The implications of three major new trials for the effect of water, sanitation and hygiene on childhood diarrhea and stunting: a consensus statement

Abstract

Background: Three large new trials of unprecedented scale and cost, which included novel factorial designs, have found no effect of basic water, sanitation and hygiene (WASH) interventions on childhood stunting, and only mixed effects on childhood diarrhea. Arriving at the inception of the United Nations' Sustainable Development Goals, and the bold new target of safely managed water, sanitation and hygiene for all by 2030, these results warrant the attention of researchers, policy-makers and practitioners. Main body: Here we report the conclusions of an expert meeting convened by the World Health Organization and the Bill and Melinda Gates Foundation to discuss these findings, and present five key consensus messages as a basis for wider discussion and debate in the WASH and nutrition sectors. We judge these trials to have high internal validity, constituting good evidence that these specific interventions had no effect on childhood linear growth, and mixed effects on childhood diarrhea. These results suggest that, in settings such as these, more comprehensive or ambitious WASH interventions may be needed to achieve a major impact on child health. Conclusion: These results are important because such basic interventions are often deployed in low-income rural settings with the expectation of improving child health, although this is rarely the sole justification. Our view is that these three new trials do not show that WASH in general cannot influence child linear growth, but they do demonstrate that these specific interventions had no influence in settings where stunting remains an important public health challenge. We support a call for transformative WASH, in so much as it encapsulates the guiding principle thatin any contexta comprehensive package of WASH interventions is needed that is tailored to address the local exposure landscape and enteric disease burden.

Effects of improved water, sanitation, and hygiene and improved complementary feeding on environmental enteric dysfunction in children in rural Zimbabwe: A cluster-randomized controlled trial

“…We have recently asserted that the elementary WASH interventions implemented in SHINE did not reduce faecal exposure sufficiently to improve growth [46,81]. Our analyses of the EED substudy, and our prior analysis of enteropathogens [76], are both entirely consistent with this conclusion.…”

“…Collectively, the findings from SHINE support our assertion that "transformative WASH" is needed to yield child health gains [81]. Transformative WASH refers to more effective interventions that radically reduce faecal contamination in the household environment [81,91]. These may include a safe and continuous supply of piped household water; high community-wide sanitation coverage; complete separation of animal faeces from the child's environment; and alternative behaviour-change modalities, as we have recently discussed in detail [81,91].…”

“…A better understanding of faecal exposure pathways [86][87][88], places of exposure [89], and patterns of exposure to different enteric pathogens [90] may be important to develop more comprehensive WASH interventions. Collectively, the findings from SHINE support our assertion that "transformative WASH" is needed to yield child health gains [81]. Transformative WASH refers to more effective interventions that radically reduce faecal contamination in the household environment [81,91].…”

“…Transformative WASH refers to more effective interventions that radically reduce faecal contamination in the household environment [81,91]. These may include a safe and continuous supply of piped household water; high community-wide sanitation coverage; complete separation of animal faeces from the child's environment; and alternative behaviour-change modalities, as we have recently discussed in detail [81,91]. Proof-ofconcept trials that evaluate the impact of transformative WASH on biomarkers of EED and on linear growth are still needed to test the hypothesis that EED underlies stunting and can be prevented through effective reductions in faecal-oral transmission.…”

Does Basic Sanitation Prevent Diarrhea? Contextualizing Recent Intervention Trials through a Historical Lens

“…These studies successfully tested specific hypotheses: providing or improving latrines at the household level prevents diarrhea and improves child growth among children in that household. However, as is true for all intervention trials, generalizability of these results to other interventions and settings is limited [5][6][7]. For example, these household-level trials did not test the effect of sanitation at high community coverage, which has been shown to be an important predictor of intervention effectiveness [8][9][10].…”