Zombies, those horrific formerly human monsters, infected with parasites that control their brains. A fungal pandemic that hits humanity hard and endangers its future in an apocalyptic atmosphere. These scenarios belong to the world of science fiction and, hopefully, will never become reality… Right?
HBO’s new series The Last of Us takes place in the context of a epidemicepidemic of zombification, just like in the video game on which it is based. The disaster is caused by fungi of the genus Cordyceps, which control their host in order to find new victims to infect. Such a pandemicpandemic triggered by a fungus could it take place? For the moment this threat is not envisaged, but certain elements can encourage humanity to be kept on its guard.
Zombie-Making Mushrooms
You may be familiar with ant “zombifier” fungi, species of the genus Ophiocordyceps which develop in tropical foreststropical forests. They permeate ants with their spores, the reproductive cells that allow them to disperse, carried by currents ofairair. Once infected, the insects descend from the canopycanopy towards the ground, more conducive to fungal development, and attach themselves firmly under a leaf with the help of their mandiblesmandibles. After four to ten days, the reproductive system of the fungus, or sporophore, emerges from the lifeless body of the ants and can thus complete its reproductive cycle by disseminating its spores, and thus infecting new victims. It’s this biological interaction that is chilling in the FromFrom which inspired the designers of The Last of Us to create the central threat of the video game released in 2013.
Fortunately for us, Ophiocordyceps cannot survive our body temperature, however other fungi can affect the human nervous system. These can develop substances found in known psychotropic products, such as psilocybinepsilocybine of certain hallucinogenic mushrooms,acidacid lysergic contained in the ergot from which LSD is derived, or even the ethanol produced by yeasts, these unicellular fungi which are used in the development of alcoholic beverages. Others cause diseases that affect the nervous system such as meningitismeningitis which can be caused by Cryptococcus, but no fungus alters human behavior to better disperse. In fact, most of fungal diseasesfungal diseases do not pass from human to human, but their pathogenspathogens come from the environment and infect us through touch orinhalationinhalation of spores.
Emerging health issues
In the game The Last of Usscientists unable to find a cure or a vaccinevaccine suggest bombing the area where the infection occurs to get rid of it. If this is not a necessary scenario in our reality, it is true that there is no vaccine and few treatments for serious fungal infections, which are not always curable. These mostly affect individuals in the immune systemimmune system weakened following a first often viral infection, like people with AIDS. Most of the time, our immune system is able to eliminate pathogenic spores. The problem with treating these infections comes from the similarity of fungal cells to our own, which means that many of the effective solutions against fungi are also dangerous for us.
With the global warmingglobal warming, a new risk emerges. Fungi that manage to adapt to it could swell the ranks of pathogens for humans. A study published in Proceedings of the National Academy of Sciences reports that a species of Cryptococcus, which wreaks havoc in immunocompromised people, sees its adaptive responses increase tenfold with rising temperatures. By changing the regulation of its GenoaGenoa and their use, the fungus is likely to be more resistant to the heatheat and thus affect healthy people. Scientists fear that these potential new, more robust and difficult to treat pathogens could cause significant health problems in the future.
