According to a newly published report from Johns Hopkins’ Center for Health Security, the next major pathogenic outbreak, or pandemic, will have the following features:

• Contagious during the “incubation period,” before people show any symptoms, or when people have only mild symptoms.
• A microbe that most people are not immune to, so there would be a large population of susceptible human hosts.
• No existing treatment or prevention method.
• A “low but significant” fatality rate.

Three of the above features exist in most current strains of influenza, which tears around the world multiple times every year. However, we possess a few ways to help prevent and treat the flu. None of our methods are perfect. With so many strains of the virus, vaccines only tend to help half of the people who use them, while treatment of symptoms mainly helps to slow the spread of the disease. Still, fatalities with the flu generally occur among the elderly, the youngest children, and people with otherwise compromised immune systems.

And a flu makes you feel tired. You want to stay in bed, at home, away from other people.

What if the flu had something of an opposite effect? Made you crazed, gregarious, eager to be around other people? How much more would it spread? Two, three, five times as much? Right now, roughly 20% of the population contracts influenza every year

Influenza, though quite contagious, is still a rather tame disease when compared to other pathogens. And there are so, so many:

The above map from NIAID only shows a small percentage of pathogens — ones that are recently discovered or making a comeback and that are currently affecting human populations.

In popular culture, there are several “types” of zombie: the magical kind (think voodoo), the insane kind (as in 28 Days Later’s rage virus), and the true “undead” kind, where people die and then reanimate, as in the classic Night of the Living Dead film and the TV phenom The Walking Dead.

The existence (now or at sometime in the future) of a pathogen that makes the infected act in some irrational, insane or violent manner is not in question. Rabies, for instance already does this. The Cordyceps unilateralis parasitic fungi essentially takes over an ant’s brain and make it climb to the top of plants and attach itself there with its mandibles so that it is at a high point from which the fungi’s spores can more readily be spread:

The parasite Toxoplasma gondii infects mice and makes them unafraid of felines, and even actively seek them out. The cats eat them, and the parasite reproduces inside the predator. There are also parasites that infect grasshoppers and force them to hop into bodies of water, where fish will eat them provide bodies in which the parasite reproduces.

In his excellent Science…Not Fiction column, writer Kyle Munkittrick breaks down the requirements for a true undead-style pathogen:

1. The pathogen needs to reanimate a “brain dead” person and turn them into a hunter that can move, use its senses, and desires to eat animals and humans.
2. The undead are in a process of ongoing decomposition. So, while the brain and nervous system is reactivated, the infected’s cells continue in their death processes.
3. The pathogen is contagious via bodily fluids — blood and saliva from bites.

What’s more is that this process needs to happen very quickly. However, as with the rabies virus (and virii in general), bodily infection takes some time. The virii have to enter host cells, and then undertake viral genomic replication, transcription, translation, and post translational modification and assembly. It can take days to infect a large animal and reach the point where the viral load is large enough for the disease to be very contagious. So, a victim would need to be infected some time before they died, allowing the virus enough runway to spread throughout their tissues. Then, upon death, the virus somehow reanimates the corpse and the “zombie” carries on with feasting and spreading the disease.

The amount of time needed to reproduce sufficient viral load, though, would make it all the easier for us to both quarantine and treat (if possible) the infected.

One type of pathogen that is incurable and untreatable with current technology and also operates on an insidiously low-key level are prions (proteinaceous infectious particles), an example being Jakob-Creutzfeldt disease, aka “mad cow disease”. These are mutated forms of normally-present proteins that clump together around neuronal tissue, ultimately creating holes in the brains of sheep, cows and humans. The process of infection to onset of symptoms is quite lengthy — 5 to 20 years — but once noticed, death often occurs inside of six months.

Some chance of a zombie-inducing super pathogen may lie in our deep past, as opposed to only awaiting us in the form of a pathogen that has yet to evolve or emerge. As our climate continues to warm, melting glaciers and permafrost, incidences of ancient pathogen reemergence will grow, such as the discovery of a giant-sized virus discovered in 30,000 year-old Russian permafrost samples and reported on in this 2014 article. Called Pithovirus, it seems to only infect amoebas, but there are bound to be thousands of viruses, bacteria, parasites and fungi that are preserved in a dormant state inside ice that will one day melt.

NIAID’s director, Dr. Anthony Fauci, was once the boss of my boss when I worked in medical research almost two decades ago. I had a chance to talk with him for a very brief time, and the man is brilliant. He isn’t just an executive leader: He still actively works on research and policy regarding infectious disease. I was in my early twenties at the time and had been writing screenplays at the time. One of my projects was essentially about a zombie outbreak caused by runaway nanotechnology that infected, mutated and took control of human hosts, so I naturally steered the conversation toward Dr. Fauci’s opinion on such a take on the undead. He remarked that a nanotech origin was just as possible as a biological one, because it would likely also require genetic engineering — i.e. human tampering — to create a pathogen to act like the one Kyle Munkittrick wrote about.

When it comes to full-on reanimated “undead” zombies, I have to agree. Infecting a host, who must then die, and then come back to life, doesn’t seem to make much sense from the life-cycle perspective of a pathogen. If zombies ever do become reality, the most likely cause will be mistakes born of human curiosity or anger.

While we wait, I suggest we all invest in one of these zombie-proof cabins.

Thank you for reading and sharing!