My brother does medical research down south for the Govt in Zombie infection diseases. He was just telling me of the latest find that will be published soon in the Bulletin of the American Medical Journal (BAMA).
Seems they have found the reason why some corpses rise up without having been bitten by a zombie. And they are now using the term Zombitus (Zomb-bite-us) for the illness.
There are actually two ways for the Zombitus infection to spread. The classical way is through saliva- normally via a bite. The Zombitus virus in saliva is strong enough to overwhelm a human immune system- normally 30 minutes to 6 hours depending upon the immune system of the victim.
However, when the virus is atomized, such as sprayed into the air, it forms a shell around itself and becomes airborne. It can drift for miles, but if inhaled it settles into the lungs of the victim. In this hibernating form the virus is so weak that a normal immune system can easily destroy it. Somehow the virus is able to know if the host has an active immune system. If it does (as in, if the host is alive) it remains dormant. Once the host immune system begins to rapidly deteriorate (i.e. the host dies) the virus springs into action and floods the dead or dying host with the infection. Reanimation then normally takes from 15 minutes to 2 hours depending upon state of the host body, or amount of viral particles in the host lungs.
This means, that if one is exposed to the airborne viral particles from, say, someone shooting a zombie and splattering his blood everywhere, when he dies (and this can be days to years) he will reanimate.
The CDC should shortly revise its Zombie alert warnings to make sure every dead body had the brain run through from ear to ear- and that people alter methods of Zombie killing to decrease the chance of atomizing zombie blood.
