In Things Fall Apart, why did the medicine man drag the corpse of the dead ogbanje child into the Evil Forest?

The reason behind this action is the Igbo belief that an ogbanje is a child who continues to return. Ekwefi, Okonkwo's wife, had nine babies who died as infants. The ogbanje is called a repeating child, meaning that the same child comes back after death then re-enters their mother's womb and is born again.
One solution to prevent this from happening was to dispose of the dead child's corpse away from society, often in the forest. The healer Okagbue had determined after her birth that Ezinma, the girl who survived, was an ogbanje and recommended they dig up her buried spirit stone, which Okonkwo did. Although her parents worry about her ill health, they are convinced she will stay alive.