The Last of Us - Mycology in the limelight

20 April 2023

If you’ve binged the first season of the hit TV show The Last of Us or overheard people discussing it in the lunchroom, you have probably heard the question that has taken social media by storm – Could a fungal pandemic take over the planet, wiping out all humans?

The Last of Us, based on a 2013 video game, is a new post-apocalyptic drama that features Cordyceps, a fungus known for infecting insects. Cordyceps begins infecting humans for the first time, taking over their bodies and brain to cause unusual ‘zombie-like’ behaviour.

We asked Dr Sarah Kidd, Head of the National Mycology Reference Centre within SA Pathology, that same question. Of course, her answer was not as straight forward as we had hoped, but it gave us insight into the fascinating world of Mycology and how the Last of Us has given it a long-awaited spotlight.

“For the first time, people are interested in fungi. They now understand that there's more to it than superficial infections like athlete's foot. With the COVID-19 pandemic having just happened, and then watching this show, it has people asking, could this happen with fungi as well?”

“In the sense of what’s happening in the show, it’s unrealistic, but we are already experiencing a slow-moving fungal pandemic of sorts” says Sarah.

Move over Cordyceps

If the disease featured in the story doesn’t pose a threat to humans, what fungi does? Sarah explains that there are several fungal diseases that are becoming prominent and, in some circumstances, harder to diagnose and treat.

“Candida auris is a new yeast-like fungus that emerged in 2009, and was overlooked for nearly five years, until suddenly in South Africa, India and the USA, patients started to present with difficult to identify Candida infections that were not responding to treatment” Sarah explains.

It was soon realised that this was a new species that couldn’t be identified using the current technologies in labs, and that it was multi-drug resistant. But a lot of work has been done very quickly to better understand this species, and rapid diagnostic tests have been developed and the databases used in our lab identification methods have been adapted so that it can be more easily diagnosed and identified.

“Unfortunately, Candida auris is still causing mayhem globally. And since Australian borders have reopened from the COVID-19 pandemic, we're starting to see more and more cases here in people who've spent time in hospitals overseas. Luckily, we have developed a PCR assay for rapid screening, which has made diagnosis faster, our labs safer, and allows the hospitals to isolate affected patients to prevent spreading” says Sarah.

Fungal diseases can be transferred from contaminated surfaces or fungal spores can be breathed in. They typically pose more of a risk to people who are immunocompromised and suffer from conditions such as diabetes and respiratory disorders.

There are also other fungi causing global problems too, such as Aspergillus fumigatus, a common mould found in soil, dust and air, with a mutation that makes them resistant to the usual antifungal therapies. Mycologists found that this gene mutation was linked to the use of fungicides in agriculture. Sarah explains that “Normally we think about resistance developing when the patient has been on antifungal therapy for a long time, but many patients are getting Aspergillus infections from the environment that are already resistant to therapy.”

The fungus that Sarah says she is most afraid of is Coccidioides, which causes an infection commonly called Valley Fever, and is typically acquired within desert regions of the southwestern United States, Mexico, and South America. But even this fungus has been found to be spreading to other parts of the United States. “Coccidioides is the most virulent of all fungi and is very infectious. We see it very rarely in Australia, only really in patients who have travelled to affected areas. Handling this fungus in the laboratory puts staff at a high risk of infection, so we have to be very careful with how we handle all fungi in the lab.”

Fortunately, Valley Fever is treatable, and most patients will recover, however people who are immunocompromised are at higher risk of becoming extremely ill.

A global response

WHO estimates that more than 150 million people have a life-threatening fungal disease globally and more than 1.5 million die each year from fungal disease. But Sarah says, “despite this, fungal disease has been neglected in terms of research and funding, development of diagnostics and of antifungal drugs”. Sarah has recently contributed to the World Health Organization's (WHO) Fungal Pathogen Priority List, the first global effort to systematically prioritise fungal pathogens for filling currently unmet needs.

A new cohort

Bringing Mycology into the mainstream has the potential to spark interest from a new generation of people wanting to study and work in the field, which is suffering from staff shortages and lack of funding within research, development, and innovation.

Sarah is hopeful “that this could be something that comes out of the show’s popularity. It has been great for drawing attention to what medical mycologists do and knowing that we're here doing important work. We need more people to develop an interest in mycology to study and work in this field.”

Image: ©HBO - Home Box Office