Surrounded by Ebola patients, a health worker gives thumb ups to visitors near the hot zone. The hot zone is defined by the double barrier orange fence in the event a sick person falls, they cannot contaminate the clean zone. U.S. Agency for International Development is the lead U.S. government organization for Operation United Assistance. U.S. Africa Command is supporting the effort by providing command and control, logistics, training and engineering assets to contain the Ebola virus outbreak in West African nations.