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Infections with enteric pathogens impose a heavy disease burden, especially among young children in low-income countries. Recent findings from randomized controlled trials of water, sanitation, and hygiene interventions have raised questions about current methods for assessing environmental exposure to enteric pathogens. Approaches for estimating sources and doses of exposure suffer from a number of shortcomings, including reliance on imperfect indicators of fecal contamination instead of actual pathogens and estimating exposure indirectly from imprecise measurements of pathogens in the environment and human interaction therewith. These shortcomings limit the potential for effective surveillance of exposures, identification of important sources and modes of transmission, and evaluation of the effectiveness of interventions. In this review, we summarize current and emerging approaches used to characterize enteric pathogen hazards in different environmental media as well as human interaction with those media (external measures of exposure), and review methods that measure human infection with enteric pathogens as a proxy for past exposure (internal measures of exposure). We draw from lessons learned in other areas of environmental health to highlight how external and internal measures of exposure can be used to more comprehensively assess exposure. We conclude by recommending strategies for advancing enteric pathogen exposure assessments.

BackgroundThree 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 bodyHere 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.ConclusionThese 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 that - in any context - a comprehensive package of WASH interventions is needed that is tailored to address the local exposure landscape and enteric disease burden.

Do self-help groups (SHGs), village-based associations designed to encourage savings, household production and social cohesion among the poor, meet their goals? We examine economic outcomes and the pro-social behavior of 540 households in a randomized control trial (RCT) of a SHG program (randomized at the commune level) in rural Siem Reap, Cambodia using survey data and a rich set of economic and social capital indicators. We measured social capital—defined as social norms and the social networks that support them—with household and network surveys and lab activities that gauge altruism, trust, trustworthiness and the willingness to contribute to public goods. We find that the program successfully increased participation in SHGs and strengthened SHG-related networks. As intended the program significantly increased the number of households with non-zero savings as well as savings levels and it led to a noticeable shift in household production towards livestock. We cannot document increases in household incomes, assets or expenditure. There were also no sizeable wider effects on social capital and networks other than those related to SHGs directly, although we cannot statistically rule out small positive effects in the case of some social capital indicators. In addition to these empirical findings the study provides an example of innovative program evaluation techniques that employed a field experiment, lab-in-the-field behavioral measures, network measures as well as traditional survey measures. [ABSTRACT FROM AUTHOR]