Freaky fungi: Your patients' newest fear

If your patients have been watching the HBO series “The Last Of Us,” they may have some new health fears about fungi. In the show, zombie fungus turns humans into zombies.

“Zombie fungus” is a real thing—but your HBO-watching patients don’t need to freak out about it just yet. 

The show depicts a fungus, scientifically known as Ophiocordyceps unilateralis, which turns people into zombies. While this may seem like a call for alarm, it’s really “called creative nonfiction,” says Adrian Popp, MD, chair of infectious disease at Huntington Hospital. Notably, the fungus doesn’t work like that for the rest of us. 

In the real world, Ophiocordyceps unilateralis attacks insects, putting them in a zombie-like state where they lose control of their mind and body. It does not harm humans, and scientists haven’t found any fungi in the real world that turns humans into zombies.

“It gets into the ant’s brain and they become erratic,” Popp tells MDlinx. “They don't behave like ants anymore; they behave like zombies.”

A major reason that zombie fungus infects insects, and not humans is that the fungus thrives in cool temperatures and thus impacts cold-blooded creatures, he says. Some researchers suggest that fungi could adapt to warmer temperatures over time.^[]

Fungal infections in the real world

Humans aren’t spared from fungal infections altogether—although, so far, none have been discovered that turn us into zombies—so, when talking to patients about safety, it’s important not to overpromise.

“There are certain fungi, unfortunately, that do infect the brain and that are real—but not the way it showed up in this [TV show],” says Popp.

One particularly dangerous human-attacking fungi is Cryptococcus neoformans, which can enter the brain and cause things like fungal meningitis or death if left untreated, according to the Centers for Disease Control and Prevention (CDC). This infection is rare in people with strong immune systems but more common in people with HIV.^[]

The CDC does not currently screen for C. neoformans but past reports have suggested screenings may be beneficial, at least in people with HIV. In a 1986-2012 analysis, the CDC evaluated samples of people with HIV infections and found 2.9 percent of those evaluated contained C. neoforman antigens.

In addition to HIV, cancer can weaken a person’s immune system and make them more susceptible to fungal infections, as can certain cancer medications like steroids, anti-tumor medications, and post-organ transplant medications, according to the CDC. 

More common fungal infections in humans are candida auris infection, yeast, and mold infections. These tend to cause skin problems in patients with strong immune systems, but can cause more intense immune system disruption for patients who are immunocompromised, says Popp.

Fighting off fungus

Patients with fungal infections should be treated with antifungal medications or be seen by a specialist if they are in need of extra care. When treating a fungal infection, physicians should consider both the fungus they are dealing with and their patient’s current health status, says Popp.

“One has to keep an open mind: think about these things, get the appropriate cultures test, and figure out what you're dealing with,” says Popp. “Once you know what you're dealing with, being a fungus, being a bacteria, being a superbug—being a more resistant fungus—then you have the information necessary to give the proper medication.”

Distilling fungal fears

While you can offer patients the peace of mind that yeast infections won’t turn them into zombies, there are other things you can’t promise them. Like fool-proof protection from the human-infecting fungi that are out there already.

“The truth is, we live in a dirty world,” says Popp. “Everywhere around us there are bacteria and fungi and we’ve adapted to live among them. The problem becomes when they go into places that they're not supposed to, and it becomes an infection.”