The most popular depiction of modern zombies is the viral zombie; highly contagious, can be both fast or slow and motivated to spread the virus through bite and driven by an insatiable hunger for human flesh.

All information here is hypothetical and when the SHTF it is recommended that you keep a diary and make notes of zombie behaviour.

What is a Virus
Viruses are presumed to have been around since life first evolved and there are 3 current theories as to their origins.

• Regressive Hypothesis – Parasitic small cells that attached to larger cells and call only survive with a host.
• Cellular Origin Hypothesis – That viruses evolved from the DNA or RNA that escaped from the genes of a larger organism.
• Coevolution Hypothesis – That they evolved naturally alongside other life.

Popular fiction has also seen viruses borne from other worlds and man made in laboratories.

In the Zombie Survival Guide, by Max Brooks, this virus is called Solanum.

Viruses are the most likely reason zombies will rise, as viruses themselves tread a fine line between living and not living. Outside of a host cell viruses cannot reproduce and are not, technically, alive but due to their interaction with living cells they fall just on the side of a living organism.

All viruses follow the same life cycle of attaching to a host cell, re-appropriating enzymes through genetic manipulation to create more viruses before destroying the cell to release these new copies, which explains the life cycle of zombies quite well also.

Patient Zero
All virus outbreaks share a common starting point with Patient Zero, the person initially infected, who spreads the disease to others. Real life examples can be found for typhoid, Ebola, SARS, Cholera, AIDS and swine flu.

Identifying where infection begun can help in containing and eradicating the virus.

Outbreak Patterns
Most viruses are transmitted through close proximity to someone already infected. Unfortunately people are often most contagious before physical symptoms begin to show.

Infection is most popularly portrayed as transferring between victims through open wounds, such as bite or a scratch but this is not always necessary for viruses to spread. Ingesting contaminated foods or water also carries a high risk of infection.

Depending on how the virus can be transferred and where it starts depends on how likely the disease will threaten humanity as a whole.

In the case of transmission through contact the spread of the disease is limited to how far zombies can walk or run at any given time and how dense the population is. This would be the easiest strain of the virus to contain, but left unchecked it would take around 8 – 12 months for all Continents to be infected and decimate every country within 3 years.

If the virus can be transmitted from human to animal then ticks and rats may carry the disease more quickly, with Continents being infected within 3 – 6 months and humans almost wiped out in less than 2 years.

In a worst case scenario the virus will be airborne and with international transport so quick and popular all continents could be infected within the first 2 weeks and have humanity facing it’s end inside a year.

Most viruses are fragile and cannot survive for long outside a host but some, especially deadly viruses such as smallpox and Anthrax, can survive for years.

Immunization
The normal method of immunizing against a virus is commonly thought not to work in the case of zombies as it is so virulent that even the smallest dose will kill and re-animate the subject.

In the worst case scenario it may become necessary to attempt immunization against becoming a zombie but should be done in supervised conditions by trained specialists.

Try and find a military or medical base if your notes indicate the virus is airborne.

Identifying a Viral Zombie
Viral zombies act like other zombies and are difficult to identify as such initially. Unlike other zombies however, a viral zombies bite will almost always infect and turn the injured person into another of the living dead.

It is not recommended that you go out of your way to check if this is the case but, again, keep a diary and watch the zombies behaviour very carefully. It should soon become apparent if you are dealing with a viral strain of the undead.

It is unlikely that viral zombies will be able to vocalise as they do not breathe, so if one is shouting “Braaaaaaaaaaaiiiiiiiiinnnnnnnsss” at you make sure it’s not just a fellow survivor playing a joke in very poor taste before eliminating them.

Behaviour
These zombies may be both fast or slow and may be dependant upon the ‘freshness’ of the corpse as to how fast they can move, with injury and decomposition slowing them down.

It is likely that zombies would be slow without the heart functioning as blood would collect in the legs and muscles would cease to function as well. That said, it is a zombie, so defies modern science’s explanations to define how they actually re-animate and move around.

The infected person themselves would most likely be driven to spread the infection and try and get close to bite or otherwise injure an uninfected person.

It is also commonly accepted that zombies will also kill humans and eat fresh meat. The necessity of this is unclear as eating the subject incapacitates them from spreading the infection when they themselves rise. It is thought that the newer flesh stimulates the infection inside them as their necrotic flesh dies off or perhaps an instinctive need to eat is triggered by the virus.

Viral zombies would seem to posses limited sight and aural capabilities chasing down sounds and movement. They also do not seem to experience any pain or fear and can use as much strength as the muscles allow without needing to rest or ease up.

Termination
Removing or destroying the brain is an accepted method of halting the body. While the body or both parts may still continue to be undead, without a command mechanism zombies appear to be incapable of continuing a pursuit.

Damaging a zombie by removing limbs should also provide a respite from their attacks.

It is unknown for how long a zombie can continue to function once risen, often it would seem indefinitely until decay eventually halts their spread in the same way removing limbs would.

Stages of Infection
It is most likely that, once infected, the major organs would begin to shut down in the victim culminating in the heart stopping or brain activity ceasing.

At this point the victim would be officially classed as dead but is merely entering an incubation stage while the virus takes over the body. This stage can take from less than a minute to several hours.

Sometime later the victim would become re-animated and ‘controlled’ by the virus.

Surviving infection
The best defence for viral infection is to head to sparsely populated areas. This prevents the spread of the epidemic as quickly and buys more time for a suitable location defence to be set up.

Viruses in Non-Humans
Both flora and fauna are vulnerable to viral infection and can be transmitted via ‘vectors’ such as insects and other plants.

Plants have very effective defence mechanisms against viral infection which often involve killing the surrounding cells to stop infection spreading. These can be seen by the naked eye as large spots. Plants can also produce disinfectants to flush the virus.

When looking for a cure don’t discount plants as a possible source of information.

Why not share your theories on viral zombies in the comments or over on our forums.