Movies

Consider the fungus: Mycologists talk about the realities of ‘The Last of Us’

January 24, 2023

In a show about bloodthirsty zombies and a shattered post-apocalyptic world, particularly based on a video game perhaps best known for the constant, low-level stress it instilled in gamers, for whom to die so many time they were considering giving up the game altogether seems to be an almost universal experience— you wouldn’t think flashbacks to a rosier, pre-pandemic past would make up the scariest scenes.

But they did. In the first two episodes of HBO The last of us, it wasn’t the murderous grannies sprinting or the clicker jump scares that proved to be the most haunting. For many viewers, it’s more like the opening scene of each installment, which both exposes the threat posed by the most formidable of threats: mushrooms.

OK, OK, not mushrooms per se, but mushrooms in general. The series premiere featured epidemiologists on a fictional 1960s talk show about the dangers of the pandemic. One proclaims – with laughter, then with shudder when the audience understands what he is saying – that he fears neither viruses nor bacteria, but fungi, which alone could have the power to create “billions of puppets with a poisoned mind permanently fixed on a single unifier”. objective: to spread the infection to the last living human being by any means necessary.

“There is no treatment for this,” he continues. “No prevention, no cure. They do not exist. It is not even possible to manufacture them.

Sunday’s episode jumped to the early days of the pandemic that would soon turn most humans into vicious spore-dealers. Called to a government facility in Jakarta to consult over the corpse of one of the earliest infected victims, a University of Indonesia mycology professor (a moving cameo by Christine Hakim) slowly discerns the threat posed by the newcomer, hosted by humans. ophiocordyceps mushroom. She ominously advises the soldier who brought her in: “Bomb. Bomb the city.

Turns out those crashing jets and dark museum rooms have nothing on the mushroom spectrum. Look The last of us it is to radicalize against the humble kingdom of the eukaryotes, to hate their piles, to fear their wicked mycelia. If you deduce it from the responses of some viewers, many are unlikely to sample never again.

To cure my burgeoning mycophobia, I turned to Jonathan Cale, assistant professor at the University of Northern British Columbia, who studies fungus-tree interactions in forests, and Matthew Kasson, assistant professor of mycology at the West Virginia University, whose work has focused on Massospora. cicadina, a parasitic fungus that – swallowed – infects cicadas, alters their behavior to spread and ultimately seals their fate.

“It’s no exaggeration for me,” Kasson says of The last of us‘s harmful fungi. “They are stranger than fiction.”

The virgin mushroom against Chad 94 degrees

The opening scene of The last of us features the second epidemiologist attempting to allay the first’s concerns about a fungal pandemic by reminding his colleague that fungi cannot survive temperatures above 94 degrees, leaving us humans snug and snug from their spongy claws .

Alas: “It’s not true”, says Kasson. “There are a number of fungi that can persist. In fact, we know that the limit for fungal growth is about 62 degrees Celsius” – about 143 degrees Fahrenheit, and more than enough heat to cause a burn -” after which many or most eukaryotes, including mushrooms, cannot grow”.

“No prevention, no cure”

The last of us makes a big deal of the idea that since cordyceps is a fungus, it cannot be treated with drugs. It’s not true: antifungals abound to treat common fungal conditions like athlete’s foot, yeast infections, ringworm and dandruff.

But the show is fair that fungi are particularly difficult to combat, Kasson says. “Fungi are more closely related to animals than plants. But it’s really hard to get rid of dandruff because they’re eukaryotes and animals and fungi share a lot of similarities. It’s hard to fight them without us fighting us. So they need to come up with specialized types of compounds that can kill the fungi without harming the host.

Options remain few, even though doctors and scientists in The last of us probably wouldn’t have immediately given up on fighting cordyceps. Take it from microbiologist Arturo Casadevall, who told Hopkins Bloomberg Public Health magazine last year: “Because we don’t worry about fungi, little work is done with fungi. So we don’t have too many drugs. We don’t have fungal vaccines, and everything is getting a bit circular.

