MONSTERS: Mbwiri

The Mbwiri is a Central African demon that possesses people. The person who is possessed is usually the only one who knows that they are possessed. It's said that they target those who aren't living well. People who are possessed by the Mbwiri are usually diagnosed with epilepsy by a doctor.

In order to get rid of the Mbwiri a shaman is called. A hut is built and the afflicted, the shaman, and their assistants will live here till they are cured. For ten days or a fortnight, these people will eat, drink, and dance to the music of flute and drum at the expense of the patient's family. The patient would then dance until the epileptic fits come on. It's said the Mbwiri would hate the good living their victim was having and flee the body. When cured they would then build a fetish house and then avoids certain foods and performs certain duties. Sometimes they don't get cured and are engulfed in madness or runs away to the bush.

SOURCES: 

Wikipedia

Monster Wiki