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BANDAFASSI DEMOGRAPHIC SURVEILLANCE SYSTEM SENEGAL INSTITUT NATIONAL D’ÉTUDES DÉMOGRAPHIQUES PARIS PROGRAMME NATIONAL DE LUTTE CONTRE LE SIDA DAKAR CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE/MUSÉUM NATIONAL D’HISTOIRE NATURELLE PARIS UNIVERSITÉ CHEIKH ANTA DIOP/INSTITUT DE RECHERCHE POUR LE DÉVELOPPEMENT DAKAR SS EE NN EE GG AA LL SenegalSenegal SS EE NN EE GG AA LL TambacoundaTambacounda RegionRegion TambacuondaTambacuonda RegionRegion GambiaGambia GambiaGambia RegionRegion BBaannddaafffaassssiii DDSSSS AArrreeaa KedougouKedougou DepartmentDepartment 00 5050 100100 00 100100 200200 KilometersKilometers KilometersKilometers KilometersKilometers LOCATION OF BANDAFASSI DSS SITE, SENEGAL: 10,500 under surveillance. Gilles Pison, Emmanuelle Guyavarch, Abdoulaye Wade, Alexis Gabadinho, Catherine Enel, and Cheikh Sokhna Chapter C18 Page 1 INDEPTH Monograph: Volume 1 Part C Bandafassi Demographic Surveillance System, Senegal 1. BANDAFASSI DSS SITE DESCRIPTION 1.1 Physical Geography of the DSS Areas The Bandafassi area is located in Senegal, between 12°46’ and 12°30’ north latitutude and between 12°16’ and 12°31’ east longitude, with altitude ranging from 60 to 426 meters above mean sea level. It is located in the Region of Tambacounda, in the Département of Kedougou, in Eastern Senegal, near the boarder between Senegal, Mali and Guinea. It corresponds to about half the Arrondissement of Bandafassi. The Bandafassi area is about 25 km long by 25 km large and total 600 sq km. It belongs to the Sudan savanna ecological zone. The climate is characterized by two seasons, a rainy season, from June to October, and a dry season, from November to May, with average rainfall of 1,097 mm per year during the period 1984-1995. The Bandafassi area is about 500 km distant from the capital Dakar. 1.2 Population Characteristics of the Bandafassi DSS Area The Bandafassi area had a population of 10,509 inhabitants on 1st January 2000 and population density was low: about 18 inhabitants per square kilometer. It has 42 villages. The villages are small (240 inhabitants on average) and some are divided in hamlets. The population of the area is comprised of three ethnic groups who live in distinct villages. In order of settlement in the area, these are: • The Bedik (25% of the population). This ethnic group, which was probably more extended in the past, has its own language, related to the Mande linguistic group. • The Mandinka (16% of the population). They are part of the Mandinka people widespread in the Western part of West Africa. • The Fula Bande (59% of the population). They are part of the Fula of West Africa and very close culturally to the sub-group of Guinea. The Fula and a minority of the Mandinka are Moslems, while the majority of the Mandinka and the Bedik are animists, with a few christians among these two groups. The area is rural, the main activities being cultivation of cereals (sorghum, maize, rice), peanuts and cotton, and cattle breeding. One part of the young male population engages each year in seasonal migrations to cities or other rural areas of the country. There were primary schools in 10 villages in 2000, with 7 of them having only 1 teacher each. Secondary schools were in the cities of Kedougou (at a distance of 25 km on average) or Tambacounda (250 km). In 2000, 26% of adult women aged 15–29 years had been to school (for at least one year), and 10% of those aged 30-44 years. The residential unit is a compound housing the members (15 on average) of an extended patrilineal family. Usually, a compound contains one hut for each ever-married woman and sometimes additional huts for unmarried adult sons and/or for the head of the compound. Polygyny is frequent: there are 180 married women for 100 married men. When a man has several wives, each one has her own hut close to the others. Children sleep in their mother's hut until about age 15. Teen-age girls leave the compound to marry, and boys build small huts to sleep in, often with age-mates. Chapter C18 Page 2 INDEPTH Monograph: Volume 1 Part C Bandafassi Demographic Surveillance System, Senegal Older children may sleep in the huts of old or childless women, even if their mother lives in her own hut in the compound (Pison, 1982). The vast majority of dwellings are huts covered with thatched roofs. Water is taken from river, backwater, wells or bore holes. Most of the compounds have no toilet facilities. There is no electricity. The area is one of the remotest in Senegal: distances to the main centers of the country are large (700 km from the capital of the country, Dakar, 250 km from the capital of the region, Tambacounda) and local roads are bad, often impracticable during the rainy season which lasts half of the year. The closest hospital where delivering women who need a cesarian section can be operated is at Tambacounda. There is one unique public health post within the area, located in the village of Bandafassi, and run by a public nurse. For vaccinations, the area is divided into two different sectors, depending on different health services. The southern sector is covered by the public health post of Bandafassi where children are vaccinated, but the nurse also travels around by motor bike to vaccinate children in more remote villages. In the northern sector of the area, the Catholic mission in Kedougou sends a nurse to each village several times a year, to vaccinate and examine children and mothers. Vaccination coverage rate was nearly zero before 1987. The national immunization program (EPI) reached the area for the first time in 1987. In 1992, 39% of children aged 12-35 months were fully vaccinated. 