A zombie fungi outbreak similar to the TV drama, The Last Of Us, might be a possibility due to global warming, warns a new study.
Pathogenic fungi cause disease in humans and other organisms and are already responsible for deaths in immune-compromised people.
So far, healthy individuals have not had to worry about these fungi, as they don’t thrive in the heat of our bodies.
However, a recent study conducted by scientists at the Duke University School of Medicine, has warned this could change in the future due to the warming of our planet.
The study found that raised temperatures can cause pathogenic fungi present throughout the world – known as Cryptococcus deneoformans – to speed up its adaptive responses – which could lead to heat resistance and a greater potential for causing deadly diseases.
The authors of the study warned that pathogenic fungi should be taken more seriously in order to avoid a situation akin to that in the HBO hit show The Last of Us, in which a global pandemic caused by a mass fungal infection transforms humans into zombie-like creatures and collapses society.
The Duke Med team, led by postdoctoral researcher Dr Asiya Gusa focused on three changing elements active under heat stress in C. deneoformans.
Though the study focused on just three, Dr Gusa added there were easily another 25 or more of these transposable elements which have the potential to mobilise.
The researchers used ‘long-read’ DNA sequencing to observe chromosomal segments – or transposons – and analysed how they move using computers.
They found that the rate of mutations in transposons were five times higher in fungi raised at body temperature (37 degrees Celcius) compared with fungi grown at 30 degrees.
One transposable element, called T1, even showed a tendency to insert itself between coding genes, which could lead to changes in the way genes are controlled.
An element called Tcn12 often landed within the sequence of a gene, potentially disrupting the gene’s function and possibly leading to drug resistance.
The mobilisation of transposable elements also worryingly appeared to increase more in fungi living in mice, with all three transposable elements mobilising in the fungus genome within just ten days of infecting the mice.
The researchers added that they suspect the additional challenges of surviving in an animal with immune responses may cause the transposons to become even more active.
‘These mobile elements are likely to contribute to adaptation in the environment and during infection,’ said Dr Gusa.
‘This could happen even faster because heat stress speeds up the number of mutations occurring.’
On the potential consequences of global warming and fungal evolution leading to a Last of Us-style apocalypse, she added: ‘That’s exactly the sort of thing I’m talking about – minus the zombie part.
‘Fungal diseases are on the rise, largely because of an increase in the number of people who have weakened immune systems or underlying health conditions.
‘These are not infectious diseases in the communicable sense; we don’t transmit fungi to each other, but the spores are in the air.
‘We breathe in spores of fungi all the time and our immune systems are equipped to fight them.’
Experts hailed the new study as outlining how ‘unpredictable’ the evolution of fungi can be.
‘It shows how increasing global temperatures may affect fungal evolution in unpredictable directions,’ said Dr Arturo Casadevall, chair of molecular microbiology and immunology at Johns Hopkins University.
‘As the world warms, transposons in soil fungi like Cryptococcus neoformans could become more mobile and increase genomic changes in ways that could enhance virulence and drug resistance,’
‘It’s one more thing to worry about with global warming.’
The next phase of research will look at pathogens from human patients who have suffered from relapsing fungal infections.
Dr Gusa says fungi and fungal diseases could be evolving far more rapidly than we expect.
‘We know that these infections can persist and then come back with potential genetic changes,’ she said.
‘These kinds of stress-stimulated changes may contribute to the evolution of pathogenic traits in fungi both in the environment and during infection. They may be evolving faster than we expected.’
The Last of Us TV show, based on the video game franchise of the same name, has gripped viewers across the world ever since its launch.
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