New sub-national water and sanitation maps reveal the deprived populations hidden within national statistics.
Rachel Pullan is a Lecturer at the London School of Hygiene & Tropical Medicine and part of the GAHI team. She writes here about her research into water supply and sanitation across Sub-Saharan Africa, the findings of which are published in PLOS Medicine.
Unsafe drinking water and poor sanitation can have devastating consequences. Together they are responsible for 85% of deaths from diarrhoea and 1% of the global burden of disease. There is now also growing evidence from the NTD sector to support a role for improved water, sanitation and hygiene in reduced risk of intestinal helminth infections.
In 2012, the Millennium Development Goals Report indicated that global targets for halving populations within safe drinking water had been met. But stark differences still exist between regions, and the worldwide targets for sanitation will be missed by half a billion people. In the words of the Water Supply and Sanitation Collaborative Council, we must do better. New post-2015 targets have now been proposed, including ensuring universal access to safe drinking water, sanitation and hygiene (WASH) by 2030. Within this vision is a target to progressively eliminate inequalities in access.
Ensuring safe and adequate water and sanitation is available to everyone remains a major challenge. A key to improvement is knowing where to target resources. It’s well known that large inequalities in WASH exist between countries, especially in Sub-Saharan Africa. In a recent PLOS Medicine article, we demonstrate the huge levels of geographical inequality in water and sanitation that exist within countries.
Revealing this substantial inequality came as something of a surprise. Our original intention when conducting this work was to rapidly generate some data on local context to help improve our predictive maps of worm distributions. A quick look around existing resources soon showed that - although monitoring was occurring at national scales - there was little reliable sub-national data. However, well-conducted population-based national surveys, such as the demographic and health surveys, are available for multiple time points for countries across the continent, providing a wealth of geographical development and health indicators. Using multilevel, spatial models, we decided to model variations in use of improved water and sanitation to predict contemporary coverage across Sub-Saharan Africa at policy relevant scales (usually at the district level).
The resulting maps, and the data underlying them, are now freely available here on the Global Atlas of Helminth Infections. They show the predicted proportion of households using an improved drinking-water source, an improved sanitation facility, and habitually defecating in the open in 2012. By generating these maps, we hope to provide a valuable resource for service delivery providers, policy makers and donors in the WASH sector and beyond.
When looking through the maps, it’s clear that there are deprived areas within nearly all Sub-Saharan countries where substantially more of the resident population have to use unsafe drinking water sources and/or poor sanitation. For example, comparing districts with the lowest coverage to those with the best reveals a 1.5–8 fold difference in use of improved drinking water within countries, a 2–18 fold difference in use of improved sanitation within countries, and a 2–80 fold difference in levels of open defecation within countries. There are clearly many countries struggling to target resources to areas of greatest need.
The implications of geographical inequalities in water and sanitation coverage go beyond considerations of effective service provision. Being able to identify where inequalities exist will not only bring us closer to the goal of universal water and sanitation - a fundamental human right - but can also provide insight into the epidemiology and control of many infectious diseases, including NTDs. For example, these maps can be used to identify areas where water and sanitation coverage remains low, and so where drug-based interventions alone are unlikely to eliminate or control STH and schistosomiasis.
It has been argued that an historic dissociation of WASH and health sectors has led to major problems in developing and maintaining essential infrastructure. However, there is now a growing resolve for collaboration and coordination between the two sectors, and we hope these maps will contribute to this dialogue. We must now work together to develop common cross-sectoral coverage and impact indicators, coordinated intervention strategies and investment plans to reduce inequality and marginalization and improve health and wellbeing in the world’s poorest countries.
This work forms one of the bases of a new area of research interest for us at GAHI - gaining a better understanding of the context of NTD control. We realise that achieving sustained control and eventual elimination of these worms is not simply a case of targeting drug treatments to those areas where the infections are prevalent. It is also important that we understand how contextual factors, including use of safe, improved water supply and sanitation facilities, can impact upon the effectiveness of treatment.
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