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Even in the world of video games and television, a zombie plague carried by a deadly fungus sounds almost too far-fetched.
But as HBO finally confirms the release date of The Last of Us season two, scientists say the show’s terrifying premise could soon be a reality.
Although there are no mushrooms capable of turning you into a zombie, experts are increasingly concerned that fungi could trigger the next pandemic.
And scientists say that the disasters like the California wildfires could be to blame.
As the climate around us grows warmer, fungi are rapidly adapting to hotter temperatures, which could allow them to thrive in our blood, lungs, and brains.
Already, scientists have discovered deadly fungi that are capable of spreading from person to person just like in The Last of Us.
And as extreme weather makes wildfires more likely, scientists say that deadly spores could be spread across the country in clouds of smoke.
Dr Martin Hoenigl, an expert on fungal pathogens from the Medical University of Graz, told MailOnline: ‘Generally speaking, there is definitely a possibility that fungi may cause a pandemic.’
As HBO reveals the release date of The Last of Us season two, scientists say that the fungal plague featured in the show could become a reality. Pictured, a human infected by a zombie fungus in the show
How could wildfires make The Last of Us a reality?
As climate change makes the planet less habitable for humans, it only becomes a better place for fungi.
In recent years, experts have become increasingly alarmed by the rapid spread of fungal infections outside of their normal ranges.
However, natural disasters like the LA wildfires could lead to fungal infections spreading even further.
Dr Hoenigl says: ‘Humans have adapted to the increasing number of disasters, so the number of human fatalities has remained stable over the last few decades despite higher frequency of natural disasters.
‘However, these disasters can, in the short and in the long-term facilitate fungal diseases by spreading fungal pathogens with wind or wildfire smoke.’
In the past, the way that fungal infections spread has meant infections have remained relatively rare.
Fungi typically get into your body through a mucus membrane, for instance by inhaling mould spores, or through a break in the skin, like a bite from a zombie in The Last of Us.
Wildfires like those which burned through LA this week spread fungal spores even further by sweeping them up in clouds of smoke. As climate change makes these events more likely fungal infections could become more of a problem
Last year, wildfires in Canada carried smoke down the East Coast, enveloping New York in a hazy smog. Fungal spores can hitch a ride on these smoke clouds to travel vast distances and make their way into people’s lungs
Since there aren’t any real fungal zombies out there, this means that fungi spread through the environment rather than from person to person.
But when wildfires send vast plumes of smoke into the air, these whip up fungal spores and carry them over populated areas.
Those spores are then inhaled by anyone caught in the cloud where they settle in the lungs and cause infections.
Between 2014 and 2018, California hospitals found that admissions for valley fever increased 20 per cent following a wildfire because of spores carried in the smoke.
In this way, fungal infections can travel vast distances that wouldn’t otherwise be possible, reaching distant populations.
For example, last year smoke from Canadian wildfires caused hazy smogs to form as far down the East Coast as New York.
If that smoke was carrying the spores of a fungal disease, New York could have found itself facing a sudden outbreak.
Why are fungal infections getting worse?
Last year was officially the hottest on record. As the planet warms, fungi are rapidly adapting to their new environment and becoming more deadly in the process. Pictured: Yearly average temperatures difference from the pre-industrial average during 2024
Infections caused by fungal pathogens like ringworm and athlete’s foot are not a new phenomenon.
But, until very recently, these numbers have been vanishingly small compared to the infections caused by bacteria and viruses.
Of the millions of fungi known to science, scientists estimate that there are only about 300 capable of infecting humans.
However, all around the world, the number of infections from dangerous and often entirely new fungi is rising at an alarming rate.
In California, diagnoses of ‘Valley fever’ which is caused by the fungus coccidioidomycosis, rose by 800 per cent between 2000 and 2018.
Meanwhile, in India, thousands of people contracted ‘black fungus’, scientifically known as mucormycosis, a disease which consumes the airways and faces of the infected.
Scientists believe that climate change has been one of the most important causes behind this acceleration, although it is not the only factor.
Our main defence against fungal infections is the fact that the insides of our bodies are too warm for them to survive.
In the video game adaptation, the world is destroyed by a fungal infection which turns people into zombies. This might seem far-fetched, but fungal infections are now on the rise around the world. Pictured, Bella Ramsey in The Last of Us
In America, the Valley Fever fungus has spread widely as the climate has warmed. Between 2000 and 2018, diagnoses of the infection rose by 800 per cent
However, one of the things that makes fungi unique is their incredible capacity to adapt.
That means that while fungi generally prefer to live where it is cool, the warmer the planet gets the better they become at surviving the heat.
Dr Hoenigl says: ‘By adapting to increasing temperatures in the environment, this brings them closer to being able to survive also at the human body temperature, and thereby becoming a threat to us humans.’
As the shifting climate alters global weather patterns, this can also expand existing fungal pathogens’ natural ranges.
One study, published in 2019, found that alternating patterns of drought and flooding could more than double the range of Valley Fever in the US by 2100.
