"A werewolf (Or Lycanthrope) in folklore and mythology is a person who shapeshifts into a wolf, either purposely, by using magic, or after being placed under a curse. The medieval chronicler Gervase of Tilbury associated the transformation with the appearance of the full moon, but this concept was rarely associated with the werewolf until the idea was picked up by modern fiction writers. Most modern references agree that a werewolf can be killed if shot by a silver bullet, although this is more a reflection of fiction's influence than an authentic feature of the folk legends. Werewolves are sometimes held to become vampires after death."
"A recent theory has been proposed to explain werewolf episodes in Europe in the 18th and 19th century Ergot, which causes a form of foodborne illness, is a fungus that grows in place of rye grains in wet growing seasons after very cold winters. Ergot poisoning usually affects whole towns or at least poor areas of towns and results in hallucinations, mass hysteria and paranoia, as well as convulsions and sometimes death. (LSD can be derived from ergot.) Ergot poisoning has been proposed as both a cause of an individual believing that he or she is a werewolf and of a whole town believing that they had seen a werewolf. However, this theory is controversial and unsatisfactory. Witchcraft hysteria and legends of animal transformations, as well as hysteria and superstition in general, have existed across the world for all of recorded history. Even if ergot poisoning is found to be an accurate explanation in some cases, it cannot be applied to all instances. An over-reliance on any one theory denies the diversity and complexity of such occurrences."