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FICTIONAL FUNGAL SPECIES DEMONSTRATES REAL CONSEQUENCES OF GLOBAL WARMING

By: Hannah Russell

HBO’s newest hit series, The Last of Us, uses science fiction to highlight very real potential dangers of climate change. Since 1975, Earth’s average temperature has risen by 1.44 degrees Fahrenheit. Scientists predict that by 2070, temperatures will rise another 3.6 to 9 degrees.[1] While the effect of global warming on humans, plants, and animals is well documented, the impact on microorganisms is frequently overlooked in climate change research.[2] Fungal pathogens are particularly thermotolerant, meaning that as temperatures gradually increase, so will the prevalence of fungal diseases that were originally rare or unknown.[3] There are currently no vaccines able to combat fungi, and there is little economic incentive for pharmaceutical companies to invest in anti-fungal research.[4]

The Last of Us forces virulent fungi to the forefront of the climate change conversation as its characters struggle with the extreme and terrifying effects of global warming. The Last of Us features a fictional strain of the very real Cordyceps fungus that, because of increased global temperatures, evolves to contaminate grain supplies and infect humans.[5] While this concept may sound like pure science fiction, it is based on real mycology.[6]

The Science Behind the Fiction

Cordyceps, more fondly known as the “zombie-ant” fungus, infects insects with neurotoxins that cause them to twitch and convulse before “hijacking” their motor systems.[7] The still-alive insect will reject its instincts to “summit” a nearby plant, where the fungus then begins to eat the host from the inside until a long cordyceps stalk grows from the corpse.[8] Other insects pass through the airborne spores, causing the cordyceps cycle to begin again.[9] Like insects infected with cordyceps, any fungus-ridden humans in The Last of Us begin to twitch and convulse before turning terrifyingly cannibalistic.[10]

Although an interesting concept for television, cordyceps currently cannot infect humans because of our high internal body temperatures but that does not mean other fungi do not have the potential to do so.[11] One fungus, Candida auris, reflects some of the fictional properties of cordyceps and poses a new concern for infectious disease physicians.[12]

An Urgent Antimicrobial Threat

The Center for Disease Control (CDC) recently released that C. auris is an urgent antimicrobial threat, meaning that there are few to no substances that can kill the fungus or stop it from growing and causing disease. [13] In addition, the World Health Organization (WHO) identified the fungus as a critical priority in its first-ever priority pathogens list published in 2022.[14] C. auris is the only known fungus able to spread from person-to-person, and it has been reported in over thirty countries’ healthcare facilities since it first emerged in 2009.[15] In the United States alone, the annual number of cases has increased by 95% since 2019.[16] C. auris is both deadly to immunocompromised individuals and is multi-drug resistant, leaving doctors with little to no treatment options.[17] To make matters worse, “fungi are more closely related to humans than viruses or bacteria,” so developing a treatment that doesn’t harm human cells is challenging.[18]

C. auris is also an example of how fungal evolution can potentially affect the law as much as medicine.[19] The Occupational Safety and Health Administration (OSHA) has already published how health care employers should respond to C. auris exposures and outbreaks to avoid liability.[20] Disabled or immunocompromised employees could have additional protections under the Americans with Disabilities Act (ADA) and the Family and Medical Leave Act (FMLA).[21] If an employee has a disability like breathing impairment, an employer may have a duty to remedy the situation by either providing ventilation or reassigning the employee to a different role.[22] Additionally, if an employee is immunocompromised because of a serious illness, they may have a right to take unpaid medical leave.[23]

Fungi comprise an entire kingdom of life on Earth that is overlooked in both climate change and infectious disease research. As cordyceps and other fungi adapt to global warming, their ability to withstand increasingly hotter temperatures primes them to be able to infect more organisms. Although fictional, The Last of Us “foreshadow[s] the growing dangers of evolving fungal species” in response to climate change, bringing awareness to an overlooked group with dangerous potential.[24]

[1] Normal van Rhijn & Michael Bromley, The Consequences of Our Changing Environment on Life Threatening and Debilitating Fungal Diseases in Humans, 7 J. Fungi (Special Issue) 367 (2021), https://www.mdpi.com/2309-608X/7/5/367.

[2] See, e.g., id.

[3] Nnaemeka E. Nnadi & Dee A. Carter, Climate change and the emergence of fungal pathogens, PLOS Pathogen (Apr. 29, 2021), https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1009503.

[4] Id.; Isabella Backman, “The Last of Us” Apocalypse Is Not Realistic, But Rising Threat of Fungal Pathogens Is, Yale School of Medicine (Feb. 6, 2023), https://medicine.yale.edu/news-article/the-last-of-us-apocalypse-is-not-realistic-but-rising-threat-of-fungal-pathogens-is/#:~:text=Cordyceps%2C%20or%20Ophiocordyceps%20unilateralis%2C%20is,insects%20like%20ants%20or%20spiders. (last visited Mar. 23, 2023).

[5] The Last of Us: Infected (HBO television broadcast Jan. 22, 2023).

[6] Cody Mello-Klein, The fungal zombies in HBO’s ‘The Last of Us’ are based on real, horrifying biology, Northeastern Global News (Jan. 18, 2023), https://news.northeastern.edu/2023/01/18/the-last-of-us-zombie-fungus/ (last visited Mar. 21, 2023).

[7] Id.; David S. Perlin, Zombie Fungus From ‘The Last of Us’: Is It Real?, Hackensack Meridian Health (Feb. 16, 2023), https://www.hackensackmeridianhealth.org/en/HealthU/2023/02/16/Zombie-Fungus-From-The-Last-of-Us-Is-It-Real#.ZBdyauzMJGp (last visited Mar. 19, 2023).

[8] Mello-Klein, supra note 6.

[9] Id.

[10] The Last of Us: When You’re Lost in the Darkness (HBO television broadcast Jan. 15, 2023).

[11] Perlin, supra note 7.

[12] See Backman, supra note 4.

[13] U.S. Dept. of Health and Human Services, Ctrs. for Disease Control and Prevention, Antibiotic Resistance Threats in the United States (2019) https://www.cdc.gov/drugresistance/pdf/threats-report/2019-ar-threats-report-508.pdf; Antimicrobial, National Cancer Institute Dictionary of Cancer Terms, https://www.cancer.gov/publications/dictionaries/cancer-terms/def/antimicrobial (last visited Mar. 24, 2023).

[14] Antimicrobial Resistance Team, WHO fungal priority pathogens list to guide research, development and public health action 6 (World Health Organization ed., 1^st ed. 2022), https://www.who.int/publications/i/item/9789240060241.

[15] E.g. Backman, supra note 4.

[16] See Meghan Lyman et al., Worsening Spread of Candida auris in the United States, 2019 to 2021, Annals of Internal Medicine (Mar. 21, 2023), https://www.acpjournals.org/doi/pdf/10.7326/M22-3469 (last visited Mar. 24, 2023).

[17] E.g., Backman, supra note 4.

[18] Id.

[19] Guide to HR Policies and Procedures Manuals § 6:49 (2022).

[20] Id.

[21] Id.

[22] Id.

[23] Id.

[24] Backman, supra note 4.