Lorna Fewtrell

Water, sanitation, and hygiene interventions to reduce diarrhoea in less developed countries: a systematic review and meta-analysis

Many studies have reported the results of interventions to reduce illness through improvements in drinking water, sanitation facilities, and hygiene practices in less developed countries. There has, however, been no formal systematic review and meta-analysis comparing the evidence of the relative effectiveness of these interventions. We developed a comprehensive search strategy designed to identify all peer-reviewed articles, in any language, that presented water, sanitation, or hygiene interventions. We examined only those articles with specific measurement of diarrhoea morbidity as a health outcome in non-outbreak conditions. We screened the titles and, where necessary, the abstracts of 2120 publications. 46 studies were judged to contain relevant evidence and were reviewed in detail. Data were extracted from these studies and pooled by meta-analysis to provide summary estimates of the effectiveness of each type of intervention. All of the interventions studied were found to reduce significantly the risks of diarrhoeal illness. Most of the interventions had a similar degree of impact on diarrhoeal illness, with the relative risk estimates from the overall meta-analyses ranging between 0.63 and 0.75. The results generally agree with those from previous reviews, but water quality interventions (point-of-use water treatment) were found to be more effective than previously thought, and multiple interventions (consisting of combined water, sanitation, and hygiene measures) were not more effective than interventions with a single focus. There is some evidence of publication bias in the findings from the hygiene and water treatment interventions.

Estimating the Burden of Disease from Water, Sanitation, and Hygiene at a Global Level

We estimated the disease burden from water, sanitation, and hygiene at the global level taking into account various disease outcomes, principally diarrheal diseases. The disability-adjusted life year (DALY) combines the burden from death and disability in a single index and permits the comparison of the burden from water, sanitation, and hygiene with the burden from other risk factors or diseases. We divided the worlds population into typical exposure scenarios for 14 geographical regions. We then matched these scenarios with relative risk information obtained mainly from intervention studies. We estimated the disease burden from water, sanitation, and hygiene to be 4.0% of all deaths and 5.7% of the total disease burden (in DALYs) occurring worldwide, taking into account diarrheal diseases, schistosomiasis, trachoma, ascariasis, trichuriasis, and hookworm disease. Because we based these estimates mainly on intervention studies, this burden is largely preventable. Other water- and sanitation-related diseases remain to be evaluated. This preliminary estimation of the global disease burden caused by water, sanitation, and hygiene provides a basic model that could be further refined for national or regional assessments. This significant and avoidable burden suggests that it should be a priority for public health policy.

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

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.

Drinking-water nitrate, methemoglobinemia, and global burden of disease: a discussion.

On behalf of the World Health Organization (WHO), I have undertaken a series of literature-based investigations examining the global burden of disease related to a number of environmental risk factors associated with drinking water. In this article I outline the investigation of drinking-water nitrate concentration and methemoglobinemia. The exposure assessment was based on levels of nitrate in drinking water greater than the WHO guideline value of 50 mg/L. No exposure–response relationship, however, could be identified that related drinking-water nitrate level to methemoglobinemia. Indeed, although it has previously been accepted that consumption of drinking water high in nitrates causes methemoglobinemia in infants, it appears now that nitrate may be one of a number of co-factors that play a sometimes complex role in causing the disease. I conclude that, given the apparently low incidence of possible water-related methemoglobinemia, the complex nature of the role of nitrates, and that of individual behavior, it is currently inappropriate to attempt to link illness rates with drinking-water nitrate levels.

Water Quality: Guidelines, Standards and Health: Assessment of Risk and Risk Management for Water-Related Infectious Disease

The quality of water, whether it is used for drinking, irrigation or recreational purposes, is significant for health in both developing and developed countries worldwide. In responding to this challenge, countries develop standards intended to protect public health. Recognising this, the World Health Organization (WHO) develops ‘guidelines’ that present an authoritative assessment of the health risks associated with hazards through water and of the effectiveness of approaches to their control. To date, the various WHO guidelines concerned with water ( Guidelines for drinking-water quality; Guidelines for the safe use of wastewater and excreta in agriculture and aquaculture; Guidelines for safe recreational water environments ) have been developed in isolation from one another. However, their common primary concern is for health hazards derived from excreta. Addressing their specific areas of concern together will tend to support better health protection and highlight the value of interventions closer to sources of pollution, which may otherwise be under-valued. The potential to increase consistency in approaches to assessment and management of water-related microbial hazards was discussed by an international group of experts between 1999 and 2001. These discussions led to the development of a harmonised framework, which was intended to inform the process of development of guidelines and standards. Subsequently, a series of reviews was developed and refined, which addressed the principle issues of concern linking water and health to the establishment and implementation of effective, affordable and efficient guidelines and standards. The book is based on these reviews and the harmonised framework. This book will prove invaluable to all those concerned with issues relating to microbial water quality and health, including environmental and public health scientists, water scientists, policy makers and those responsible for developing standards and regulations. This title belongs to WHO Water Series . ISBN: 9781780405889 (eBook) ISBN: 9781900222280 (Print)

