To find information on healing and spirituality begin looking under Traditional African Medicine and couple it with the word spirituality. This will yield a wealth of information both in the scholarly and non-scholarly literature. Other terms you might want to consider are traditional healers or healing coupled with Africa or African.
Search Tip: Search the word "healing" in the box under the picture of the Encyclopedia. When you have the list of sources choose "African Religions" from under subjects. This search will give you a number of good articles.