Can the fungus in the HBO series The Last of Us turn humans into zombies one day? Here's what biologists say

The fungal pathogen that wipes out much of humanity in HBO's latest series The Last of Us is real, but can the cordyceps fungus actually turn humans into zombies one day?

"It's highly unlikely because these are organisms that have become really well adapted to infecting ants," Rebecca Shapiro, assistant professor at University of Guelph's department of molecular and cellular biology, told Craig Norris, host of CBC Kitchener-Waterloo's The Morning Edition. 

In the television series, the fungus infects the brain of humans and turns them into zombies. In real life, it can only infect ants and other insects in this manner.

Shapiro believes the series does a good job of realistically depicting the fungus and how it behaves, but it would actually take millions of years for it to find a way to adapt to humans and infect them the way it does in The Last of Us. 

Humans are too warm and too complex for this particular fungus to jump to infect humans, she said.

There are, however, many fungi that do infect humans, though they cause rarely fatal conditions such as yeast infections and athlete's foot, James Scott, professor in the Dalla Lana School of Public Health at the University of Toronto, told CBC's Metro Morning.

Fungi can also easily infect people who are immunocompromised or have underlying disease, like what happened in India in 2021 when more than 4,000 COVID-19 patients died from mucormycosis fungus infections.

"There's this increasing population of people who are living with vulnerabilities and underlying diseases or who are immunocompromised, and as that percentage of the population increases, we have more people who are susceptible to fungal disease," Shapiro said.

In Ontario, Scott said, there are two main types of fungi to be concerned about. One is called blastomyces, which can cause lung infection and often shows up as a skin lesion that can be fatal.

Scott said it's a common fungus on the north shores of Lake Superior and east side of Georgian Bay. In 2021, the fungus infected more than a dozen people in a small First Nations community in northern Ontario and killed two people.

The other one found in Ontario, Histoplasma capsulatum, is associated with the accumulation of bird and bat droppings.

"As the populations of those other animals are impacted by these kinds of diseases, it stands to have negative consequences for us. So not a direct threat to our lives as yet, but still a major concern in the big picture," Scott said.

Climate change and new pathogens

With climate change on people's minds, Shapiro said there is reason to suspect rising global temperatures can cause new fungal pathogens to emerge in our environment.

Fungi are found in the soil and trees, and are well adapted to environmental temperatures, she explained.

"As environmental temperatures rise, then they become more well adapted to those warmer temperatures, and that starts to more closely match the temperature of a human body," Shapiro said.

Scott also said human activity, such as chopping down rainforests and other activity that drives climate change, can also increase opportunities of interaction between humans and fungi.

Drug resistance to certain fungi is also a concern.

Candida auris, for example, is a concerning fungal pathogen that has recently emerged, both Scott and Shapiro point out. The U.S. Centers for Disease Control and Prevention says the fungus is multi-drug resistant, difficult to identify and can have outbreaks in health-care settings.

The weather is certainly shifting, as was seen in many parts of southern Ontario this past week, when there were warmer-than-average temperatures.

Environment Canada meteorologist Geoff Coulson said changes occur to flora and fauna as our climate changes.

"There's species of wildlife that are encroaching further north and having impacts on the wildlife that was already entrenched here before they arrived. Types of plant life as well," he said.

"These changes are definitely occurring. There are types of things that couldn't have survived a winter 20, 30, 40 years ago that now stay in our our climate year round."

As the weather changes, there could be more in the way of invasive species as well, he said.

Climate change and evolving health patterns all sound like ideal situations for a fungal pathogen outbreak, but Shapiro said this information, and the fictional series for that matter, shouldn't scare people.

A 'fresh take' on zombies 

Video gamer Alex Pinto Lobo of Kitchener, Ont., hasn't watched the HBO series yet, but the video game it is adapted from is one he plays often.The video game franchise was first released in 2013.

"It's a really great story with a lot of great characters," Pinto Lobo said.

He said The Last of Us video game was a "refreshing change" from typical war games, like Call of Duty, that were popular at the time.

"The story was a fresh take on zombies and making nature more scary than people realize."

He doesn't worry about the plausibility of a fungal zombie apocalypse, though. He has read the science and understands the chances of a cordyceps fungal takeover is unlikely.

"Having now been through the pandemic, I don't think we're capable of such quick destruction," Pinto Lobo said.

Shapiro said she is happy to see an increasing awareness of fungal pathogens thanks to the show, but also wants to remind people that fungi are an enormous kingdom with millions of species.

"There's a few of them that can cause disease in humans, but they also play these really amazing roles in our lives and do incredibly beneficial things that support human life," she said.