I like zombies. Fictional zombies. Romero’s ‘Night of the Living Dead’ is a classic, and I am fan of ‘The Walking Dead’ and of killing zombies in video games. The rise in popularity of zombie fiction has seen a variety of sources of survival tips including books (‘The Zombie Survival Guide, ‘The Zombie Combat Manual’) and websites. Even the CDC got into the game with a blog post about being prepared for a zombie apocalypse. By now we know how to kill zombies and basic survival tips, but I am intrigued by the initial outbreak. The most popular method responsible for the rise of zombies is a virus transmitted by biting. I understand how people can get bitten after the world is full of zombies; people are slow, overwhelmed by a horde, or surprised. But what about before the world is overrun with reanimated corpses hungry for flesh? Just how likely is it for a virus transmitted by biting to spread and threaten the survival of the human species?

Humans cannot see viruses without the aid of a microscope. Viruses are not living; they cannot grow and reproduce without a host cell. Sometimes during replication, the genetic material will change, and these mutations make it difficult to treat and to cure viral diseases. The genetic material can be either DNA or RNA, and there are different groups of viruses based on characteristics such as shape and behavior. Because viruses are not alive, antibiotics will not kill a virus; antiviral medication has to be developed. Many viruses are specific to a host, so a virus “jumping” from one species to another is rare. In order to transfer to a new species, the virus would likely have to mutate so it can survive in the cells of the new species.

The reason we are not overrun by viral diseases is because viruses are difficult to spread. Several different types of viruses cause the common cold, and to catch a cold, you need to be near an infected person. You have to come in contact with a bodily fluid, like mucus, containing the virus. By washing our hands and avoiding touching our eyes with dirty hands, we stop cold-causing viruses (and other similar viruses) from infecting us. Even viruses that can be transmitted during a common activity like sex have not threatened our extinction because of the steps needed for successful infection: body fluids carrying the virus must enter a new host’s body, invade the cells and replicate, and this process must be repeated by the infected finding new partners. Diseases caused by viruses can be detrimental and deadly, and we are fortunate that there are many obstacles in viral transmissions. If we could become easily infected, then humans could face extinction, which is a common occurrence in zombie fiction.

For a zombie virus to spread to so many, it would probably have to be genetically engineered. We stay away from people we know to be infected; this is why colds happen more during the winter because the weather keeps us inside, closer to each other. HIV spread across the world because we cannot see any obvious visual signs of infection. I don’t know about any of you, but my instinct would be to avoid someone with signs of a zombie infection, and I definitely would not have intimate relations with a zombie. Therefore, I suspect the initial wave of infections would be the result of the release of a virus created in a lab. Genetic engineering is problematic and takes an immense amount of time and resources. Not a lot of the virus would be made; if viruses were easy to make in large amounts, we wouldn’t need missiles and nuclear warheads. So the virus is released. Then what?

If the virus is transmitted by bites, then the virus is carried in a person’s saliva. Kissing is not an effective form of transmission because saliva rarely comes into contact with blood. During this time, the virus cannot show signs of infection so it has time to spread. If the virus is only in saliva and the saliva must come into contact with blood to be transmitted, then biting would be the way to transmit the virus. But what would cause biting to become a worldwide phenomenon? Remember, love nibbles aren’t enough. The teeth have to break the skin, saliva must come in contact with the blood, and the contact must be long enough for the virus to enter the other person’s bloodstream. Genetically engineering a virus that is only viable in the saliva is an ineffective way to engage in biological warfare and to wipe out almost all of the human population.

What if the virus is transmitted sexually? HIV/AIDS first appeared in the early 1980s. In 2010, there were about 35 million people in the world living with HIV and AIDS. Yes, 35 million is a lot, but there are 7 billion humans on the planet. The disease is devastating, but after thirty years, less than 1% of the population is infected. Even if the zombie virus was known, it would still take a lot of time to spread. Then after the infected become zombies, the virus will have to continue to spread to reach the numbers necessary to drive humans to the brink of extinction. However, once zombies started to appear, there would undoubtedly be enough humans and resources left to work on a treatment and prevent an epic worldwide outbreak.

Only a very unique virus could cause the epic outbreak that results in the devastation seen in ‘The Walking Dead.’ But who would spend all of that time and money on such a virus? The danger alone would make the majority of people with the necessary skills turn down that type of project. If the zombie virus was the result of a project gone wrong, then the virus would have to escape the facility, and any worthwhile facility would have protocols in place to prevent such an event. And for a zombie virus to occur naturally, it would probably not be able to spread at the speed required to reduce the human population to the numbers seen in most works of zombie fiction.

Does the unlikeliness of a zombie virus make me enjoy zombie fiction less? No. Again, this is about a zombie virus. Diseases can be caused by other pathogens like bacteria and fungi. And each type of pathogen acts differently. The scenario needed for a zombie virus to almost wipe out the human species is highly improbable, which is why the majority of zombie fiction takes place after the zombies have overrun human civilization. Zombies arrived, humans died, and now the survivors must continue. The story of survival is what makes zombie fiction fascinating for me. How can a select few endure the horror all around them? As long as the zombies are gory, the characters and situations are interesting, and there is a lot of zombie carnage, then I will continue to enjoy the many incarnations of zombie fiction.