A bitten human (or any human that has had zombie tissue or bodily fluids introduced into their body) will certainly reanimate into a zombie. Speed of the transitition depends on the overall health of the host, proximity to a major blood vessel, and type of zombie attacker. Killing the human before he transforms is almost always the safest option, but it is rarely easy, as humans tend to bring their loved ones along or develop strong emotional bonds in the process of depending on one another. The emotional attachment may cause irrational actions, such as refusing to acknowledge the inevitable change. Disputes over killing infected humans are one of the leading causes of survivor group failures.