Daniel Berehulak/The New York Times

Dennis Khakie, who had tested positive for Ebola, celebrates as he walks out of the “confirmed” ward after receiving a negative laboratory testing for the virus at the Bong County Ebola Treatment Unit near Gbarnga in rural Bong County, Liberia.

In the newly opened treatment center, Western volunteers and Liberian workers identify who is infected, save those they can and try to halt the virus’ spread.