Whoever began to discover the universe of ‘The Last of Us’thanks to the new series of HBO Maxyou may have heard the word for the first time Cordyceps. In the video game and in the series, it is a fungus that grows inside the human body and causes a global pandemic, turning everyone it attacks into a zombie.
The truth is that the Cordyceps exists and can grow inside an organism… but it is practically impossible for it to do so inside a human being. At laSexta, we have spoken with Javier Diéguez-Uribeondo, a CSIC researcher at the Royal Botanical Garden and PhD in Mycology from the University of Uppsala, Sweden, with extensive experience in pathogenic fungi at the University of California, who answers all the questions that there may be around this fungus.
“He Cordyceps It is a fungus that is part of a group called the Ascomycetes, which are dispersed by spores. He Cordyceps includes entomopathogenic species, that is, they colonize insects. By colonizing them, they control their behavior and produce fruiting bodies (mushrooms) on their body”, defines the researcher.
With the clear definition, the question seems obvious: is there a real danger that, as told in the series, human beings become zombies because of the Cordyceps? “For this fungus, no“, clarifies Diéguez-Uribeondo, neither humans nor other mammals. Of course, the series assesses the possibility that a group of fungi can colonize us with the conditioning of climate change, and this is very possible.
“Let it be for a Cordyceps it would be very complicatedat least in the short term in evolutionary time (in millions of years), because it is the result of a selection process that it takes millions of years of coexistence between the pathogen and the human“he adds. What “can happen” and that “It’s been going on since 2011“is that there are species of fungi that, due to climate change, can affect mammals or humans, especially those with immunosuppression. “In 2007 a new species called candida auris which causes between 30% and 60% mortality in patients with immunosuppression”, adds the researcher.
The two “highly unlikely” conditions to be infected
That is to say, in the short term we can rule out this scenario that ‘The Last of Us’ draws us, although Diéguez-Uribeondo acknowledges how “scientifically well documented and set” the series is. “It unifies different processes that occur in different fungi, mainly in the Cordycepsin a situation that could affect us”, he affirms. However, for this to happen, “highly improbable” conditions must be given, which he explains.
“The first is the temperature. We control the fungal infection because we have a temperature of 37 degrees that we can regulate and increase with fever, when practically no fungus can live above 34 degrees“, he explains. The second point has to do with the fungus ability to adapt by releasing enzymes that would have to be released in a “chronological and specially ordered sequence” depending on the organism.
Fungal pandemics can occur”
To do this, the wall-degrading enzymes they produce should exactly match the composition of said wall: “For that to happen with us, the fungus would have to produce this series of degradative enzymes and this does not happen from one day to the next, but in a process of millions of years“.
Diéguez-Uribeondo mentions that there are various factors such as globalization, climate change or invasive species (vehicles of numerous emerging pathogens) that facilitate the explosion of these diseases caused by fungi. At the beginning of the second chapter, it talks about how a flour factory is the “perfect environment” so that the infection is ‘cultivated’, something that the researcher explains to us.
“The series wants to recreate how, when harvesting a field of cereals, you can collect many insects. Infected insect cuticles would incorporate spores of these fungi into the flours. The food industry has it very controlled and there are no pathogens for humans, what happens in the series is a recreation of the script to describe a source of contagion. The thing to keep in mind is that we are on a global stage; any pathogen from anywhere in the world can reach us at any time and from anywhereas has happened with COVID-19,” he says.
Why is he chosen? Cordyceps?
Of all the mushrooms that exist, it is striking why this one has been chosen Cordyceps as the baddest of all. Diéguez-Uribeondo talks about how he “controls” the insects in which he grows through some toxins with which “change their behavior“. In addition, it gives a sudden bite to these insects “like vampirism”, characteristics that fit in this world that ‘The Last of Us’ draws us.
“Fungal pandemics can occur and there are many pathogenic fungi to be afraid of”, he warns, but not like the Cordyceps of ‘The Last of Us’, a threat that, as presented in the series, is not likely to happen: “There are other alerts to pay attention to before“. Returning to those common factors of the fungi that we see in the series, the researcher mentions the mycorrhizae, which regulate soil water control and can communicate over “huge distances”. Possibly this sounds like more than one when remembering one of the final moments of the second episode of the series, with that connection in which, with a simple step, everything changes.
There is a change in the series with respect to the video game that he does see as “significant”, which is the change in the mode of contagion in humans, going from spores to a bite. He clarifies that the correct thing is what the video game includes, but he believes that forcing the actors to wear a mask could “tarnish” the final result in the HBO series. “They add to Cordyceps transmitted by bite when in reality it is by air“, he clarifies.
The real problems that fungi do cause
To get an idea of the problems that fungi are causing to the Earth’s flora and fauna, the researcher gives us examples such as the salmonid saprolegniosis that is leading to their extinction, the plague of the crab that has led to its near extinction in Europe and Asia, the coral bleaching caused by the Aspergillus wave fusarium in sea turtles that affects their spawns, as well as the sudden death oak either the dry of the oak which especially threatens Iberian holm oaks and cork oaks.
One of the few fungal diseases that affect mammals is called white nose disease, which is devastating bat populations in the United States. The fungus can be introduced through the nose when they hibernate thanks to the drop in temperature, colonizing and killing them, falling “like ripe fruit”.
“Society will now be able to realize, thanks to the series, that there are serious pandemics caused by fungi, animals and plants,” he comments. For example, the fungus Batrachochytrium dendrobatidis ha wiped out a third of the amphibian species on the planet in the last decades.
These are just some data to know the reality behind the series, of a threat that, although it may not affect humans in the short term, is changing our ecosystem. Only about 4,000 species of fungi They can affect humans of the almost five million fungal species, so you have to be cautious with the alert.