When you wish upon a black person...
It's never stated where in "Africa" the woman is from. The only thing you ever learn about her is that she's a nurse (which is, don't get me wrong, a respectable profession). But she's basically the "Magical Negro" (TV Tropes). She's the vaguely different character who is more in touch with nature that helps the white person by giving him "deep spiritual wisdom" (TV Tropes). It's not okay to treat other cultures that way.
Message
Black people have magic powers and will help you get through illnesses. Or, operations are scary and dangerous.