"According to Bobby Singer, the Buruburu are ghosts born of a person's fear after dying in a terrifying manner. They can then infect others with their fear, and this infection is known as the Ghost Sickness. The people they infect are usually people who have made a habit of terrorizing others. Because it is a type of Ghost, it has all the same abilities and weaknesses as a ghost, but it differs in one notable way: it can be "scared to rest." It is a spirit form first categorized and documented by the Japanese in the Edo period."