Sustaining Control of Schistosomiasis Mansoni in Western Côte d'Ivoire: Results from a SCORE Study, One Year after Initial Praziquantel Administration.

Rufin K Assaré,Jürg Utzinger,Stefanie Knopp,Mamadou Ouattara,Patrick K Yao,Nicaise A N’Guessan,Eliézer K N’Goran,Yves-Nathan T Tian-Bi,Jean T Coulibaly,Aboulaye Meïté,Ahoua Yapi,Eveline Hürlimann,Jeffrey Michael Bethony

doi:10.1371/journal.pntd.0004329

Abstract

BackgroundThe Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) has launched several large-scale trials to determine the best strategies for gaining and sustaining control of schistosomiasis and transitioning toward elimination. In Côte d’Ivoire, a 5-year cluster-randomized trial is being implemented in 75 schools to sustain the control of schistosomiasis mansoni. We report Schistosoma mansoni infection levels in children one year after the initial school-based treatment (SBT) with praziquantel and compare with baseline results to determine the effect of the intervention.MethodologyThe baseline cross-sectional survey was conducted in late 2011/early 2012 and the first follow-up in May 2013. Three consecutive stool samples were collected from 9- to 12-year-old children in 75 schools at baseline and 50 schools at follow-up. Stool samples were subjected to duplicate Kato-Katz thick smears. Directly observed treatment (DOT) coverage of the SBT was assessed and the prevalence and intensity of S. mansoni infection compared between baseline and follow-up.Principal FindingsThe S. mansoni prevalence in the 75 schools surveyed at baseline was 22.1% (95% confidence interval (CI): 19.5–24.4%). The DOT coverage was 84.2%. In the 50 schools surveyed at baseline and one year after treatment, the overall prevalence of S. mansoni infection decreased significantly from 19.7% (95% CI: 18.5–20.8%) to 12.8% (95% CI: 11.9–13.8%), while the arithmetic mean S. mansoni eggs per gram of stool (EPG) among infected children slightly increased from 92.2 EPG (95% CI: 79.2–105.3 EPG) to 109.3 EPG (95% CI: 82.7–135.9 EPG). In two of the 50 schools, the prevalence increased significantly, despite a DOT coverage of >75%.Conclusions/SignificanceOne year after the initial SBT, the S. mansoni prevalence had decreased. Despite this positive trend, an increase was observed in some schools. Moreover, the infection intensity among S. mansoni-infected children was slightly higher at the 1-year follow-up compared to the baseline situation. Our results emphasize the heterogeneity of transmission dynamics and provide a benchmark for the future yearly follow-up surveys of this multi-year SCORE intervention study.

Highlights

Schistosomiasis is a neglected tropical disease that exerts a considerable public health problem in 78 tropical and subtropical countries [1]
Schistosomiasis is a parasitic worm disease that is widespread in sub-Saharan Africa
To better understand how to gain and sustain the control of schistosomiasis and how to eliminate this disease in different epidemiologic settings, the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) has launched several multi-year studies that are being implemented in East and West Africa

Summary

Introduction

Schistosomiasis is a neglected tropical disease that exerts a considerable public health problem in 78 tropical and subtropical countries [1]. According to WHO, in areas with high schistosomiasis endemicity (prevalence 50%), all school-aged children and adult people at risk of infection should be treated annually [10]. Two 5-year cluster-randomized trials are being implemented in Côte d’Ivoire and Kenya [14,15] These trials are school-based with three treatment arms (25 schools per arm) and aim to assess whether annual school-based treatment (SBT) with praziquantel for four years (arm A), annual SBT in years 1 and 2, followed by “drug holidays” in years 3 and 4 (arm B), or SBT in years 1 and 3, spaced by“drug holidays” in years 2 and 4 (arm C) will substantially reduce the prevalence and intensity of Schistosoma infection and keep infection at low levels. In Côte d’Ivoire, a 5-year cluster-randomized trial is being implemented in 75 schools to sustain the control of schistosomiasis mansoni. We report Schistosoma mansoni infection levels in children one year after the initial school-based treatment (SBT) with praziquantel and compare with baseline results to determine the effect of the intervention

Methods

Results

Discussion

Conclusion