Emmanuel Tucker, right, site engineer, discusses progress on the Zorzor Ebola treatment unit with Sam Sells, military liaison for U.S. Agency for International Development, in Zorzor, Liberia, Nov. 18, 2014. United Assistance is a Department of Defense operation to provide command and control, logistics, training and engineering support to USAID -led efforts to contain the Ebola virus outbreak in West African nations. (U.S. Army Photo by Sgt. 1st Class Brien Vorhees, 55th Signal Company (Combat Camera) / Released)