Becoming a werewolf simply by being bitten by another werewolf as a form of contagion is common in modern fiction, but rare in legend, in which werewolf attacks seldom left the victim alive to transform.

It is not always clear in films whether the bite of the werewolf infects the victim with some disease, or whether the person bitten must first be under some sort of curse. The source of this confusion is easy to understand. Some even state that the consumption of food prepared by a lycanthrope is enough to carry the infection.

To the old folk tale of a god's curse, the modern disease of rabies was added. A person bitten by a mad dog or other animal over time becomes mad, and begins to behave like a beast. Traditionally, all madness falls under the domain of the moon. In movies, the bite of a werewolf acts in a very similar way to the bite of a mad dog.