New Delhi, May 25 -- Attacks on Ebola treatment centers in eastern Congo underscore the serious challenges authorities face - including a backlash in local communities - as they try to stem an outbreak of the infectious disease that has been declared a global health emergency.

On Sunday, Congolese authorities said suspected cases have now passed 900 in the east of the country, mainly in Ituri Province, where the ongoing outbreak is centered. Later Sunday night, angry young men stormed a hospital treating Ebola patients in the town of Mongbwalu in Ituri, the hospital's director said.

The attackers demanded that two bodies of their kin be handed over to them, Dr. Richard Lokudu said. Medical staff scrambled to evacuate the patients as gun...