2. BANDAFASSI DSS PROCEDURES 2.1 Introduction to the Bandafassi DSS The original objective of the Bandafassi project in 1970 was to measure survival rates in different subgroups of a population defined by their genotypes (for example, comparing persons with the gene responsible for drepanocytosis (gene S) and those who did not have this gene). Genotypes had to be determined from blood samples, and survival rates estimated from the follow-up of persons with known genotype during several years. It was decided to follow the whole population of the Bandafassi area and to collect demographic information on births, deaths, marriages and migrations regularly. The genetic objective was rapidly abandoned and the project became a demographic and health project whose main objective was to study the demographic and health situation of a west African population with very high mortality levels, to observe changes over time and examine the factors involved (Pison et al., 1997). The baseline survey was organised at different dates in the different sub-populations of the Bandafassi area: in 1970 for the Mandinka villages (1,095 inhabitants at that time), in 1975 for the Fula villages (3,701 inhabitants) and in 1980 for the Bedik villages (1,818 inhabitants). In 1975 and 1980, as mentioned above, the newly censused sub-population was added to the population yet followed up. The total population, which was 6,577 inhabitants on 1/1/1980, has increased to 10,509 inhabitants on 1/1/2000. The Bandafassi studies are managed by a team of researchers from several institutions based in Senegal and in France. Several doctoral students from Senegal and France are also working in the project. In France, the main institution involved is the “Institut national d’études démographiques”, in Paris, in particular, the “Unité Population et développement”, with collaboration with the “Unité Dynamique et santé des populations humaines” from the “Centre national de la recherche scientifique” and the “Muséum national d’histoire naturelle”. In Senegal, the institutions involved are the “Unité de paludologie afro-tropicale” from the “Institut de recherche pour le Chapter C18 Page 3 INDEPTH Monograph: Volume 1 Part C Bandafassi Demographic Surveillance System, Senegal développement”, the “Programme national de lutte contre le sida” of Ministry of Health, and the Cheikh Anta Diop University (University of Dakar), whose several students work in the project. 2.2 Bandafassi DSS Data Collection and Processing 2.2.1 Field Procedures a) Initial census The initial census was very similar in the different sub-populations of Bandafassi and in Mlomp. It consisted of a census and of several surveys which were organised just after it to improve the information of the census and collect other data necessary for subsequent studies. These included an age survey, to estimate or improve the ages of adults and children collected by the census, which were unreliable for most, especially in Bandafassi. We used an indirect method based on the classification of the population of a village by birth rank (Pison, 1980). It also included a genealogical survey, to collect genealogies going up to known ascendants and then down to living collateral relatives. One use of the genealogies in the project is to get a detailed information on the relationships between the members of a compound and in particular the relationship of each one with the head of the compound (Pison, 1985). Finally there was a union and birth histories survey for adult men and women. This was achieved totally in Mlomp, but only partially in Bandafassi. At the census, a person has been considered as a member of the compound if the head of the compound declared her as such. This definition was broad and results in a de jure population under study. Thereafter, a criterion was used to decide whether a person was to be excluded, or included, in the population, and when. A person exits from the study population either by death or emigration. As part of the population of Bandafassi engages in seasonal migrations, with seasonal migrants sometimes remaining one or two years outside the area before coming back, we decided that a person who was absent at three successive yearly rounds without returning in between had emigrated and was no longer resident in the study population at the date of the third round.