objective To estimate the burden of diarrhoeal diseases from exposure to inadequate water, sanitation and hand hygiene in low- and middle-income settings and provide an overview of the impact on other diseases. methods For estimating the impact of water, sanitation and hygiene on diarrhoea, we selected exposure levels with both sufficient global exposure data and a matching exposure-risk relationship. Global exposure data were estimated for the year 2012, and risk estimates were taken from the most recent systematic analyses. We estimated attributable deaths and disability-adjusted life years (DALYs) by country, age and sex for inadequate water, sanitation and hand hygiene separately, and as a cluster of risk factors. Uncertainty estimates were computed on the basis of uncertainty surrounding exposure estimates and relative risks. results In 2012, 502 000 diarrhoea deaths were estimated to be caused by inadequate drinking water and 280 000 deaths by inadequate sanitation. The most likely estimate of disease burden from inadequate hand hygiene amounts to 297 000 deaths. In total, 842 000 diarrhoea deaths are estimated to be caused by this cluster of risk factors, which amounts to 1.5% of the total disease burden and 58% of diarrhoeal diseases. In children under 5 years old, 361 000 deaths could be prevented, representing 5.5% of deaths in that age group. conclusions This estimate confirms the importance of improving water and sanitation in low- and middle-income settings for the prevention of diarrhoeal disease burden. It also underscores the need for better data on exposure and risk reductions that can be achieved with provision of reliable piped water, community sewage with treatment and hand hygiene.

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Burden of disease from inadequate water, sanitation and hygiene in low- and middle-income settings: a retrospective analysis of data from 145 countries

Background: access to safe drinking-water is a fundamental requirement for good health and is also a human right. Global access to safe drinking-water is monitored by WHO and UNICEF using as an indicator “use of an improved source,” which does not account for water quality measurements. Our objectives were to determine whether water from “improved” sources is less likely to contain fecal contamination than “unimproved” sources and to assess the extent to which contamination varies by source type and setting. Methods and findings: studies in Chinese, English, French, Portuguese, and Spanish were identified from online databases, including PubMed and Web of Science, and grey literature. Studies in low- and middle-income countries published between 1990 and August 2013 that assessed drinking-water for the presence of Escherichia coli or thermotolerant coliforms (TTC) were included provided they associated results with a particular source type. In total 319 studies were included, reporting on 96,737 water samples. The odds of contamination within a given study were considerably lower for “improved” sources than “unimproved” sources (odds ratio [OR] = 0.15 [0.10–0.21], I2 = 80.3% [72.9–85.6]). However over a quarter of samples from improved sources contained fecal contamination in 38% of 191 studies. Water sources in low-income countries (OR = 2.37 [1.52–3.71]; p Conclusion: access to an “improved source” provides a measure of sanitary protection but does not ensure water is free of fecal contamination nor is it consistent between source types or settings. International estimates therefore greatly overstate use of safe drinking-water and do not fully reflect disparities in access. An enhanced monitoring strategy would combine indicators of sanitary protection with measures of water quality

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Fecal Contamination of Drinking-Water in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis

Objective: To assess the impact of inadequate water and sanitation on diarrhoeal disease in low- and middle-income settings. Methods: The search strategy used Cochrane Library, MEDLINE & PubMed, Global Health, Embase and BIOSIS supplemented by screening of reference lists from previously published systematic reviews, to identify studies reporting on interventions examining the effect of drinking water and sanitation improvements in low- and middle-income settings published between 1970 and May 2013. Studies including randomised controlled trials, quasi-randomised trials with control group, observational studies using matching techniques and observational studies with a control group where the intervention was well defined were eligible. Risk of bias was assessed using a modified Ottawa-Newcastle scale. Study results were combined using meta-analysis and meta-regression to derive overall and intervention-specific risk estimates. Results: Of 6819 records identified for drinking water, 61 studies met the inclusion criteria, and of 12 515 records identified for sanitation, 11 studies were included. Overall, improvements in drinking water and sanitation were associated with decreased risks of diarrhoea. Specific improvements, such as the use of water filters, provision of high-quality piped water and sewer connections, were associated with greater reductions in diarrhoea compared with other interventions. Conclusions: The results show that inadequate water and sanitation are associated with considerable risks of diarrhoeal disease and that there are notable differences in illness reduction according to the type of improved water and sanitation implemented.

