NEW YORK, Sept. 25 -- In a tent clinic in Zalingei, Central Darfur, patient admissions climbed 22 percent between January and April this year. Not because disease was spreading faster than before (though it was), but because the facilities that used to treat those patients before they reached Medecins Sans Frontieres had shuttered. Forty-five health centers in the region closed in May alone, after the United States Agency for International Development stopped transferring funds to the organizations running them.

On Thursday, MSF brought that arithmetic to the United Nations General Assembly in New York. The medical organization urged governments gathered for the high-level week to treat Sudan's collapsing health system as an emergency re...