The epidemiology and control of schistosomiasis and soil transmitted helminthes in two communities within the Mwea irrigation scheme in Central Kenya

Abstract

Evidence from recent literature indicates that schistosomiasis remains a major public health problem in developing countries even in the 21st century. Schistosoma mansoni can infect all members of a population but the most vulnerable group with the highest rate of infections is found in children between the ages of 5 and 15 years. Praziquantel is currently the drug of choice for the treatment of all schistosome species occurring in man. The main objective of this study was to investigate the infection and reinfection pattern of Schistosomiasis in school going children after 3 years of therapeutic intervention with praziquantel. Four parasitological surveys were carried out in two pnmary schools in Mwea, an irrigation scheme region in central Kenya after 3 years of mass chemotherapy. Two thousand one hundred and eight pupils aged between five and twenty four years were examined for Schistosoma mansoni infection by Kato thick smear technique. A total of 100 homesteads were sampled on the aspects of risk factors that were believed to play a role in the transmission of schistosomiasis and Soil Transmitted Helminthes (STH). Malacological surveys were also conducted to evaluate the temporal variation in both vector and cercarial densities. The study involved parasitological surveys in two communities with different geographical settings. The study showed that prevalence of infection was 22.7 and 31.1 before treatment, and 6.99 and 8.73 after treatment in Mianya and Mukou respectively. Malacological surveys revealed the presence of 3 species of freshwater snails, namely Biomphalaria pfeifferi, Physca acuta, and Bulinus globossus. The risk factor survey provided qualitative and quantitative data on hygiene and sanitation, water contact and the shoe wearing practice. One of the schools is placed in the Mwea Township (Mukoujwhile the other is placed in the village (Mianya), yet there was no major difference in the transmission, reinfection or water contact patterns. Though the prevalence of soil trab~mitted helminthes is quite low, intestinal Schistosomiasis is still prevalent among the. primary school children in the irrigation scheme even after 3 years of mass chemotherapy. Infection and reinfection of schistosomiasis among the school chi.ldren has therefore been observed even after treatment with praziquantel and the study recommends among other measures non selective mass chemotherapy in the study area.