Another source of nightmare: Casadevall believes that we have already seen a mushroom, white ears, adapt to human body heat. “As the world gets warmer, mushrooms will have to adapt,” he said. “Every hot day is a selection event.”

Smooching the Wood-Wide Web

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Please come back! The two are, for better or worse, linked: the two play on a phenomenon known as “wood-scale webbing”, in which fungi allegedly allow disparate trees in the same forest to communicate. Like the catmen and the grains of light of Avatar unite under a single fibrous connection dubbed “Eywa”, so do the Infected and their fearsome vines. (Theirs might not involve a soul tree.)

In recent years, the theory has emerged as scientific fact in everything from the 2019 Pulitzer Prize winner The dominant story to Ted Lasso. More recently, a number of mycologists have spoken out against the concept, which they call exaggerated.

But mushrooms communicate, in a way. “There is ample evidence that the chemicals emitted by a fungus influence the growth and development of fungi of the same or different species. Many of these chemicals are volatile, diffuse through the air and alter the behavior other distinct fungi,” says Cale, who has studied the phenomenon.

In The last of us, Joel kills an infected person at the State House. As the newly (re-)dead Infected falls to the ground, tendrils spread across the corpse’s fingers, alerting dozens of nearby Infected to the group’s location. It’s unclear whether this is a defensive mechanism or a hunt for new victims, but there is real evidence of the former in some plants, Cale says.

“The types and amounts of volatile chemicals emitted by fungi change when a fungus is injured or fed by predators (eg, soil-dwelling insects),” he says. “These altered chemical profiles can reduce or even completely deter additional predation. Thus, protecting the fungus from further damage.

Cale cautions that it is not known if the response may affect other fungi, but it has been observed in plants. “Chemicals emitted by plants attacked by insects or pathogens stimulate the production of defense chemicals in distant unattacked plants.”

Cordyceps, carpenter ants and the zombies must chew

At The last of us, people are infected with cordyceps if they are bitten by someone who is already infected. (The game also features spore infection, though they don’t appear in the HBO edition yet.)

Call it creative freedom. The choice of cordyceps as the fungal enemy of the series is inspired by the real behavior of carpenter ants. A cordyceps infection will in effect turn an ant into a puppet of the fungus, prompting it to climb high, attach itself to a leaf or twig, and die. “Once the ant is dead, the fungus will burst violently, usually from the ant’s head,” Kasson explains. “And then spores will rain down from this fruiting body onto unsuspecting ant victims below.”

But what we see on The last of us is a totally different form of spread: active host transmission, which requires direct contact with a host to become infected. This, alas, has at least some basis in reality.

Kassen specializes in the zombie cicada fungus, in which cicadas infected with Massospora cicadina have the back of their bodies gradually killed by the fungus, which also produces a psychoactive compound “that makes them hypersexual and super, super focused.”

“They continue to mate and fly as if nothing has happened,” says Kasson. “So that way it spreads from cicada to cicada as a sexually transmitted disease.”

…Is a devastating fungus the greatest threat to humanity?

So should we, like the epidemiologist of The last of us‘s premiere, lying in bed at night fearing the day when a particularly nasty fungus adapts to thrive in humans?

Recent studies have documented an increase in certain fungal infections, believed to be the result of the COVID-19 pandemic. In particular, patients with COVID, receiving common treatments like steroids which can suppress the immune response, and those suffering from the lingering effects of long COVID may be immunocompromised, opening the door to fungus they might otherwise have repel.

“It’s not that there are super mushrooms emerging,” Kasson says. “These are common soil fungi, common sink and drain fungi, that just take advantage of a weakened immune system that can’t react against them.”

“So do I suspect we will see a higher incidence of fungus in a warming world? I think we can. But these will be some of the same fungi that we’ve been quietly battling in hospitals and clinics for a long time. It’s just that people are becoming more aware of them because more of the population may be immunocompromised due to things like COVID-19 and other viruses that can predispose us to subsequent invasion by these generally ubiquitous fungi.

In other words: fear the virus and the mushroom.