Water supplies for domestic hygiene and community-wide sanitation reduce mortality in childhood

What is it about?

Around 2 million children globally die each year due to preventable causes like diarrhoea and respiratory illness, because they lack improved water, sanitation and hygiene (WASH) amenities, like a toilet at home, a hand washing basin and piped water. Every single one of these deaths is a personal tragedy, affecting all family members. There is great need for rigorous evidence about the impacts of interventions to improve access to and use of WASH amenities on mortality. Precise measurement of effects on mortality is very difficult to do in any single prospective intervention study, like a randomised controlled field trial (RCT). However, multiple existing RCTs are available which provide some data on deaths in childhood. We applied systematic review methods to construct a dataset of 165,000 study participants including 2600 deaths reported in these studies, using meta-analysis to estimate statistically precise intervention effects of water supply, sanitation and hygiene interventions provided to households. We found answers to longstanding questions about how to prevent childhood mortality in low-income contexts in endemic disease circumstances (outside of epidemics like cholera): 1) when people have more water to wash in, they are able to wash properly, which significantly improves the survival chances of their children, reducing deaths in childhood due to any cause by one-third, mainly from diarrhoea, respiratory illness and undernutrition. 2) when sanitation is available to the majority of people in a community, it lessens infection transmission due to children interacting with faeces from open defaecation, halving diarrhoea mortality in childhood. 3) water supply and sanitation improvements can be highly pro-poor investments, having significantly larger effects in communities that are at the lowest rungs of the sanitation ladder and who consequently have the highest pre-intervention mortality rates. 4) we found no effects on mortality of interventions to provide water treatment (e.g. chlorination), or of effects of household WASH improvements on mortality among adults for whom immunity to endemic diseases would be greater.

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Photo by Hasan Almasi on Unsplash

Photo by Hasan Almasi on Unsplash

Why is it important?

Death in childhood accounts for nearly all (99%) of the global respiratory infectious disease burden and 90% of the diarrhoeal disease burden, which are closely related to access to and use of WASH amenities by households. Multiple systematic reviews have been undertaken of the effects of WASH interventions on reported morbidity, but there is a shortage of rigorous evidence on the effects of WASH interventions on mortality. We present the first systematic estimates of the impacts of WASH interventions to households on mortality in childhood. It is an established finding that study participants, while misreporting information like symptoms of a common infection, do not misreport death. This might be because death in childhood is a rare and salient event. A crucial advantage of this approach, therefore, is that mortality is less prone to bias than other reported measures. The findings suggest substantial contributions can be made to reducing the global disease burden in childhood from interventions that improve water supplies to households for domestic hygiene and community-wide sanitation, in places where access is particularly limited, especially in sub-Saharan Africa and parts of South Asia.

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