Monitoring the impact of a national school based deworming programme on soiltransmitted helminths in Kenya: the first three years, 2012 - 2014.

Background: In 2012, the Kenyan Ministries of Health and of Education began a programme to deworm all schoolage children living in areas at high risk of soil-transmitted helminths (STH) and schistosome infections. The impact of this school-based mass drug administration (MDA) programme in Kenya is monitored by the Kenya Medical Research Institute (KEMRI) as part of a five-year (2012-2017) study. This article focuses on the impact of MDA on STH infections and presents the overall achieved reductions from baseline to mid-term, as well as yearly patterns of reductions and subsequent re-infections per school community. Methods: The study involved a series of pre- and post-intervention, repeat cross-sectional surveys in a representative, stratified, two-stage sample of schools across Kenya. The programme contained two tiers of monitoring; a national baseline and mid-term survey including 200 schools, and surveys conducted among 60 schools pre- and post-intervention. Stool samples were collected from randomly selected school children and tested for helminth infections using Kato-Katz technique. The prevalence and mean intensity of each helminth species were calculated at the school and county levels and 95% confidence intervals (CIs) were obtained by binomial and negative binomial regression, respectively, taking into account clustering by schools. Results: The overall prevalence of STH infection at baseline was 32.3% (hookworms: 15.4%; Ascaris lumbricoides: 18.1%; and Trichuris trichiura: 6.7%). After two rounds of MDA, the overall prevalence of STH had reduced to 16. 4% (hookworms: 2.3%; A. lumbricoides: 11.9%; and T. trichiura: 4.5%). The relative reductions of moderate to heavy intensity of infections were 33.7% (STH combined), 77.3% (hookworms) and 33.9% (A. lumbricoides). For T. trichiura, however, moderate to heavy intensity of infections increased non-significantly by 18.0% from baseline to mid-term survey. Conclusion: The school-based deworming programme has substantially reduced STH infections, but because of ongoing transmission additional strategies may be required to achieve a sustained interruption of transmission. [ABSTRACT FROM AUTHOR]