The researchers estimate that the disease could be established in 17 states by the end of the century, leading to a further 50 per cent increase in cases.
This threat is made even more potent by the features of fungi’s unique survival powers.
‘Heat stress in the environment does not come alone. It comes together with other stress factors, like UV light exposure, [and] lack of nutrients for fungi,’ says Dr Hoenigl.
Experts say that climate change will produce patterns of drought followed by heavy rainfall which are perfect for the valley fever fungus, allowing it to spread across 17 states. Pictured: the current range of the disease
‘Fungi learn to adapt to all these stress factors, and by doing that they unfortunately also learn to cause more harm to us humans when they infect us.’
For example, fungal melanin, a pigment produced in response to heat, also offers fungi protection against acids, heavy metals, UV radiation, and radioactive waste.
To make matters worse, higher temperatures increase the rate at which fungi pick up mutations, making it more likely that they will develop resistance to anti-fungal treatments.
That means climate change is creating more fungi capable of entering our bodies and making those fungi even more deadly and harder to treat.
Why are fungal infections such a problem?
While the rapid spread of any pathogen would be alarming, fungal pathogens are even more troubling.
Dr Rebecca Drummond, a fungal immunologist from the University of Birmingham, told MailOnline: ‘Some fungi are particularly good at hiding from the immune system, so the immune cells don’t see it until it’s too late.
‘If you’ve got a nice healthy immune system typically these fungi are quickly cleared out, but when the immune system is broken in some way that’s when the infection can take hold.’
Just like in The Last of Us, when a fungus enters our body it spreads through our tissue and organs. In reality, these clumps of fungus cause severe damage which can be fatal
Once the fungus is inside us, it can spread through any part of the body including the blood, lungs, kidneys, and even our brains.
Some fungi will secrete toxins which damage the tissues around them, but others cause damage simply by forcing their way through the flesh.
Just like the infected in The Last of Us, real fungal infections fill the body with filaments called mycelium which cause physical damage to the body.
‘Particularly in the lung, you can get these big balls of fungi forming, they cause a lot of bleeding and eventually, the lung stops working,’ says Dr Drummond.
‘We see the same thing in the brain with meningitis with what we call a cryptocoma. It’s almost like a tumour but filled with fungal cells that cause a lot of damage.’
While these details might be disgusting, what really makes fungal infections dangerous is how hard they are to get rid of.
Unlike bacteria and viruses which are very different from humans, fungi’s closest relatives are animals like us.
Since their biochemistry is so similar to our own, it’s very difficult to design a drug that can damage fungi without also damaging our own cells.
Fungi like the one which causes valley fever (pictured) are developing resistances to our anti-fungal treatments. Since fungal infections are already hard to treat, so this means infections are likely to become more dangerous in the future
The handful of antifungal treatments that we do have are also widely used in agriculture to protect crops from devastating fungal outbreaks.
However, that creates far more opportunities for a strain of fungus to develop immunity.
Once it does develop immunity, it doesn’t take much for that resistant strain to start infecting humans.
Dr Drummond says: ‘That’s quite a scary problem because, if you’ve got a patient that has an infection that’s already highly resistant to the drugs you have, you don’t have many things on the shelf you can actually reach for.’
Could a fungal infection turn you into a zombie?
In The Last of Us, the fungal infection doesn’t just make people sick, it turns them into a zombie hellbent on spreading the infection further.
This idea is inspired by the cordyceps fungus which infects foraging ants in tropical rainforests.
This fungus spreads through the ant’s body, plugging itself into the brain of its host and taking control.
The cordyceps mushroom was the inspiration behind the zombie fungus in The Last of Us. This fungus infects the brains of ants and takes control of their nervous system, forcing them to climb to a vantage point from which the mushroom can spread its spores
The ant is then compelled to leave its nest in search of a humid climate more suited to the fungus’ needs.
Once there, the ant climbs to a vantage point, clamps its jaws to a leaf and waits for the mushroom to burst through its body and spread its spores onto any waiting ants below.
Fungi’s mind-control powers aren’t only limited to insects.
In 2022, researchers found that wolves in Yellowstone National Park infected with a fungus called Toxoplasma gondii were more likely to either leave their pack or become its leader.
However, Dr Drummond doesn’t think it’s likely that any fungi will be able to take over the human body like we see in the show.
She says: ‘Fungi can change your brain chemistry, we see this in drugs like magic mushrooms, but that’s quite different to the infections we see with pathogenic fungi.
‘Things like cordyceps are so well adapted to their insect hosts, it’s unlikely that we’ll see a big shift like in The Last of Us.’
How bad could things become?
Experts say that current fungi aren’t likely to create zombies or cause a pandemic like in The Last of Us games (pictured). However, some emerging fungal pathogens are now developing the ability to spread from person to person
Currently, Dr Drummond says that existing fungi ‘probably’ won’t lead to a pandemic.
Dr Drummond says: ‘They don’t tend to be infectious in the sense that you would catch them from another person, that means it’s much easier to contain fungal infections.’