Assessing Microbial Safety of Drinking Water: Improving Approaches and Methods

Inadequate drinking water quality and poor sanitation have remained the worlds major causes of preventable morbidity and mortality. In 1996 the OECD called for concerted action to improve the assessment and management of the worlds sources of drinking water. This guidance document seeks to respond to this call. It is the product of a shared initiative between the OECD and the World Health Organization. It is a state-of-the-art review that will contribute to the revisions of the WHOs Guidelines for Drinking Water Quality. Assessing Microbial Safety Of Drinking-water has elements of both revolution and evolution. It is revolutionary in that it supports a rapidly emerging approach for a broader, system-wide management perspective. This is based on a risk management framework that has evolved from the traditional indicator concept to include multiple parameters and where consideration is also given to tolerable risk, water quality targets and public health status. This title belongs to WHO Drinking-water Quality Series. . ISBN: 9781780405872 (eBook) ISBN: 9781843390367 (Print)

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

To assess the impact of inadequate water and sanitation on diarrhoeal disease in low‐ and middle‐income settings.

Hygiene and health: systematic review of handwashing practices worldwide and update of health effects.

To estimate the global prevalence of handwashing with soap and derive a pooled estimate of the effect of hygiene on diarrhoeal diseases, based on a systematic search of the literature.

Faecal indicator organism concentrations and catchment export coefficients in the UK.

Characterisation of faecal indicator organism (FIO) concentrations and export coefficients for catchments with particular combinations of land use and under specific climatic regimes is critical in developing models to predict daily loads and apportion sources of the microbial parameters used to regulate water quality. Accordingly, this paper presents a synthesis of FIO concentration and export coefficient data for the summer bathing season, with some comparative winter data, for 205 river/stream sampling points widely distributed across mainland UK. In terms of both geometric mean (GM) FIO concentrations and export coefficients (expressed as cfu km(-2) h(-1)), the results reveal (1) statistically significant elevations at high flow compared with base flow, with concentrations typically increasing by more than an order of magnitude and export coefficients by about two orders; (2) significantly higher values in summer than in winter under high-flow conditions; and (3) extremely wide variability between the catchments (e.g. four orders of magnitude range for GM faecal coliform concentrations), which closely reflects land use-with urban areas and improved pastures identified as key FIO sources. Generally, these two most polluting land uses are concentrated in lowland areas where runoff (m3 km(-2) h(-1)) is low compared with upland areas, which in the UK are dominated by rough grazing and forestry. Consequently, contrasts in export coefficients between land use types are less than for FIO concentrations. The GMs reported for most land use categories are based on 13 sites and exhibit quite narrow confidence intervals. They may therefore be applied with some confidence to other catchments in the UK and similar geographical regions elsewhere. Examples are presented to illustrate how the results can be used to estimate daily summer base- and high-flow FIO loads for catchments with different land use types, and to assess the likely effectiveness of certain strategies for reducing FIO pollutant loadings in areas with extensive areas of lowland improved pasture.

An attempt to quantify the health impacts of flooding in the UK using an urban case study.

OBJECTIVES To quantify, so far as possible, the health effects of flooding in the UK to allow comparison between different flooding events. METHODS The health effects resulting from flooding events were determined through an extensive literature search, where information existed to enable the quantification of these effects. Disability-adjusted life years (DALYs) were used to enable the comparison between different health impacts and different flood events and populations, using two sites subject to pluvial flooding in the Bradford area, UK. RESULTS Relatively few properties (and hence people) were affected by flooding in the case study areas and there were no predicted deaths or serious injuries; these results were supported by anecdotal knowledge of the events. Mental health problems, characterized as psychological distress, were estimated for adults; these were found to dominate the calculated health impacts, being considerably greater than the combined physical symptoms in the case study examples. CONCLUSIONS While it was not possible to quantify every flood-related health impact, this method does allow comparisons to be made between different flood events and mitigation strategies.