The Last of Us: Can Animals Get Infected?

While we do know that the entire world had fallen due to the effects of the Cordyceps Brain Infection (CBI) in The Last of Us, that’s because the CBI can take over the mind of a human being and force them to become mindless creatures that are aggressive and capable of passing the infection to other people. Of course, while we do know that the CBI affects humans, animals might be a different story. So, can animals get infected in The Last of Us?

Animals can still get infected by Cordyceps in The Last of Us, but it does not affect them in the same way as it does humans. That’s because animals can still carry the infection but aren’t as susceptible to the mind-controlling effects of the fungus as humans are. As such, most animals aren’t affected by the infection.

The question of whether or not animals can get infected by Cordyceps arose in episode 4 when there were clearly cattle that were obviously unaffected by the effects of the infection. In that regard, it becomes interesting to ask why the fungus can affect humans but not all animals. So, with that said, let’s look at whether or not animals can get infected in The Last of Us.

Can Cordyceps Infect Animals?

During the early part of The Last of Us, it was clear that something huge has affected humankind when people started attacking other people out of nowhere. This led to the fall of human civilization as 20 years passed by after the sudden change in the behavior of certain individuals. The aggressive nature of some humans was attributed to the Cordyceps Brain Infection, which infected humans and allowed fungi to take over the brain of the host to make the person a lot more aggressive so that the fungi could spread to other hosts through bites.

In the real world, Cordyceps is able to affect ants or insects as the fungus takes over the mind and body of the host and forces it to infect an entire colony. Meanwhile, in episode 2 of The Last of Us, we learned that the infection could now affect human beings after it evolved. And when the spores of the fungus spread through different products and when infected people started attacking others, that was when things started to go to hell.

Of course, human civilization fell because the infection could not be stopped or contained in the 20 years since it began. There was no cure for the CBI, as infected people needed to be killed. So, what about animals?

This question is interesting because of the fact that we saw Joel and Ellie driving past a field of buffalo in episode 4. The buffalos were clearly not as aggressive as infected humans, which implies that they were not infected. Meanwhile, in episode 2, Ellie was seen eating a chicken sandwich, which means that she ate chicken meat that wasn’t infected.

As such, this implies that animals aren’t capable of getting infected by the CBI. But that isn’t really the case. And we have to go back to the source material, which is the video game franchise, to understand whether or not the CBI can infect animals.

In the game, we saw Joel and Ellie encountering a giraffe that clearly wasn’t infected. However, at the University of Eastern Colorado, we saw that the duo encountered monkeys that were not infected as well but were used by the Fireflies for experiments for a cure to the CBI. 

While most of the monkeys were not affected by the infection, the thing is that some monkeys were not as lucky. In that regard, what is clear is that animals are likely to be more resistant to the effects of the CBI than humans. And because monkeys are closer to the genetic material of human beings than any other animals, it is understandable why some of them were affected by the CBI.

Meanwhile, animals that aren’t as close to human genetics as monkeys may be more likely to resist the effects of the CBI. That’s why the buffalo in episode 2 of HBO’s live-action version and the giraffe in the video game were not infected.

But what we are sure of is that, while animals aren’t as easily affected by the CBI as humans are, they are still capable of carrying the infection. In the game, one of the Fireflies shot himself after getting bit by a monkey that carried the fungus but was not affected by its mind-controlling effects. As such, we can make the conclusion that animals can still carry the infection but are not as likely to get infected as humans.

If animals can get infected, then we should have seen infected dogs and other animals running around biting people, similar to how shows and games with zombie viruses have infected animals attacking people. But that hasn’t been the case in The Last of Us.

Why Can’t Cordyceps Affect Animals?

The thing about The Last of Us is that it isn’t similar to shows and video games that have viral outbreaks, as the show and the game focus more on the story of Ellie and Joel instead of an overarching need to understand where the infection came from and how it can be prevented and cured.

That means that we understand little to nothing about the CBI due to how the story revolves more around the journey of the main characters. This also implies that we aren’t really sure why the infection does not affect animals like it does humans.

But there’s a good chance that animals aren’t as easily affected by the infection as humans due to the possibility that the fungus evolved only to the point that it can take over the minds of humans. Again, Cordyceps doesn’t normally affect humans in the real world but somehow evolved to be capable of infecting people in The Last of Us. As such, it is likely that the evolutionary track of Cordyceps only allowed it to infect humans, not animals. And considering that humans and animals are different in terms of their genetic makeup, it becomes understandable why certain diseases, viruses, and infections can affect humans but not animals.