https://www.pseau.org/outils/ouvrages/john_wiley_systematic_review_assessing_the_impact_of_drinking_water_and_sanitation_on_diarrhoeal_disease_in_low_and_middle_income_settings_systematic_review_and_meta_regression_2014.pdf

Assessing the impact of drinking water and sanitation on diarrhoeal disease in low- and middle-income settings: systematic review and meta-regression.

Objectives: To estimate exposure to faecal contamination through drinking water as indicated by levels of Escherichia coli (E. coli) or thermotolerant coliform (TTC) in water sources. Methods: We estimated coverage of different types of drinking water source based on household surveys and censuses using multilevel modelling. Coverage data were combined with water quality studies that assessed E. coli or TTC including those identified by a systematic review (n = 345). Predictive models for the presence and level of contamination of drinking water sources were developed using random effects logistic regression and selected covariates. We assessed sensitivity of estimated exposure to study quality, indicator bacteria and separately considered nationally randomised surveys. Results: We estimate that 1.8 billion people globally use a source of drinking water which suffers from faecal contamination, of these 1.1 billion drink water that is of at least ‘moderate’ risk (>10 E. coli or TTC per 100 ml). Data from nationally randomised studies suggest that 10% of improved sources may be ‘high’ risk, containing at least 100 E. coli or TTC per 100 ml. Drinking water is found to be more often contaminated in rural areas (41%, CI: 31%–51%) than in urban areas (12%, CI: 8–18%), and contamination is most prevalent in Africa (53%, CI: 42%–63%) and South-East Asia (35%, CI: 24%–45%). Estimates were not sensitive to the exclusion of low quality studies or restriction to studies reporting E. coli. Conclusions: Microbial contamination is widespread and affects all water source types, including piped supplies. Global burden of disease estimates may have substantially understated the disease burden associated with inadequate water services. Objectifs: Estimer l'exposition a la contamination fecale par l'eau potable, telle qu'indiquee par les quantites d’Escherichia coli (E. coli) ou de coliformes thermo-tolerants (CTT) dans les sources d'eau. Methodes: Nous avons estime l’etendue de la couverture en differents types de sources d'eau potable a partir d'enquetes sur les menages et des recensements a l'aide de la modelisation a multi-niveaux. Les donnees de couverture ont ete combinees avec des etudes de qualite de l'eau evaluant E. coli ou les CTT y compris celles identifiees par une revue systematique (n = 345). Les modeles predictifs pour la presence et le niveau de contamination des sources d'eau potable ont ete developpes en utilisant la logistique de regression a effets aleatoires et une selection de covariables. Nous avons evalue la sensibilite de l'exposition estimee pour etudier la qualite, les bacteries indicatrices et avons separement considere des etudes nationales randomisees. Resultats: Nous estimons que 1,8 milliard de personnes dans le monde utilisent une source d'eau potable porteuse de contamination fecale. Parmi celles-ci 1,1 milliard boivent de l'eau avec un risque assez «modere» (>10 E. coli ou CTT par 100 ml). Les donnees des etudes nationales randomisees indiquent que 10% des sources ameliorees pourraient etre a risque «eleve», i.e. contenant au moins 100 E. coli ou CTT par 100 ml. L'eau potable se trouve etre plus souvent contaminee dans les zones rurales (41%, IC: 31–51) qu'en milieu urbain (12%, IC: 8–18) et la contamination est la plus repandue en Afrique (53%, CI: 42–63) et en Asie du sud-est (35%, IC: 24–45). Les estimations n’etaient pas affectees par l'exclusion des etudes de faible qualite ou par la restriction aux etudes rapportant sur E. coli. Conclusions: La contamination microbienne est tres repandue et affecte tous les types de sources d'eau, y compris les fournitures par tuyauterie. Les estimations de la charge mondiale des maladies pourraient avoir sensiblement sous-estime la charge de morbidite associee a des services d'eau inadequats. Objetivos: Calcular la exposicion a la contaminacion fecal a traves del agua para consumo, segun los niveles de Escherichia coli (E. coli) o coliformes termotolerantes (CTT) en las fuentes de agua. Metodos: Utilizando modelos multinivel, hemos calculado la cobertura de diferentes tipos de fuentes de agua para consumo basandonos en encuestas a hogares y censos. Los datos de cobertura se combinaron con estudios de calidad del agua que evaluaron niveles de E. coli o CTT, incluyendo aquellos identificados mediante una revision sistematica (n = 345). Los modelos predictivos para la presencia y nivel de contaminacion de las fuentes de agua para consumo se desarrollaron utilizando una regresion logistica de efectos aleatorios y covariables seleccionadas. Evaluamos la sensibilidad de la exposicion calculada segun la calidad del estudio, la bacteria utilizada como indicador y tuvimos en cuenta de forma separada los ensayos nacionales aleatorizados. Resultados: Hemos calculado que 1.8 billones de personas a nivel global utilizan una fuente de agua para beber que sufre de contaminacion fecal; de estas 1.1 billones consumen agua que es al menos de riesgo “moderado” (>10 E. coli o CTT por 100 mL). Datos de estudios nacionales aleatorizados sugieren que un 10% de las fuentes de agua mejoradas pueden ser de‘alto’ riesgo, al contener al menos 100 E. coli o CTT por 100 mL. El agua para consumo se encuentra mas a menudo contaminada en areas rurales (41%, IC: 31–51%) que en areas urbanas (12%, IC: 8–18%) y la contaminacion es mas prevalente en Africa (53%, IC: 42–63%) y el Sudeste Asiatico (35%, CI: 24–45%). Los calculos no eran sensibles a la exclusion de estudios de mala calidad o a la restriccion de estudios en los que se reporta E. coli. Conclusiones: La contaminacion microbiana esta ampliamente extendida y afecta todos los tipos de agua, incluyendo la distribuida a traves de tuberias. Los calculos de la carga global de enfermedad podrian haber subestimado sustancialmente la carga de enfermedad por servicios de agua inadecuados.

