The basics of the Blues were mostly influenced by African-American culture. The use of flatted notes (the 3rd, 5th, and especially the 7th) comes from the indigenous music of West Africa (although sometimes used in English and Irish folk music). The use of “call and response” lyrics comes from the “field hollers” of slaves and later of sharecroppers.

The West Africa branch is (IMHO) best represented in modern times by the late, greatAli Farka Touré (http://www.allmusic.com/cg/amg.dll)

If you don't know his music, please check it out!
YouTube Playlist (http://www.youtube.com/view_play_list?p=E1BF577E0B34700A&search_query=Ali+Farka+Tour%C3%A9)

Never heard of him. I listened. I liked it.