Recently, HBO has began premiering a new show based on the popular video game The Last of Us. The show has been a major hit and portrays a world overcome by a disease that essentially turns people into zombies. However, unlike many other zombie infections in pop culture, this infection may be realistic. Over the course of the last few decades, Earth’s climate has been quickly growing warmer, while this may not affect human’s directly, the increased temperature allows diseases to thrive in circumstances they couldn’t normally survive in. According to the CDC, the Danger Zone for bacteria to thrive in ranges from roughly 41 degrees to 135 degrees. The warmer the better, as evident by the amount of diseases prevalent in humid, warm environments such as rainforests. In The Last of Us, a species of fungi knows as Cordyceps (a real fungus) mutated an had the ability to take over the mind of a human. This sounds like science fiction, but in the real world this same fungus has the ability to perform such an action on insects. The Cordyceps’ spores will find their way into an insect, then slowly grown within similar to a parasite, then the invader will control the brain of the insect and grow out of its body to distribute even more spores. The only reason this can’t affect humans is because Cordyceps need a cooler body temperature, however if a mutation occurs as a result of climate change and the fungus is forced to accept warmer temperatures then humans may be next on the menu.
Another issue that the science community fears is that melting of permafrost. Permafrost is present in Arctic environments and is essentially frozen dirt and water that has been this way for thousands of years. Within this environment bacteria and viruses have been frozen in time and if warmed could be reintroduced above the surface. Many of these diseases have been dead for centuries and only preserved in this permafrost. If the permafrost were to thaw, and much already has, then humans could face a whole plethora of new infections and viruses. Traces of DNA/RNA from diseases such as the Bubonic Plague, Smallpox, and the 1918 Influenza virus have been found from melted permafrost.
In the graph above various sources have been identified that threaten humans and our immune systems. Rising temperatures, rainfalls, and floods all provide warm, and humid environments ripe for diseases to mutate or become more deadly. As climate change continue to worsen, overcrowding and migration may also play a huge role in the spread of such diseases. If mass migrations were to occur, more people would be packed into unsanitary conditions and diseases would easily circulate. We see this often after natural disasters occur where people receiving care for their injuries contract deadly diseases through cuts, unsanitary medical equipment, and close contact with people already infected with the infection or virus.