Q: Do Zombies continue to decompose? If so, how long would it take for decomposition to become such that they are no longer a threat?
A: While there is the possibility that a virus, parasite, chemical, or mutation may slow the process of decomposition in an undead Zombie’s body; it is just as likely that the rate of decomposition would remain the same. When a person’s heart stops pumping blood around their body, the tissues and cells are deprived of oxygen and rapidly begin to die. Different cells die at different rates; an example of this is that the brain cells begin to die within 3 to 7 minutes after death, but skin cells can live up to 24 hours after death and still grow normally in a laboratory culture.
Because decomposition in the air is twice as fast as when the body is under water and four times as fast as underground; a Zombie’s rate of decomposition is very situational.
The human body is packed with millions of micro-organisms that don’t die with the person. These organisms start to break down the dead cells of the organs and slowly, but surely, turn us to “soup”. If creatures, such as maggots and beetles are exposed to the body; the potential for a more rapid breakdown of tissues increases greatly. Within 1 year all that would be left of a body is a skeleton and small remnants of tissue stuck to bone.
An infectious Zombie would most likely pose a threat regardless of how decomposed or not they are. Due to the usually high infectious nature of most Zombies it is advised to never consider them “safe”. The type of threat that a Zombie poses is something that does change over time. A fresh Zombie (still capable of walking or crawling) is an active and advancing threat. A Zombie that can no longer move poses a more hidden and sneaky threat, and a Zombie rotted near to nothing poses a “poison” threat to any nearby water sources, soil, etc.