Tigray is one of the nine (9) administrative regions in Ethiopia. It is comprised of seven zones, of which the Eastern zone is base for the Kiltie Awlaelo Health and Demographic Surveillance Site. The Kiltie Awlaelo HDSS includes 10 kebeles (districts) selected from Eastern zone considering agro climatic, rural/urban and other several other factors to assure representations. Nine of the study districts are rural and only one is from urban. The site is located 802km North of Addis Ababa, the capital of Ethiopia.