Zombies have swept pop culture with shows like “The Walking Dead” and video games like “Left 4 Dead.” The zombie apocalypse has become a phenomenon, and many geeks and fans have fantasized about their own survival tactics. In 2012, the Centers for Disease Control and Prevention utilized the pop-culture phenomenon for a public preparedness and response campaign in case of a zombie epidemic. Although the CDC meant it as a way to promote personal preparedness for all emergencies, this led people to wonder if a zombie apocalypse is actually possible. Many shows, movies and video games have alluded to ways the zombie apocalypse could happen.

Is there any possibility that a zombie apocalypse could happen? If so, what are the real threats that could possibly lead to a zombie epidemic?

Ophiocordyceps unilateralis is a fungus that infects camponotini carpenter ants in the rainforests of Brazil. The spores infect the ants, causing them to stumble around erratically. The infected ants soon move to the underside of a leaf and begin gnawing at its veins. They latch onto a vein, where they soon die. Once the carriers, or ants, are dead, a stalk sprouts from their head to release spores to infect other ants. Although there have been no documented cases of a human being infected by this fungus, which seems relatively selective in which species it infects, could a similar type of fungus eventually infect humans?

Toxoplasmosa gondii is a single-celled parasite that lives in the intestines of cats. The parasite sheds eggs that may infect other animals. This parasite may produce cysts on the brain that can cause odd behavior. If an infected rat comes across the scent of a cat, it will disregard its natural instinct to flee from the odor. The cat’s odor will cause a drastic shift in the chemistry in the rat’s brain; the rat will seek out the source of the odor as if it wants to be ingested by the cat. Humans can be hosts to this parasite by handling cat litter and soil. If this parasite can alter the natural function of a rat’s brain to the point where the creature disregards its natural survival instincts, is it possible that it could alter the chemistry of a human brain?

Anyone who has taken Intro to Microbiology for general education requirements has learned that prions are truly terrifying. Prions cause the normal healthy proteins in human brains to fold abnormally. They are the cause for diseases like mad cow disease. The state of New Hampshire released information on Sept. 5, 2013 that eight neurosurgery patients at Manchester Hospital may have been exposed to Creutzfeldt-Jakob disease. Crueutzfeldt-Jakob disease causes symptoms similar to mad cow disease, which can include changes in walking, confusion, dementia, hallucinations, muscle stiffness, muscle twitching, personality changes and speech impairment. Prions are another organism that can alter human brains, causing the infected to act frighteningly similar to a zombie. There is no known cure for those infected by a prion, and it is not picky on the species it infects.

The most popular belief among zombie enthusiasts is that neurogenesis and stem cell research will give way to the undead walking the earth. In the past, the consensus among scientists was that the brain could not generate new brain cells. However, in recent discovery, generation of new nerve cells through the process of neurogenesis is possible, but there have not been any documented success of completely reanimating a dead brain into a living organ. It seems that even if Frankenstein’s monster were possible, it would not cause an apocalyptic event.

Although the ophiocordyceps unilateralis fungi, the Toxoplasmosa gondii parasite and Creutzfeldt-Jakob disease can cause the infected to exhibit zombie-like qualities, the infected are alive and have failed to rise from the dead to spread the infection on a pandemic scale. Could evolution alter the DNA of these already frightening microbes to reanimate the dead? The only feasible answer to give is that it could be possible, however improbable. It is never a bad idea to be prepared. Zombie apocalypse survival kits can come in handy, whether for the undead walking or a natural disaster. But for now, the world looks relatively safe from the undead.