DAR ES SALAAM, Dec. 31 -- WHEN I first stepped into Nduta Refugee Camp ten years ago, I thought I understood medicine. But nothing in my training prepared me for the reality of a refugee camp, where illness piles on top of trauma. I remember being struck not only by the number of sick people but by its diversity: skin diseases, diarrheal diseases, infections, chronic conditions, often all within the same family. It was overwhelming, and it changed me instantly.

People had fled with whatever strength they had left. Mothers clutching newborns, they werent sure would survive. Elderly men who had carried their last strength across the border.

Families who had fled Burundi with nothing but the will to keep walking. What struck me most was no...