Author: Sara Habibipour
If you haven’t yet watched HBO’s The Last of Us (or at least played the video game), then what are you waiting for?! Before I start to dive into the infectious disease background behind this story, I just want to mention that it’s an absolutely stunning show, and I highly recommend that you watch it! It’s so addicting!
But, now that I’ve got that out of the way, let’s talk about the realities of fungal infection, as well as how a fungus pandemic can happen now and in the future.
Yes, the Last of Us fungus is real.
The fungus from The Last of Us, is based on a real fungus that exists in nature called Ophiocordyceps unilateralis, or cordyceps, which is
often referred to as “zombie-ant fungus” because it primarily infects insects such as ants and spiders. Its considered “brain-manipulating” because it changes the insect’s behavior and begins to grow itself from the insect’s body before killing it. The image to the right shows cordyceps devouring an insect.
Is this possible in humans?
The Last of Us depicts this fungus mutating to the point where it affects humans and turns them into zombies. This is impossible in humans.
Why? Simply because the human body temperature is too high to allow these fungus to grow.
But, can humans become infected with fungi? Yes, absolutely.
In fact, there are about 200 to 300 species of fungi that can cause infection in humans. On your skin and in your GI tract right now, there are fungi flourishing–although they don’t cause infection–serving as a part of your immune system and providing a healthy environment for bodily functions to occur.
We don’t typically see fungal infection in young, healthy patients. However, perhaps you’ve seen on the news recently, that there have been an increasing number of fungal infection outbreaks occurring in nursing homes. So, fungi do cause more harm for people with weakened immune systems. In fact, an estimated 1.7 million people die from fungal infections every year (Kainz et. al). One of the biggest culprits is Candida auris, a multi-drug resistant fungus that has made its way into the nursing homes I mentioned above. In addition, AIDS-related organisms like Cryptococcus neoformans kill hundreds of thousands of people annually frequently causing meningitis that can cause cognitive dysfunction.
In humans, fungi do not spread as easily as viruses. But the WHO states that fungal pathogens are a “major threat to public health” as, like other pathogens, they mutate and become drug resistant to treatment. What’s even scarier is that we only have four classes of antifungal medicines currently available. Fungal infections receive very little resources and attention, yet the WHO has been continually adding to its list of “health-threatening fungi” since fall 2022.
The Threat of Climate Change on the Spread of Fungal Infections is Very, Very Real.
The Last of Us mentions that the threat of fungal infections increases when the warmth of our environment increases (as fungi prefer warmer habitats). This is true, particularly for Candida auris which, since 2009, has been found in over 30 countries.
In a warming world, fungi also have to adapt to a warmer climate. This means their optimal growth temperatures become more and more similar to human body temperature. In the future, we can likely expect to see more fungal infections in humans than we have ever seen before.
Although fungi would likely not cause a COVID-like or zombie-like pandemic (simply due to how fungi transmit between humans and the types of fungi humans are currently susceptible to), we likely will see a large increase in fungal infections among immunocompromised populations, especially as our world becomes warmer.
Image Sources: https://www.gettyimages.com/detail/photo/dead-adult-calyptrate-fly-by-a-fungus-royalty-free-image/1433206830?utm_medium=organic&utm_source=google&utm_campaign=iptcurl