The Center for Disease Control and Prevention, the main national public health institute in the United States, has a zombie preparedness guide. When I first heard this, I was more than a little concerned. I always thought zombies were just a fun and wildly popular horror movie genre. But could a zombie apocalypse really happen?
Does a Zombie Virus Really Exist?
The concept of zombies, or bodies reanimated after death, originated with Haitian slaves in the 1600s and 1700s who felt trapped in their own bodies and without the free will to decide their own movements. Stories of the undead eventually worked their way into the Haitian Voodoo religion which suggested sorcerers could use them to carry out their dirty work.
From the undead Haitian slaves of 400 years ago to the present day zombies popular in television and film, zombies usually share a few common traits. They have no sense of right and wrong, no ability to plan, and no impulse control, all of which indicate a lack of a functioning frontal lobe of the brain. They do, however, still have basic motor control and are driven primarily by hunger.
While there are no viruses that can cause neurons to fire in an already deceased brain and thus reanimate a corpse, there are infectious diseases that mimic some of the standard zombie characteristics while a patient is still alive. In particular, a genre of viruses called neurotropic viruses attack our brains and can make us act strange or aggressive.
For example, rabies is spread by a bite (which will sound familiar to zombie movie lovers) and, once contracted, strictly affects the brain leaving its victim aggressive and looking to bite others. In the United States, one person dies from rabies every 9 minutes.
Another neurobehavioral disorder, Kluver-Bucy syndrome, has symptoms that include hyperorality (the urge to put inappropriate things in your mouth), an inability to recognize normal objects, dementia, and a tendency toward a confused, catatonic state while being prone to violent outbursts. Encephalitis lethargica, also called "sleeping sickness," causes hallucinations and puts its sufferers into a catatonic state while making them prone to violent outbursts if roused.
And while a real zombie virus does not currently exist, viruses do evolve. It is feasible that one could evolve, for example, if two viruses infect the same cell, to cut off higher brain function and induce starvation. Infectious diseases can also have mutations just as our regular genetics can which can give the disease an advantage. But a virus evolving into something that can affect even a dead body remains science fiction.
Would We Survive a Zombie Virus?
Whenever a new virus is introduced into a population where there is no immunity—think of the measles and smallpox brought to the Americas in the late 1400s from Europe—the virus is incredibly efficient at claiming its victims. The good news is that since, at least according to lore, a zombie virus would not be transmitted through the air, there is a higher chance of containing it.
In work presented at a recent meeting of the American Physical Society, scientists used standard disease models to estimate the ideal escape during a zombie outbreak. They assumed you needed to be bitten to become infected and that zombies can only walk (and not, say, take public transportation). The modelers determined that the Rockies would be the safest place to go since there are not a lot of people already there and they are challenging to get to. Big cities are the worst places to be immediately after an outbreak but about a month later, they become safer as the infected move outward. You can check out the scientists’ interactive tool called Zombietown USA on the code sharing site github where you can tweak input parameters like zombie speed and kill-to-bite ratio to see how fast the infection would spread.
Zombies in Real Life
While we only know of human viruses that cause at most zombie-adjacent symptoms, there are certain fungi in the plant and animal kingdoms that cause their hosts to act like zombies. A fungus known as ophiocordyceps likes to invade the bodies of insects like ants and takes over its host in just a few days. The ant is then forced to climb up high and settle itself on a leaf overlooking the forest. Once the ant dies, the fungus bursts out of its head so that it can fall to the forest floor below and spread its spores widely in the process.
It is certainly unsettling how the fungus can have so much control over a much more complex organism (the zombie ant) and so quickly. Entomologists believe the fungus appears to manipulate the ant’s nervous system and control its neurotransmitters, like dopamine, which ultimately affects the ant’s behavior.
The CDC's zombie preparedness tips happen to be the same tips that you would use in any emergency, like an earthquake or a blackout.
There is a parasitic wasp Glyptapanteles that lays its eggs in the bodies of caterpillars. After those eggs hatch, the wasp larvae eat the caterpillar’s body fluids and then, eventually, eat their way out. Amazingly, the caterpillar doesn’t die in the egg laying process and instead becomes a sort of zombie guard, warding off would-be predators from the larvae.
So if zombies are still a far-fetched concept for humanity, what about that guide from the CDC? Why would the CDC invest time in science fiction? Well it turns out that the zombie preparedness tips offered in the guide just happen to be the same tips that you would use in any emergency, like an earthquake or a blackout. The CDC uses the theme of zombie preparedness to engage the zombie-loving public in general preparedness planning and has found the technique to be quite effective.
Thinking about fantastical issues like a zombie virus epidemic also leads us to learn more about the capabilities of the human brain and body, as well as how diseases spread versus how to contain them.
Until next time, this is Sabrina Stierwalt with Everyday Einstein’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Everyday Einstein on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com.
Image courtesy of shutterstock.
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