“Mama Mtshali” gathered several colleagues to meet us. (South African sangomas like her are easy to spot — they dress in red and white and their apprentices must wear inflated goat bladders in their hair, which I wish all medical students did.)

They showed us how they did diagnoses: Although it involved drumming and chanting, it amounted to taking the patient’s history and checking a long list of symptoms.

We talked about H.I.V.; they were especially interested in how long it lingered on razor blades or porcupine quills, which were their syringes — they cut patients’ scalps and rubbed herbs in.

Then we had a feast of beef liver and sorghum beer and spent the rest of the evening dancing. I could still kick over my head then — that’s how Zulu dances end — but Joao was much better than me.

Mrs. Mtshali and Mr. Muriisa are part of a huge parallel medical system. The World Health Organization estimates the continent has 80 healers for every doctor. (Even in hospitals, it is rare to see an actual M.D. — most care is delivered by nurses.)