The Evil Eye, or Malocchio, is one of the most ancient and widesrpead superstitions of the whole Mediterranean basin. Every culture seems to have their own version of the Evil Eye and their own ways to fight it. One thing they all have in common: the Evil Eye is caused by jealousy and envy. If a person envies you or your family fortunes, s/he may cause a malocchio curse, even without actually meaning it.
My grandmother tells the story of how my aunt was the victim of the Evil Eye as an infant, and got some type of "sleeping sickness" where she could hardly stay awake. Grandma took her baby to a local woman who could foresee the future and "diagnose" the evil eye by dropping olive oil in a bowl of water. The oil formed one large drop in the middle of the bowl, a sure sign of the Evil Eye, but after chanting the right prayers (that only women were allowed to know) the oil broke up into tiny droplets and spread out. The ritual broke the curse of the Evil Eye and my aunt, at least according to the tale, got better immediately.