The British Medical Journal has released an informative, peer-reviewed study on zombies as part of their Christmas 2015 edition. These undead troublemakers are complex creatures, with variable methods of infection. As the report states, they have become a “dominant part of the medical landscape,” and so have to be considered carefully. It's probably worth pointing out that this study is decidedly tongue-in-cheek, and references both zombie fiction and real-life pathogens.

In fiction, the basic premise of a zombie is that their related virus is primarily passed on through the mixing of infected bodily fluids with non-infected blood, normally through a bite. Although reanimated corpses have been noted to date back centuries, these slow-moving, decomposing disease carriers have been eclipsed somewhat by the emergence of the “rage” zombie. Fast-moving, and with the infection possibly airborne in some cases, these are a far more immediate threat to human populations.

An extremely notable outbreak of rage zombies decimated London back in 2002 – at least in the world of film – which led to the quarantine of the entire British Isles. This zombifying virus caused severe hemorrhaging, and was, in fact, a modified version of the Ebola virus.

Image credit: “Om nom nom” is the only thought going through a zombie’s mind. RAYBON/Shutterstock

Regardless of the type of zombie, the incubation period – the time between initial infection and the appearance of symptoms – appears to be highly variable in the movies, ranging from mere seconds to days. During this period of time, the infected may clinically die then reanimate, or they may remain alive and simply become highly aggressive and cannibalistic.

The infection mechanism appears to also be quite variable. Although most zombies transmit the virus through biting, transmission via insects, animals, and a particularly unusual condition that causes everyone – regardless of whether they have been bitten or not – to reanimate as a zombie after death have also been observed. Forty species of mosquitos in the real world are already responsible for spreading viruses, including the West Nile Virus, so the transmission of a zombifying virus isn't too implausible.

Zombification is not only induced by viruses, though. The most recent candidate for inducing many types of zombie-like behavior in hosts is in fact a real fungus: Cordyceps, found mostly in tropical, humid regions in Asia, is known to infect a variety of insects and takes over their nervous system. In the case of ants, the fungus causes them to climb up vegetation before erupting a spore-shedding spike through their heads, which helps spread the fungus to more ants.

Containment of an outbreak of zombies always appears to be incredibly difficult. As is common in movies, even when the zombie or zombie pathogen is contained within a laboratory, haphazard safety protocols always seem to result in the infection getting outside. If you find that you do need to defend yourself from zombies, a separate numerical modeling study suggests that you should head for mountainous regions – and use your brains before they get eaten.

“The literature reviewed showed a number of creative ways to stop zombies,” Dr. Tara Smith, an associate professor at Kent State University and author of the study, told IFLScience. “During the Zombie Wars, a 'lobotomizer' was created to take out zombies, essentially a combination shovel/battleaxe. If you don’t have one of those on hand, a baseball bat, axe, sword, or even a large tree branch can be used.”

As for what zombies have got to do with Christmas? “They’re probably about as welcome at the dinner table as many readers’ in-laws,” Dr. Smith added.