Adam Nossiter

Health workers here say they are now battling two enemies: the unprecedented Ebola epidemic, which has killed more than 660 people in four countries since it was first detected in March, and fear, which has produced growing hostility toward outside help. Workers and officials, blamed by panicked populations for spreading the virus, have been threatened with knives, stones and machetes, their vehicles sometimes surrounded by hostile mobs. Log barriers across narrow dirt roads block medical teams from reaching villages where the virus is suspected.