The Last of Us: Fungal Infections Really Can Kill – and They’re Getting More Dangerous

Fungal Infections
But even if a fungus is able to adapt and grow at warmer temperatures, it’s still unlikely it will spread through a population the same way a virus might.

Most fungal infections aren’t like other infectious diseases, in that someone infected with one usually can’t give it to someone else. That’s because most fungal infections tend to only infect people with specific risk factors – such as people with weak immune systems.

Fungal infections tend also not to spread between people because of the way infections start. Many serious fungal infections begin in the lungs, after inhaling fungal spores in the air. Although we each inhale hundreds of fungal spores daily, we almost never get sick because our immune system is highly efficient at destroying spores.

If the immune system fails and spores germinate in the lung, they can form different types of fungal cells that cause infection. But there’s little evidence to suggest fungi will also produce airborne spores once inside our lungs – meaning that while we can inhale fungal spores, we can’t exhale them.

Serious fungal infections can spread from the lungs into other organs – including the brain. Fungal brain infections are among the most lethal fungal infections. Most of these are caused by a fungus called Cryptococcus neoformans, which causes cryptococcal meningitis.

Around 100,000 people die from this disease every year. No other fungal infection causes more deaths in humans.

Cryptococcal meningitis happens when a person with a defective immune system – usually caused by Aids – inhales the fungal spores. The fungus escapes the lungs and gets into the brain – although exactly how this happens isn’t well understood. Once in the brain, infected patients experience symptoms such as severe headache, fever, vision problems and seizures.

While the infection is treatable with anti-fungal drugs, these are expensive – meaning those who need them can’t afford them. The Cryptococcus fungus can also become resistant to these anti-fungals.

But while there are certainly fungal infections which can spread to the brain, we probably don’t have to worry about the zombie Cordyceps fungi adapting to infect us as it does in The Last of Us – well, at least not anytime soon.

Cordyceps is not adapted to grow at our internal body temperature, nor is it able to contend with our immune system (which is far more advanced than that of an insect’s) to infect both our brain and nervous system at the same time. It would take many thousands of years of evolution for it to overcome this.

Although fungal infections are unlikely to cause a worldwide pandemic or zombie apocalypse, there’s still reason to be concerned. The number of people becoming ill with a serious fungal infections has been steadily rising over the last half century. This is concerning as we’re much less able to treat fungal infections compared to other types of infections because we have fewer antifungals.

Developing these drugs is also tricky, as fungi share similar biochemistry to our own bodies. The rise of drug-resistant fungi also puts us at threat. It’s clear more attention needs to be given to the potential dangers of fungi before it’s too late.

Rebecca A. Drummond is Associate Professor, Immunology and Immunotherapy, University of Birmingham. This article is published courtesy of The Conversation.