However, thanks to the way climate change is changing fungi, the global picture could soon look very different.
In 2009, Japanese doctors discovered a new species of fungi in a woman who was undergoing treatment for an ear infection.
Named candida auris, it was hypothesised to be the first fungi to have emerged due to the pressures of climate change.
While the disease had probably lived in the wild before, rising temperatures meant that it could suddenly make the jump into humans.
Two years later, it had appeared independently in Venezuela, South Africa, and in India.
By 2019, candida auris was so widespread that the WHO classified it as an ‘urgent threat to public health’.
Candida auris was discovered in 2009 in Japan, but has since spread to dozens of countries including the US. This is made more dangerous by the fact that the disease can spread from person to person and is resistant to several antifungal treatments
What makes this so worrying is that candida auris can spread from person to person by sitting on surfaces.
This is especially dangerous in hospitals where the fungus can cause outbreaks by attaching itself to members of staff.
Additionally, candida auris is already strongly resistant to three of the most common antifungal treatments and several disinfectants, making it especially difficult to remove.
The good news is that candida auris isn’t dangerous to people with healthy immune systems, although this might not help us much in the long run.
Dr Hoenigl says: ‘There are multiple factors that have contributed to the steep increase of fungal infections in humans over the last decades; these include advances in medicine.
‘As the population survives longer, the number with serious underlying diseases who are considered immunocompromised is increasing.’
Better medicine has meant a long-term illness like HIV is no longer a death sentence but, at the same time, it has produced a growing population uniquely vulnerable to a fungal infection.
Between 2013 and 2024, the number of people who are immunocompromised, meaning they live with weakened immune systems, more than doubled.
The World Health Organization raised concerns over 19 ‘priority pathogens’ that are growing and becoming resistant to treatments, including yeasts and moulds. Four types of fungi were included in the critical priority group: aspergillus fumigatus, candida albicans, cryptococcus neoformans, and candida Auris
In the US, estimates now suggest that 6.6 per cent of all adults are immunocompromised.
Additionally, researchers are now showing that viral infections like the flu and Covid-19 have long-term effects on the immune system that leave people immunocompromised.
That means a once relatively safe pathogen like candida auris could become significantly more dangerous.
Ultimately, even if candida auris doesn’t become an issue, it might not be long before some fungus does.
Dr Hoenigl says: ‘We are now facing new and emerging fungal pathogens at alarming rates, both in humans but also in agriculture, where fungal pathogens are the prime disease threat to our crops and nutrition supply.’
And, as the temperature rises, more and more fungi will be making the jump from the environment into our bodies.
Dr Hoenigl adds: ‘Fungi are very sophisticated and masters in adaptation. In fact, they have existed in the world long before us mammals and will, with all likelihood, also exist after us.
‘By learning to adapt to new conditions, like a warming climate, they develop abilities that increase their virulence and make it easier for them to escape our immune system.
‘Currently, all signs indicate that fungal infections will continue to increase and become a bigger threat over the decades that come.’
WHAT ARE THE OLDEST FUNGI EVER DISCOVERED?
For many years, fungi were grouped with, or mistaken for plants.
Not until 1969 were they officially granted their own ‘kingdom’, alongside animals and plants, though their distinct characteristics had been recognised long before that.
Yeast, mildew and molds are all fungi, as are many forms of large, mushroom-looking organisms that grow in moist forest environments and absorb nutrients from dead or living organic matter.
Unlike plants, fungi do not photosynthesise, and their cell walls are devoid of cellulose.
Geologists studying lava samples taken from a drill site in South Africa discovered fossilised gas bubbles, which contained what could be the first fossil traces (pictured) of the branch of life to which humans belong ever unearthed
Geologists studying lava samples taken from a drill site in South Africa discovered fossilised gas bubbles 800 metres (2,600 feet) underground.
In April 2017, they revealed that they are believed to contain the oldest fungi ever found.
Researchers were examining samples taken from drill-holes of rocks buried deep underground, when they found the 2.4 billion-year-old microscopic creatures.
They are believed to be the oldest fungi ever found by around 1.2 billion years.
Earth itself is about 4.6 billion years old.
Earth itself is about 4.6 billion years old and the previous earliest examples of eukaryotes – the ‘superkingdom’ of life that includes plants, animals and fungi, but not bacteria – dates to 1.9 billion years ago. The fossils have slender filaments bundled together like brooms (pictured)
They could be the earliest evidence of eukaryotes – the ‘superkingdom’ of life that includes plants, animals and fungi, but not bacteria.
The previous earliest examples of eukaryotes – the ‘superkingdom’ of life that includes plants, animals and fungi, but not bacteria – dates to 1.9 billion years ago. That makes this sample 500 million years older.
It was believed that fungi first emerged on land, but the newly-found organisms lived and thrived under an ancient ocean seabed.
And the dating of the find suggests that not only did these fungus-like creatures live in a dark and cavernous world devoid of light, but they also lacked oxygen.
