She first began treating the Nuer tribespeople of Sudan’s Western Upper Nile province in 1989, as an epidemic of visceral leishmaniasis — a deadly, parasite-borne infection — devastated the already conflict-ravaged and malnourished population. In the midst of a civil war, she worked with Médecins Sans Frontières (Doctors Without Borders) to set up makeshift clinics and offer the only treatment option for an area with no health care infrastructure, electricity, or running water.