The Health and Demographic Surveillance System (HDSS) in Niakhar, a rural area of Senegal, is located 135 km east of Dakar. The HDSS was established in 1962 by the Institut de Recherche pour le De´veloppement (IRD) of Senegal to face the shortcomings of the civil registration system and provide demographic indicators. Some 65 villages in the Niakhar area were followed annually by the HDSS from 1962–1969. The study zone was reduced to 8 villages from 1969–1983, and from then on the HDSS was extended to
include 22 other villages, covering a total of 30 villages for a population estimated at 43 000 in January 2012. Thus, 8 villages in the Niakhar area have been under demographic surveillance for almost 50 years and 30 villages for 30 years.