Comparison of the Impact of Different Mass Drug Administration Strategies on Infection with Schistosoma mansoni in Mwanza Region, Tanzania-A Cluster-Randomized Controlled Trial.

Annette Olsen,Safari Kinung’hi,Pascal Magnussen

doi:10.4269/ajtmh.18-0671

Abstract

.Annual school-based mass drug administration with praziquantel has been widely implemented to control schistosomiasis, but other treatment strategies could have a different impact. The aim of this study was to investigate the impact of six different treatment strategies on Schistosoma mansoni infection in a cluster-randomized controlled trial in schoolchildren, in a high transmission area of the Mwanza Region, Tanzania. A total of 150 villages were randomized into six arms with 25 villages in each arm. In each village, approximately 100 schoolchildren aged 9–12 years were randomly selected each year and investigated for S. mansoni prevalence and intensity based on three consecutive stool samples using the duplicate Kato–Katz technique. Four years of community-wide treatment (CWT) was the most intensive treatment strategy, whereas 2 years of school-based treatment (SBT) combined with 2 years without treatment (holiday) was the least intensive treatment. The remaining strategies constituted different combinations of CWT, SBT, and holiday years. Baseline results on S. mansoni infection were obtained from 14,620 schoolchildren from 148 villages, and mean prevalence and mean intensity among infected were 48.6–60.6% and 130.5–229.8 eggs per gram, respectively. Over the years, mean prevalence and mean intensities declined in all arms, but when comparing year 5 mean prevalence and mean intensity, there were no statistically significant differences between treatment arms. Thus, measured in a random selection of schoolchildren aged 9–12 years, four times CWT was not superior to four times SBT, while 2 years of treatment holiday combined with 2 years of SBT had the same impact as 4 years of SBT.

Highlights

Schistosomiasis is caused by trematodes of the genus Schistosoma residing within the blood vessels of the host
Mean prevalence was between 48.6% and 60.6% and individual-level arithmetic mean intensity was between 130.5 and 229.8 epg in the six arms
148.0 75.8 0.024 by 2 years of holiday were compared with 4 years of community-wide treatment (CWT). None of these five comparisons were significantly different. In this cluster-randomized trial, we compared the impact of different treatment strategies on S. mansoni infection among 9- to 12-year-old children attending schools in an area where baseline infection prevalence was 25% or more

Summary

Introduction

Schistosomiasis is caused by trematodes of the genus Schistosoma residing within the blood vessels of the host. The infection is especially widespread in countries of sub-Saharan Africa, and in Tanzania, both the urogenital and intestinal form of schistosomiasis are endemic.[1] In the Mwanza Region bordering Lake Victoria, the intestinal form caused by Schistosoma mansoni is abundant.[2,3]. Mass treatment with praziquantel has for decades been the main strategy for the control of schistosomiasis, and especially, school-based mass drug administration (MDA) has been widely implemented. The aim was to compare the effect of different treatment strategies on S. mansoni and Schistosoma haematobium prevalence and intensity in 9- to 12-year-old schoolchildren over a 5-year period (four treatment rounds) in several different countries.[4] The overall goal of the SCORE project is to provide evidence on how best to gain control of schistosomiasis infections in endemic areas

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