“The Last of Us” on HBO envisions a pandemic with a twist: It’s a fungus, not a virus that wipes out much of civilization with terrifying speed.
The pathogen takes over the brains and bodies of infected people, turning them into violent monsters that sprout tendrils from their mouths. Some eventually mutate into creatures with mushrooms growing out of their skulls and over their faces.
The hit series is science fiction, but could a pandemic caused by fungi happen in real life?
Not in the way “The Last of Us” portrays it, with a fungus that currently infects only insects mutating into a threat for humans when it learns to survive in higher temperatures, experts say.
“It’s a show and I don’t think people should get obsessed that their brains are going to be eaten away by a fungus in the near future,” Dr. John Perfect, chief of the division of infectious diseases at Duke University School of Medicine, tells TODAY.com.
“It’s an interesting story, but they don’t need to hold their breath that even with global warming, these fungi are going to take them over. That’s a big jump, even for me who has to deal with fungi all the time.”
But Perfect, who has been studying fungal infections for decades, warns existing pathogens can cause life-threatening diseases, with some strains becoming resistant to the limited anti-fungal drugs currently available.
Some doctors believe a fungal pandemic is already underway with the emergence of Candida auris, a fungus that was discovered in Asia in 2009 and has since spread around the world. The Centers for Disease Control and Prevention calls it “a serious global health threat.”
It’s not a pandemic in the sense of COVID-19 where governments shut down society, says Dr. Andrej Spec, an associate professor in the Washington University School of Medicine in St. Louis, Missouri, who specializes in fungal infections.
But it meets the definition of a pandemic — the emergence of a novel pathogen that has spread over the entire planet and caused disease, he notes.
Candida lives on skin and inside the body, but many fungi produce spores to spread, which are inhaled by humans.
“The idea of having a catastrophic fungal outbreak is relatively unlikely, but would be significantly more scary than COVID because COVID spreads through a relatively small space, whereas spores can travel miles,” Spec tells TODAY.com.
“If you are trying to be away from a fungal spore, there is no safe space. The inside of your home still has fungal spores — they still get from the outside just fine. The International Space Station had an outbreak of mold. It’s literally in every environment that humans are and there’s no way to keep it out.”
What is the ‘The Last of Us’ fungus?
The characters in the show reference Cordyceps, also known as Ophiocordyceps unilateralis, a real fungal parasite that’s been called the “Zombie-Ant Fungus” because it infects insects and spiders.
The “brain-manipulating fungus” changes the insect’s behavior and sprouts from its body before killing the host, researchers report.
In real life, it can only infect arthropods, but in “The Last of Us,” it mutates to be able to grow in humans. That’s not going to happen, both experts say.
The human body’s temperature is too high to allow these fungi to grow and humans have a great immune system that protects us against fungal infections since there’s a massive number of microorganisms on our skin, in our gastrointestinal tract and in the environment, Perfect notes.
It’s when the immune system weakens that problems can occur — but not with a fungus so specific to insects, he notes.
“I laughed a little bit,” Perfect says about hearing the show’s concept. “We live in a mass of fungi, millions of species, but there’s only about 200 to 300 fungi that have ever caused invasive disease in humans.”
Can a fungal outbreak happen?
Fungal disease outbreaks — where two or more people get sick from contact with the same source — are rare, the CDC notes.
Fungi are not passed from person to person as easily as viruses and bacteria, and they tend to cause disease in patients who have some dysregulation of the immune system, Perfect notes.
But the World Health Organization says fungal pathogens are a “major threat to public health” as they become increasingly common and resistant to treatment, with only four classes of antifungal medicines currently available.
More than 7,000 people died from fungal diseases in the U.S. in 2021, according to the CDC. But worldwide, that number is 1.7 million deaths per year, researchers reported in 2020, calling it “the silent crisis.”
Despite the growing concern, fungal infections receive very little attention and resources, the WHO noted as it released its first-ever list of health-threatening fungi in the fall of 2022.
Spec describes public awareness of fungal diseases as “virtually non-existent” and notes that when he tells people what he does for a living, they think he’s researching toenail infections.
Many fungi are able to mimic autoimmune disease and lung symptoms — such as chronic fevers, weight loss, cough and shortness of breath — and for many fungal infections, 90% of people are misdiagnosed with another disease when they first see a doctor, he warns.
People told they have an autoimmune disease or pneumonia, but who don’t respond to any therapy or courses of antibiotics should be aware of the possibility of a fungal infection, Spec says.
Risk factors, especially for people who are immunocompromised, include being around dry leaf litter, because it has a lot of fungal spores; exploring caves, because some fungi are spread through spores in bat guano; and being around high concentrations of dried bird droppings, Spec says.
“But a lot of this really boils down to: There’s very little you can do to successfully avoid fungal infection,” he notes. “The risk factor for fungi is breathing and it’s hard not to do that.”
