A mycologist has revealed that the fungal infection, cordyceps, featured in HBO’s The Last of Us series is only three steps away from becoming a reality.

The fungus, which turns humans into crazed zombies in the show, already exists in the natural world.

Fungal Infection Group research associate Norman van Rhijn explained that in order for the fungus to infect humans, our immune system would have to change, body temperature would need to be overcome, and the structure of our body would have to be adjusted.

Van Rhijn noted that “we don’t fully understand it yet,” but that for a fungal pandemic to occur, “our immune system must become insufficient to clear the fungus before it invades our tissue.”

While the hurdles may seem massive, the mycologist believes they are not impossible to overcome.

The plot of The Last of Us is not as far-fetched as it may seem, as the show has taken inspiration from scientific evidence and simply sensationalized it a bit.

Van Rhijn said that he remembers the first scene where the scientists talk about the range of fungi and that “it’s all going to change,” adding that he would say that is almost 100 percent correct.

However, he also noted that such a drastic change is unlikely to happen in our lifetime.

The cordyceps fungus currently invades cold-blooded species like ants, so body temperature would be something the fungus would need to overcome to attack humans.

“Our elevated temperature is a thermal barrier for many things (including fungi) that can’t grow at that temperature,” Van Rhijn said.

Mycologist reveals fungus is only three steps away from making The Last of Us a reality

He explained that our temperature is part of our immune system, and that one reason we get a fever is to raise our temperature to fend off infections. In order for a fungus to infect humans, it needs to learn how to cope with a nearly 20-degree difference.

Van Rhijn noted that “our immunity as a whole” would have to change in order for the entire population to be infected by the zombie fungus. “It either needs to be a complete breakdown of our immunity to that fungus or the fungus needs to evolve a radical strategy not to be recognized by a complete range of cell types,” he said. “But in order for a fungal pandemic to occur, our immune system must become insufficient to clear the fungus before it invades our tissue.”

While the prospect of a real-life zombie fungus may be unsettling, it’s important to remember that van Rhijn believes such a drastic change is unlikely to happen in our lifetime. However, he also added that we should never say never.