Monitoring the impact of a national school based deworming programme on soil-transmitted 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 school-age 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. © 2016 the author(s).