How Did The Last of Us Fungus Start, Explained

Based on the 2013 namesake video game developed by Naughty Dog, the HBO post-apocalyptic action-drama series ‘The Last of Us’ is set in a world where a significant portion of humanity has been infected with a certain fungal infection and civilization has been destroyed. In 2023, Joel Miller (Pedro Pascal), a military veteran who lost his only daughter at the start of the outbreak, encounters a girl named Ellie (Bella Ramsey), who is the key to finding the cure for the infection. Accompanied by his smuggling partner Tess (Anna Torv), Joel sets out to escort Ellie out of the quarantine zone and get her to the scientists working for the Fireflies, an anti-establishment organization fighting the tyrannical rule of Federal Disaster Response Agency or FEDRA. If you are wondering about how the fungus started and how civilization fell apart, this is what you need to know. SHOW AND GAME SPOILERS AHEAD.

The Beginnings of the Infection

Set in 1968, the prologue scene of ‘The Last of Us’ perfectly sets up the show’s premise by indicating how the infection will begin about 35 years later. Epidemiologists Dr. Neuman (John Hannah) and Dr. Schoenheiss (Christopher Heyerdahl) attend a talk show about a potential mass global pandemic. While Schoenheiss expresses his worries about viral infection, Neuman is more concerned about the fungi. He talks about a particular type of fungus that can take control of the bodies of other organisms.

When Schoenheiss refutes this by pointing out that while fungal infections of this kind are real, they don’t happen to humans. Neuman accepts this, adding that the fungi cannot survive if their host’s internal temperature exceeds 94 degrees Fahrenheit. However, he proposes the notion of a slightly warmer world, which will prompt the fungi to adapt to the environment of that warmer world.

Image Credit: Liane Hentscher/HBO

The zombifying fungi that Neuman mentions above actually exist in the real world. They are called Cordyceps, which is a genus of ascomycete fungi. There are 600 species of them, most of which infect insects and other arthropods, though a few are parasitic toward other fungi. Fortunately, as far as we know, none of the Cordyceps affect humans. The root cause of the infection in ‘The Last of Us’ video games is a mutated strain of Cordyceps. The show will likely bring Neuman’s theory about climate change into the equation by relating it to mutation.

There are certain differences between the original game and the show. In the game, the infection began to spread in 2013, while it started to happen in 2003 in the show. Similarly, the main narrative is set in 2033 in the game, whereas the show is primarily set in a dystopic version of 2023. Moreover, the infection begins in South America in the game, whereas the ground zero in the show seems to be Indonesia.

In the game, the Cordyceps begin to spread in the United States in September 2013. The transmission to humans happens through the crops. The Texas Herald, the newspaper that Joel and Sarah read, publishes a report on the early stages of the outbreak on the front page of the September 26, 2013, edition. “Admittance spikes at area hospitals! 300% increase due to mysterious infection,” the heading of the report reads before stating, “FDA expands the list of contaminated crops. Massive recalls anticipated.”

“The Food and Drug Administration’s investigation of crops potentially tainted with mold continues across the country,” the body of the report says. “Initial lists distributed to vendors nationwide warned against crops imported from South America, but now the scope has extended to include Central America and Mexico. Several companies have already voluntarily recalled their food products from the shelves.”

Image Credit: Liane Hentscher/HBO

Within a few months after the infection began in the game, 60% of the human population has either been killed or transformed into one of the infected. When the fungi kill a host, spores begin to come out of their bodies, and those things can infect people. As the spores are airborne, most people carry a gas mask to protect themselves from them. And then, there is Ellie. Because she is immune to the disease, she doesn’t need a mask. The infection can also spread when an infected bites a living, non-infected person.

There are four stages of this fungal infection. In the first stage of the Cordyceps Brain Infection or CBI, the infected lose their humanity as the fungi take control of their mind. This happens in the first two days after the infection. In stage two, which occurs in the course of two weeks, the fungal growth in the brain diminishes the sense of sight. If the host survives for a year, they enter the third stage, where facial scars appear, and the sight completely diminishes. An infected can potentially develop the ability of echolocation as an alternative to sight. In the rare fourth and final stage, taking place about a decade after the infection, hardened fungal plates began to grow out of the body of the infected.

Read More: Where is HBO’s The Last of Us Filmed?