JUBA, Oct. 7 (Xinhua) -- South Sudan has stepped up nationwide preparedness and surveillance against Ebola disease caused by the Bundibugyo virus after neighboring Kenya confirmed an imported case, the Ministry of Health said on Wednesday. No cases have been detected in the country and the health system has been placed on high alert, according to the ministry. The ministry said this heightened posture is a proactive response to increased regional mobility and vital trade corridors linking South