Effects of water, sanitation, handwashing and nutritional interventions on soil-transmitted helminth infections in young children: A cluster-randomized controlled trial in rural Bangladesh.

Ayse Ercumen,John M Colford,Audrie Lin,Rashidul Haque,Zahidur Rahman,Alan E Hubbard,Leanne Unicomb,Christine Stewart,Jade Benjamin-Chung,Stephen P Luby,Mahbubur Rahman,Sarker Masud Parvez,Benjamin F Arnold,Susana Vaz Nery

doi:10.1371/journal.pntd.0007323

Abstract

BackgroundSoil transmitted helminths (STH) infect >1.5 billion people. Mass drug administration (MDA) effectively reduces infection; however, there is evidence for rapid reinfection and risk of potential drug resistance. We conducted a randomized controlled trial in Bangladesh (WASH Benefits, NCT01590095) to assess whether water, sanitation, hygiene and nutrition interventions, alone and combined, reduce STH in a setting with ongoing MDA.Methodology/Principal findingsIn 2012–2013, we randomized 720 clusters of 5551 pregnant women into water treatment, sanitation, handwashing, combined water+sanitation+handwashing (WSH), nutrition, nutrition+WSH (N+WSH) or control arms. In 2015–2016, we enrolled 7795 children, aged 2–12 years, of 4102 available women for STH follow-up and collected stool from 7187. We enumerated STH infections with Kato-Katz. We estimated intention-to-treat intervention effects on infection prevalence and intensity. Participants and field staff were not blinded; laboratory technicians and data analysts were blinded.Prevalence among controls was 36.8% for A. lumbricoides, 9.2% for hookworm and 7.5% for T. trichiura. Most infections were low-intensity. Compared to controls, the water intervention reduced hookworm by 31% (prevalence ratio [PR] = 0.69 (0.50,0.95), prevalence difference [PD] = -2.83 (-5.16,-0.50)) but did not affect other STH. Sanitation improvements reduced T. trichiura by 29% (PR = 0.71 (0.52,0.98), PD = -2.17 (-4.03,-0.38)), had a similar borderline effect on hookworm and no effect on A. lumbricoides. Handwashing and nutrition interventions did not reduce any STH. WSH and N+WSH reduced hookworm prevalence by 29–33% (WSH: PR = 0.71 (0.52,0.99), PD = -2.63 (-4.95,-0.31); N+WSH: PR = 0.67 (0.50,0.91), PD = -3.00 (-5.14,-0.85)) and marginally reduced A. lumbricoides. Effects on infection intensity were similar.Conclusions/SignificanceIn a low-intensity infection setting with MDA, we found modest but sustained hookworm reduction from water treatment and combined WSH interventions. Impacts were more pronounced on STH species with short vs. long-term environmental survival. Our findings suggest possible waterborne transmission for hookworm. Water treatment and sanitation improvements can augment MDA to interrupt STH transmission.Trial registrationNCT01590095.

Highlights

Over 1.5 billion people globally are infected with soil transmitted helminths (STH), 819 million with Ascaris lumbricoides, 465 million with Trichuris trichiura, and 439 million with Necator americanus and Ancylostoma duodenale [1,2]
2.5 years after the initiation of interventions, we found reductions in Soil transmitted helminths (STH) infection from water treatment and sanitation interventions; there was no reduction from the handwashing and nutrition interventions
The prevalence of protozoan parasites measured among children aged 18– 27 months at baseline was balanced between arms [31]

Summary

Introduction

Over 1.5 billion people globally are infected with soil transmitted helminths (STH), 819 million with Ascaris lumbricoides (roundworm), 465 million with Trichuris trichiura (whipworm), and 439 million with Necator americanus and Ancylostoma duodenale (hookworms) [1,2]. Sanitation, handwashing & nutrition on STH: A randomized controlled trial chemotherapy is the cornerstone of global WHO policy for STH control and effectively reduces infection [3]. Without environmental interventions to interrupt transmission, rapid reinfection is common; a systematic review demonstrated that prevalence reverts to 94% of pre-treatment levels for A. lumbricoides, 82% for T. trichiura and 57% for hookworm within 12 months post-treatment [5]. Sanitation and hygiene improvements could potentially complement MDA programs in reducing STH transmission [6]. Mass drug administration (MDA) effectively reduces infection; there is evidence for rapid reinfection and risk of potential drug resistance. We conducted a randomized controlled trial in Bangladesh (WASH Benefits, NCT01590095) to assess whether water, sanitation, hygiene and nutrition interventions, alone and combined, reduce STH in a setting with ongoing MDA

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