Water supply and Dracunculus medinensis in Africa
thesisposted on 20.10.2010, 13:33 by Robert W. Larsson
The thesis examines control and eradication of Guinea worm in West Africa and investigates factors, especially water supply, related to the incidence of Guinea worm. The study was carried out in North Zou, Benin between 1987 and 1990 and in Nigeria between 1989 and 1993 during water supply and Guinea worm eradication programme execution. About 5% of villages in Nigeria, located in one half the LGAs were infected. The number of annual cases in a region was related to the previous year's cases, although 5-10% of the regions changed between infected and non-infected. Cases were not statically focused in villages. The relative risk of infection in a village based on the previous year's infection was 1.74 in North Zou. Incidence varied inversely and endemicity varied directly with village population. Villages of all sizes were infected. Prevalence varies seasonally by region. Incidence was low at high altitudes, in sandy and alluvial soils, in areas with high or low annual rainfall and in densely populated areas. Incidence was not otherwise related to rainfall, vegetation, altitude, soils, geology or distance to rivers. Incidence among Muslims and Christians was the same but varied by ethnic group. Incidence in an area was strongly related to the ratio of females to males. School attendance in endemic areas fell during the transmission period. Losses in Nigeria in 1990/91 were £16 million. Provision of improved water supply lowered incidence by 50%. Endemicity was 20% lower in villages in North Zou with water supply but endemicity did not fall immediately following provision and a difference was not seen in Nigeria. Water supply to all infected villages in Nigeria identified in 1990/91 would cost £23 million. Three possible water supply strategies were examined. Ten water supply options were considered and roof rainwater catchment was found the most promising. Factors that reduce the effective use of water supply were examined. Water supply coverage in endemic countries is 27%. The countries are among the poorest and least developed in the world. The lack of static focus of cases in villages, the low impact of water supply, and the difficulty of supplying water to all endemic areas make Guinea worm eradication by 1999 unlikely.
- Social Sciences
- Geography and Environment