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Global assessment of exposure to faecal contamination through drinking water based on a systematic review

Burden of disease from inadequate water, sanitation and hygiene for selected adverse health outcomes: An updated analysis with a focus on low- and middle-income countries.

The Water Safety Plan (WSP) methodology, which aims to enhance safety of drinking water supplies, has been recommended by the World Health Organization since 2004. WSPs are now used worldwide and are legally required in several countries. However, there is limited systematic evidence available demonstrating the effectiveness of WSPs on water quality and health. Iceland was one of the first countries to legislate the use of WSPs, enabling the analysis of more than a decade of data on impact of WSP. The objective was to determine the impact of WSP implementation on regulatory compliance, microbiological water quality, and incidence of clinical cases of diarrhea. Surveillance data on water quality and diarrhea were collected and analyzed. The results show that HPC (heterotrophic plate counts), representing microbiological growth in the water supply system, decreased statistically significant with fewer incidents of HPC exceeding 10 cfu per mL in samples following WSP implementation and noncompliance was also significantly reduced (p < 0.001 in both cases). A significant decrease in incidence of diarrhea was detected where a WSP was implemented, and, furthermore, the results indicate that population where WSP has been implemented is 14% less likely to develop clinical cases of diarrhea.

Gudrun Sigmundsdottir

Papers

Benefits of Water Safety Plans: Microbiology, Compliance, and Public Health