BUNIA, July 3 -- The treatment center in Ituri province that enrolled its first patient on Thursday is the only site in the world currently testing experimental drugs against the Bundibugyo strain of Ebola. Six weeks into an outbreak that has infected more than 1,400 people and killed 438, clinicians across three affected provinces in eastern Congo have had only fluids, fever management, and isolation to offer. The trial does not provide an approved cure. What it does, for the first time, is create a mechanism to find one.

International health officials had been pressing for this research since the Bundibugyo virus disease outbreak was declared simultaneously in the Democratic Republic of the Congo and in Uganda on May 15. The World Heal...