread across the body and will appear as fungal growths.

As scary as it may be to think about, Cordyceps actually exist in real life and behave in a manner similar to the show. According to real-life mycology professor Mark Ramsdale via Sky News, there are over 600 species of Cordyceps, some of which can use insects as hosts and take over their brains to control their motor functions to an extent.

As of this writing, there are no known records of Cordyceps infecting humans in this manner. In fact, people have even used Cordyceps in cooking.

The game —and subsequent series — deals with a form of Cordyceps that has undergone an aggressive mutation to be able to spread among humans. Still, the fact that this disease draws so heavily from nature is enough to make our skin crawl.

New episodes of The Last of Us premiere every Sunday at 9 p.m EST on HBO.