In the post-apocalyptic world of “The Last of Us,” a rapidly spreading pandemic in which a mutated Cordyceps fungus transforms people into zombie-like “infected” is besieging humanity. The apocalypse in “The Last of Us” is not real, but a rising threat of fungal pathogens is. It’s possible that viewers will be left wondering if the HBO series’ grim depiction of a different kind of outbreak could become a reality off-screen as the world faces its own pandemic.
The fungus known as Cordyceps, or Ophiocordyceps unilateralis, parasitizes the brains of insects like ants and spiders. According to Scott Roberts, MD, associate medical director for infection prevention at Yale New Haven Hospital and assistant professor of medicine (infectious diseases) at Yale School of Medicine, “fortunately for humanity, while mind-controlling fungal infections make for great television, there is no need to begin doomsday prepping.” However, despite the fact that an unmanageable pandemic caused by fungi is highly unlikely, he continues, fungi can pose a real and troubling threat to humans, and their risk is increasing.
According to Roberts, “very few fungi or mold spread person-to-person, so a fungal pandemic is not very likely.” However, we may face an increase in fungal threats as a result of factors like climate change.
Ophiocordyceps unilateralis, also known as the zombie-ant fungus, is a real-life parasite whose various strains target specific insect species. This is what “The Last of Us” does right and what it doesn’t. The spores of the Cordyceps fungus take over the host’s mind and motor functions, leading to erratic behavior and the insect moving to higher ground, where more sunlight and warmth provide ideal conditions for the fungus’s reproduction. A fungal growth emerges from the host’s head after the insect dies, releasing spores that will target their next prey.
A mutated Cordyceps variant begins infecting humans in “The Last of Us.” Roberts, however, asserts that the transition from insects to humans is highly improbable. This is one of the millions of fungal and mold species that are found in nature and do not infect humans, as he explains. It is impossible for a Cordyceps to infect more than one species of ant.
We inhale thousands of fungal spores when we go outside into the natural world. In most cases, healthy people do not experience any issues as a result. Our healthy immune systems and high body temperatures are to blame for this. The majority of fungi cannot thrive above 98.6 degrees Fahrenheit. According to Roberts, this is the very reason that some mycologists—those who specialize in fungi—posit that we have evolved to have this body temperature.
Infections have the ability to spread from animals to humans in some cases. For instance, humans were infected with the viral disease mumps through contact with small mammals. However, that is not the case for the majority of bacteria, fungi, or viruses, says Roberts. Only a small number of them concern me. Cordyceps are not included in this.”
In the show, the infected food supply was how the mutated Cordyceps quickly reached humans. It is true that the bacteria Salmonella and norovirus that we consume can infect us. However, according to Roberts, ingesting fungus or mold poses little risk of health issues. Probiotics and supplements even provide many of us with access to fungal flora. For instance, the lifestyle website of actress Gwyneth Paltrow featured a widely criticized recipe for a $200 breakfast smoothie with Cordyceps. Furthermore, even if a harmful fungus were to enter our meal, it would most likely be eradicated by the microwave or our stomachs’ low pH.
There are very few instances of fungi spreading between people, even if a mutated fungus does manage to infect a human. According to Roberts, viruses are designed to spread from person to person—we sneeze, and it can infect 20 people in the right environment. Inhaling spores or having an open wound are two ways that fungal infections spread from the environment. Additionally, there is a very low chance of contracting the disease from an infected individual.
In addition, some fungi, like psilocybin, can alter human consciousness. Fortunately, these effects subside once the fungus is eliminated from the digestive tract. Fungi can definitely alter our thoughts, but not in a long-term way, says Roberts. That does not appear to be a possibility, in my opinion.
The majority of fungi species do not pose a threat to humans, but a few can cause issues, and the risk of fungal diseases rises with temperature. Aspergillosis, Histoplasma, Blastomyces, and Coccidiosis are a few examples. They rarely infect healthy people; the most vulnerable hosts are those with compromised immune systems. Additionally, the majority of the time, the infection can be eradicated by existing antifungals.
However, despite the fact that a mushroom apocalypse is unlikely, the risk of fungal diseases is increasing. Roberts cites the rising use of antibiotics as one factor in this. He explains that taking antibiotics “essentially wipes out all of the good bacteria, so fungi can start to take over,” which is a significant risk factor for fungal and yeast infections. The rising number of elderly and immunocompromised people in the population is another factor. Even though procedures like organ transplants and chemotherapy save lives, they also weaken patients’ immune systems. People are living longer than they did in previous decades.
Cordyceps evolve and adapt to human body temperatures in the “The Last of Us” universe as temperatures rise. Inquisitively, this is somewhat analogous to reality. Another factor that increases the likelihood of fungal diseases and has given rise to a troubling pathogen is climate change. As an infectious disease physician, Candida auris, a relatively new fungus, is something that concerns Roberts. This organism spreads one individual to another, which hasn’t actually been accounted for previously.” The fungus, first discovered in 2009, thrives at higher temperatures and may indicate the growing threats posed by evolving fungal species. It is possible for C. auris to cause serious infections once it enters the bloodstream.
Because of their reputation for causing yeast infections, other fungi from the Candida family are frequently found in healthcare settings. But Roberts is concerned about C. auris for three reasons. First, patients can spread the disease to others, which has resulted in outbreaks in nursing homes and other health care facilities. Second, it is frequently multidrug-resistant, rendering clinicians without options for treatment. Lastly, he is concerned about the fungus’s novelty. It suddenly appeared on multiple continents ten years ago, he claims. Because of this, we believe that climate change was probably one of the reasons it happened.
More than 30 nations have reported cases of the fungus. C. auris is not a problem for healthy people. However, it can be fatal for immunocompromised individuals. He also responds, “Probably not,” when asked if health care facilities are prepared for larger C. auris outbreaks. He hopes that over time, researchers will be able to create new antifungals that work better, but unfortunately, pharmaceutical companies are currently not very motivated to invest. Paxlovid, a drug used to treat COVID-19, is profitable and will be used by millions of people every month, he claims. The majority of pharmaceutical companies do not wish to invest in an antifungal that will only be utilized by a select few immunocompromised patients. Additionally, it is more difficult to develop an antifungal that does not also harm human cells because fungi are more closely related to humans than viruses or bacteria.
Even though “The Last of Us” may be more fiction than fact, infectious disease specialists are thankful for the increased awareness of fungi, according to Roberts. Although the show may not be realistic, pathogens like Candida auris are likely to receive more media attention now,” he states. That will only be of assistance to us.
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