For a zombie apocalypse to happen, you need two things: Something to turn people into zombies and a way this can be transmitted from person to person. Without transmission, any zombie outbreak will have, if you excuse the pun, little bite to it, and this is what I want to consider here. So what do I mean by transmission? Well, transmission is how whatever’s turning people into zombies gets from one person to another. The method of transmission will determine both how easily it can spread and how easy it will be for you to avoid picking it up. Here, I’m primarily thinking of diseases or parasites that turn people into zombie-like creatures, whether natural or man-made) rather than something that would raise the dead (this is because I’m trying to keep it biologically feasible). Also, I’m not going to consider other things that could turn people into zombies (such as chemicals).
So how could a zombie disease be transmitted? The traditional route is through a bite that breaks the skin, allowing saliva from an infected person to get into the blood stream of someone they attack. This is certainly a well-established way of diseases passing from one person to another. For example, this is the way that rabies (probably the closest thing in the world today to a real ‘zombie’ disease) is transmitted from one person to another. However, transmission through bites is actually quite an inefficient route for a human disease to move between victims. This is because human teeth are pretty poorly adapted for biting and you have to bite someone pretty hard to get through the skin. Also, this mode of transmission would be easily foiled by something as simple as a thick leather jacket (think of the kind stuff that bikers traditionally wear). This means that any zombie disease that only spreads through bites will spread slowly, at least at first. Only once you have a critical mass of infected people will it really take off. It would also be quite easy to avoid picking up a zombie disease from a bite – you just don’t let someone who’s infected close enough to get their teeth into you.
Other less tradition routes of transmission could allow a zombie disease to spread both with greater ease and much, much faster, making it easier for a zombie apocalypse to get off the ground and bring the world to its knees. For example, a disease can also spread through contact between bodily fluids and what are known as mucosal membranes (things such as eyes, noses and mouths) or existing wounds. This would mean that someone could get infected not just from a bite but also from things like blood and saliva getting onto your face when you’re bludgeoning in the head of the person trying to bite you. This mode of transmission features in the film 28 Days Later (one of my all time favourite post-apocalyptic stories ) where one of the characters is infected with the rage virus by a drop of blood falling into his eye, and would allow the disease to spread a lot quicker and easier. This is because killing people infected with a zombie disease will be very, very messy and there will probably be blood and guts flying everywhere. It will be much harder to protect yourself because all it needs is one drop of blood to end up in the wrong place and you’ll be a goner.
Similarly, a zombie disease could go air-borne. This would make just being in the proximity of someone who is infected very dangerous, after all they wouldn’t need to bite you, just breathing in your general direction might be enough. If this is the case, you’d probably never want to go outside without a face masks and filters to avoid catching it. As we all know from our own experiences with flu, air-borne diseases can spread very fast and one person can infect many, many others in a very short space of time. This makes the prospect of an air-borne zombie disease extremely terrifying. I mean, what if it was as easy to pick up as the common cold?
There’s also the possibility that a zombie disease could be water-borne. Take something like typhoid or dysentery. These are normal diseases you can pick up from unclean water but what if you could contract a zombie disease in the same way? If this were true, one infected person could infect many, many others without even going near them. It would also be much, much harder to avoid – All you drinking water would have to be passed through something like a reverse osmosis machine to filter out the disease before you’d know it was definitely safe to drink and such machines are not exactly common outside of the sailing community. Just think what would happen if the public water supply somehow got contaminated (maybe by the body of an infected person ending up in your local reservoir). This means that a water-borne zombie disease could start an epidemic very easily. However, there’s still at least a chance you could avoid catching it if you have the right equipment.
The last possible mode of transmission I want to consider is a vector-borne zombie disease (something my fellow writer Jack Flacco reminded me about today in a comment on another of my posts). This is a disease that can be spread not just from bites from other people but by bites from other animals too. The vectors wouldn’t catch the disease so they wouldn’t become zombie animals; instead they’d just transmit it from one human to another. Think malaria and mosquitoes here. A vector-borne zombie disease would be truly frightening and almost unstoppable. One vector could infect many, many people and, depending on what the vector is, it could be almost impossible to avoid them. Almost anything that is small and feeds on human blood could be a vector for a zombie disease but I’m only going to consider two of the most common: Ticks and flying insects.
If a zombie disease was transmitted by ticks (small, blood sucking relatives of spiders), then it’s likely to spread slowly but inevitably, especially in areas of open countryside (the model here is something like Lyme disease). However, they are relatively easy to avoid by keeping away from such habitats and doing things like making sure you don’t leave your legs uncovered. With a tick-borne zombie disease, what you’d probably see is the disease flaring up here and there on an unpredictable basis. This would make fighting it very difficult as we’d never know where it would strike next.
If a zombie disease was transmitted by flying insects, we’d see a very different pattern of infections. Once someone in an area got infected with a zombie disease, it would rapidly spread from person to person whenever an insect bit one person and then another. This would result in a disease front that spread rapidly across a region. People fleeing from infected areas would only make the spread happen faster. And no matter where you were, you’d never be safe from the risk of infection. I mean, have you seen how hard it is to keep every mosquito, midge or fly out of your house on a hot summer’s night? A zombie disease that was transmitted by flying insects would be a truly terrifying prospect because it would be virtually impossible to either stop or avoid.
So what’s the conclusion of all this? Well, if a zombie disease were to ever appear, you’d better hope that the only way it’s transmitted is through biting as that will give you your best hope of being able to both avoid it and beat it. If it develops the ability to spread by any other means (and why wouldn’t it since many other diseases do?), you might not believe it to be possible, but you’ll be in even deeper trouble than you were before!
From the author of For Those In Peril On The Sea, a tale of post-apocalyptic survival in a world where zombie-like infected rule the land and all the last few human survivors can do is stay on their boats and try to survive. Now available in the UK, and available as an ebook and in print the US from the 21st March 2013. Click here or visit www.forthoseinperil.net to find out more.