March 28, 2023

The Last of Us: Can Fungal Pandemic Create Zombies? – 29/01/2023 – Science

The new HBO series “The Last of US” presents a post-apocalyptic scenario in which thousands of people are turned into zombies after a fungal infection becomes a pandemic. The series was the second biggest premiere of the year on the HBO MAX platform, and the third episode is available this Sunday (29).

The scenario may be fictional, but the type of fungus represented in the series actually exists. They are fungi of the genus Cordyceps and Ophiocordyceps and in real life they turn their victims into zombies.

The spores of this type of fungus enter the victim’s body, where the fungus grows and begins to steal the host’s mind until it loses control and is forced to climb to higher ground. The parasitic fungus devours its victim from the inside, extracting every last nutrient as it prepares for its grand final act.

Then – in a scene more disturbing than the scariest horror movie – a death tentacle erupts from the head. This fungus body spreads spores around it – dooming other victims to the same fate if they are too close to become infected.

Fortunately for us, fungi of this genus are capable of infecting only ants – and only a few species. Other similar fungi infect other insect species in a similar way. This BBC documentary shows an ant infected with the fungus:

The function of these parasitic fungi inspired the video game The Last of US, on which the HBO series was based.

In the plot of these works of fiction, Cordyceps fungi become capable of infecting humans and causing a pandemic capable of leading to the collapse of society.

But in the real world, is a Cordyceps pandemic—or one caused by another fungus—something that could actually happen?

“I think we are dangerously underestimating fungal infections,” says Dr Neil Stone, a leading mycologist at the London Hospital for Tropical Diseases. “We’ve been doing this for too long and we’re completely unprepared to deal with a fungal pandemic.”

List of fungi dangerous to humans

At the end of October last year, the World Health Organization (WHO) published its first list of fungi with the highest risk to public health.

The fungi on the list are indeed menacing, but—to our relief—none on the list are capable of turning people into zombies.

Why not?

Microbiologist Charissa de Bekker at Utrecht University in the UK studies how Cordyceps fungi zombify ants, and says she doesn’t see how this could happen to humans.

“Our body temperature is simply too high for most fungi, including Cordyceps,” he explains. “Their nervous system is simpler than ours, so it’s much easier to steal an insect brain than the complex human brain.”

In addition, he explains, their immune systems are very different from ours, which would also make this “kidnapping” difficult.

Most parasitic Cordyceps species have evolved over thousands of years to specialize in infecting only one insect species. Most do not jump from one insect to another.

“For this fungus to be able to pass from an insect to us and be able to infect us in the same way, it’s a very long distance,” says Bekker.

death threats

However, the threat of a fungal pandemic is very real, although it has long been underestimated. “People think of fungi as something trivial, superficial or unimportant,” says Dr Neil Stone.

Only a few of the millions of species of fungi cause disease in humans. However, some of them can be much worse than an infected toenail or chile.

The fungus kills about 1.7 million people a year – about three times more than malaria.

The WHO has identified 19 different fungi that it considers to be of concern.

The most serious are Candida auris, Cryptococcus neoformans and Mucormycetes – which eats away at our flesh so quickly that it leads to severe facial injuries.

The global threat of candida auris

THE candida auris it’s yeast – and it gives off the same fermenting smell as a brewer’s or bread dough.

But unlike the beneficial yeasts we use for food, candida auris it is a terrible pest.

It infects the blood, nervous system and internal organs. The WHO estimates that half the people were infected by candida auris mold.

The first documented case was in the ear of a patient at Tokyo Geriatric Hospital in 2009, and since then the fungus has spread around the world.

THE candida auris it is very difficult to fight – some strains are resistant to all the antifungal drugs we have. For this reason, it is often called a “super fungus”.

Transmission is mainly through contaminated surfaces in hospitals – it’s a really difficult fungus to completely clear. Often, the solution is to close entire hospital wards, which has already happened in the UK.

Neil Stone says that the candida auris it is the most worrying type of fungus and we cannot ignore it, as a pandemic caused by it could lead to the collapse of health systems.

deadly fungus

Another deadly fungus – o Cryptococcus neoformans – is capable of entering the nervous system of humans and causing devastating meningitis.

Britons Sid and Ellie contracted the disease in the early days of their honeymoon in Costa Rica. Elle started feeling sick, and her initial symptoms – headaches and nausea – were attributed to too much sun. But then he started having very strong spasms and seizures.

“I’ve never seen anything worse, I felt so helpless,” Sid tells the BBC.

The tests done showed inflammation in his brain and identified Cryptococcus as the cause. Fortunately, Ellie responded to treatment and came out of the coma after 12 days on a ventilator.

“I just remember screaming,” she says, who was delusional when she was infected.

He is now recovering well.

Ellie says she “never” thought a fungus could do this to a person. “You don’t think you’re almost going to die on your honeymoon.”

black fungus

Another threat to public health is Mucormycetes, also known as black fungus. It causes a very serious disease called mucositis, which usually affects people with weakened immune systems.

It reproduces so fast that, if grown in a laboratory, it can cause the lid of a petri dish to burst.

“When you let a fruit go bad and the next day it turns to mush, it’s because there was a slime fungus in it,” says Dr Rebecca Gorton, a scientist at HSL, the health services laboratory in London.

He says the infection is rare in humans, but can be very serious when it occurs.

The fungus affects the face, eyes and brain and can be fatal or leave people severely disfigured. An infection spreads just as quickly in the body as it does on fruit or in the lab, Gorton says.

During the Covid-19 pandemic, there was an explosion of black fungus cases in India. More than 4,000 people died. It is believed that people’s weakened immune systems and high levels of diabetes in the country helped the fungus to multiply. About 30 cases of mucositis infection were recorded in Brazil in 2021.

Should we take fungi more seriously?

Fungi cause infections very different from those caused by bacteria or viruses. When a fungus makes us sick, it is almost always picked up from the environment rather than spread through coughing and sneezing.

We’re all exposed to fungi all the time, but they usually need a weakened immune system to thrive.

Stone says a fungal pandemic would likely be very different from the Covid pandemic — both in how it spreads and the type of people it infects.

He believes the threat exists because of “the amount of fungi in the environment” and because of “climate change, international travel, the increasing number of cases and the deep contempt we have for treatments.”

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