TABLE 5.

Studies of the impact of water supply on dracunculiasis^a

Country and reference	% Reduction in annual incidenceb	Comment
Ghana (112)	37% reduction for boreholes, deep wells, and dams, compared to ponds, rivers, and shallow wells.	Less risky sources were generally not used exclusively; often they were used only when ponds and pools dried up.
India (133)	78% reduction for village with decreased use of unprotected step wells.	Prevalence in 4 villages increased with proportion of the population using step wells.
India (15)	84% of affected families used pond water, 65% used well water, and 38% used tube wells.	Majority of families using wells and tube wells switched to pond water in summer when improved supplies became more salty and inadequate
India (98)	98% reduction associated with draw well use as opposed to pond use.	93% of those surveyed used pond water sources.
Nigeria (62)	81% reduction in 20 villages provided with boreholes and pumps, along with health education.	Less reduction in villages where boreholes were not convenient or had unpalatable water; no change in control villages.
Nigeria (156)	72% reduction 18 mo after provision of water supply.	Not clear how postprevalence was determined; prevalence higher in those >20 yr old; reductions greater in those <20 yr old.
Uganda (77)	±90% reduction for borehole use in rainy season; ±60% reduction in dry season.	Boreholes, on average, were closer than other sources; exact figures for percent reduction not given.
Sudan (31)	63% reduction for well or borehole use compared to surface sources	Many hand pump users sometimes used other sources because of breakdown, queuing, and inadequate yield.

^aAdapted from reference 65.

^bAll reductions were assessed at least 1 year after intervention.