In West Africa, the number of deaths from a record outbreak of the deadly Ebola virus has topped 1,200, with more than 2,200 total cases. Liberia, which saw the most new cases in recent days, has imposed a nationwide curfew and sent security forces to seal off a slum housing tens of thousands of people. U.N. agencies have stepped up efforts to deliver food to quarantined areas of Guinea, Liberia and Sierra Leone. Three sickened Liberian doctors who received the experimental drug ZMapp are said to be improving.