Now how

How could a zombie apocalypse actually happen?

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ALL OF HUMANITY.

What?

The first rule for surviving a zombie apocalypse varies from person to person. For some, it’s “Never believe that you’re safe,” for others, it’s “Don’t travel alone,” and for Jesse Eisenberg in Zombieland, it’s simply “Cardio.” One rule that should always be kept high up in the survival guide, though, is “Know what you’re dealing with.” Although popular culture is trying to convince us otherwise, a zombie apocalypse in which the monsters being faced are reanimated corpses is in fact impossible. But maybe if the zombies acquired their taste for human flesh and severe anger management issues as the result of a terrible virus, such as a mutated strain of debilitating neurological disease or an immunization made from a live virus with unknown repercussions, then there are a few things that perhaps we might want to take into consideration.

Why?

With the zombie craze taking over the media (The Walking Dead, Warm Bodies, 28 Days Later, World War Z, I Am Legend – not even a beloved classic novel could escape when Pride & Prejudice & Zombies was written), zombie theorists are convinced that this is a terror we should be preparing for. Just like in 2012 when there were those who believed that the ancient Mayans had predicted the end of the world and rented underground doomsday-prepared bunkers, there are those who are prepping their zombie survival teams. Before we all jump on the band wagon, though, it’s important to understand the scientific possibility (or impossibility) of a zombie apocalypse occurring in reality.

How?

A virus that can throw people into violent fits of rage is not a novel concept. During the acute period of rabies, a virus that infects the central nervous system, victims go into delirium, have hallucinations, and exhibit abnormal, often violently aggressive behavior. However, unlike most portrayals in the media which show people transforming into zombies within minutes of infection, rabies requires a long incubation period that can last several months before any of these serious symptoms begin to form. The virus must take the time to travel from the site of infection to the brain by moving within the nerves (“Rabies”).

Well, is it possible that the rabies virus could mutate in a way that would increase its similarity to a hypothetical fast-infecting zombie virus?

When a person contracts a virus, the microscopic virus does not just sit there in the body; it latches onto one of the person’s host cells, sucks out the pre-existing DNA, replaces it with its own viral DNA, and replicates itself in the cell. The virus then rapidly repeats this process, producing billions of copies of itself each day. Through this prolific process, the virus often makes errors in its replication. If the virus is a DNA virus, meaning that its genetic information is encoded in the stable DNA molecule, the host cell can verify viral DNA replication and correct any replication errors. However, rabies, like influenza and HIV, is an RNA virus that does not have this self-correcting step in its replication process.  Without self-correction, these replication errors could translate into mutations of the virus’s genetic code (“Viruses and Evolution”). Okay, so maybe it could remotely be possible that the rabies virus could develop a mutation in this way that would drastically shorten the incubation time, inducing its ravaging symptoms within hours or even minutes.

But, in order for the rabies virus to trigger an entire zombie pandemic, it would also have to be much more contagious than it currently is. In television and movies, zombie viruses tend to be airborne. Rabies, on the other hand, is transmitted through saliva during the acute stage of the disease, after the virus has moved from the brain to the salivary glands. Rabies is typically contracted through the bite of an infected animal, but the infection does not continue to get passed on from there unless the infected person transfers saliva to another person. The influenza virus, though, can be contracted through the air. If rabies somehow took this trait from influenza, this could begin the makings of a zombie virus.

Viruses are indeed capable of exchanging genetic material either through recombination or reassortment. In viral recombination, covalent bonds within the nucleic acid (the “NA” in DNA and RNA) of two viruses are broken so genetic information can be exchanged; the bonds are then reformed after the transfer. In viral reassortment, two variants of a virus infect a single cell, and the replication process results in a virus with some segments from one parent virus and some from the other.  Recombination occurs in DNA viruses and RNA viruses with a DNA phase, whereas only RNA viruses can undergo reassortment (Hunt). Note though that these processes only occur naturally between different forms or strains of the same virus. And so, while it is possible for viruses to exchange genetic material, in actuality, viruses only assemble parts that belong to themselves, and rabies and influenza are just too radically different for such a sharing of genetic material to occur.

A hybrid rabies-influenza virus, although it cannot happen in nature, with modern engineering techniques, could be theoretically possible (albeit extremely difficult). As Dr. Samita Andreansky, a virologist at the University of Miami Miller School of Medicine says, “‘Sure, I could imagine a scenario where you mix rabies with a flu virus to get airborne transmission, a measles virus to get personality changes, the encephalitis virus to cook your brain with fever…and throw in the ebola virus to cause you to bleed from your guts. Combine all these things and you’ll [get] something like a zombie virus’” (Than). Nature, though, does not allow all these things to happen at the same time and with today’s technologies, the most likely result of any attempt at combination would simply be a dead virus.

So?

Unless there’s a brilliant and evil virologist out there developing new techniques for engineering such a near-impossible virus, you might want to think twice before buying that crossbow and stocking up on canned goods.

 Written by Constance Kaita

Works Referenced

Hunt, Margaret. “Virology – Chapter Five: Viral Genetics.” University of South Carolina School of Medicine: Microbiology and Immunology On-line. 26 April 2010. Web. 21 June 2013.

“Rabies.” Centers for Disease Control and Prevention. 3 June 2013. Web. 21 June 2013.

Than, Ker. “‘Zombie Virus’ Possible via Rabies-Flu Hybrid?” National Geographic. 27 October 2010. Web. 21 June 2013.

“Viruses and Evolution.” The History of Vaccines: A project of The College of Physicians of Philadelphia. n.d. Web. 21 June 2013.

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