Nkombo Island: The Most Important Schistosomiasis mansoni Focus in Rwanda

Abstract

In Rwanda, the initial school-based mapping of schistosomiasis and soil-transmitted helminth (STH) infections was completed in 2008. Despite the classification of low endemicity of intestinal schistosomiasis (Schistosoma mansoni) in Rusizi district, the Neglected Tropical Disease (NTD) programme has received warnings two years after the mapping on high infection level on Nkombo Island located in this district. This study aims to report on prevalence of Schistosoma mansoni infection in an area which was the last to be investigated in Rwanda and provide some critics on current mapping guidelines. The study was done in January 2011 with a sample of 311 schoolchildren aged 10-19 years. Stool screening was performed by Kato-Katz technique. Overall prevalence of S. mansoni was found to be 62.1% (95%CI: 56.4-67.5), ranging from 28.6% (95%CI: 19.2-39.5) to 77.9% (95%CI: 67.0-86.6) across the schools. The prevalence of S. mansoni among the schoolchildren of Nkombo Island was found to be the highest in Rwanda. These findings confirm the extreme focality of schistosomiasis and the fact that the current mapping guidelines are likely to miss some hotspots. For the validation of schistosomiasis distribution at country level, there is need for new innovative mapping methodology that can provide to control programmes more accurate data for planning and undertaking control interventions at the district and the lowest implementation levels. When mapping units have to be designed they should give more priority to areas surrounding perennial water bodies that are considered high-risk zones.