Impact of drinking water, sanitation and handwashing with soap on childhood diarrhoeal disease

It is somewhat not quite common to have a star-studded paper (meaning that the authors are great names in water and sanitation) – the great names, I’m referring to, are: Jennyfer Wolf, Annette Pruss-Ustun, Jamie Bartram, Sophie Bonjour, Valerie Curtis, Jennifer De France, Lorna Fewtrell, Sandy Cairncross, Thomas Clasen, Oliver Cumming, Richard B. Johnston, Matthew C. Freeman, Bruce Gordon, Paul R. Hunter, P. T. Higgins, and Maria Neira (Director at WHO).

And, it is fantastic to see great authoritative information dished out by these great names. The case in point is the research on impact of WASH (water, sanitation and hygiene) on diarrhoeal diseases. There are, in fact, two papers, with slightly identical topic:

Assessing the impact of drinking water and sanitation on diarrhoeal disease in low- and middle-income settings: systematic review and meta-regression – This is 2014 paper
www.ncbi.nlm.nih.gov/pubmed/24811732

Impact of drinking water, sanitation and handwashing with soap on childhood diarrhoeal disease: updated meta-analysis and meta-regression
This is 2018 paper
www.ncbi.nlm.nih.gov/pubmed/29537671

The abstracts of the 2 papers say it all.

The abstract of 2014 paper says (in part):

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. 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. 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.

The abstract of 2018 paper says (in part):

Safe drinking water, sanitation and hygiene are protective against diarrhoeal disease; a leading cause of child mortality. We undertook a systematic review of articles published between 1970 and February 2016. Study results were combined and analyzed using meta-analysis and meta-regression. A total of 135 studies met the inclusion criteria. Several water, sanitation and hygiene interventions were associated with lower risk of diarrhoeal morbidity. Point-of-use filter interventions with safe storage reduced diarrhoea risk by 61%; piped water to premises of higher quality and continuous availability by 75% and 36% respectively compared to a baseline of unimproved drinking water; sanitation interventions by 25% with evidence for greater reductions when high sanitation coverage is reached; and interventions promoting handwashing with soap by 30% vs. no intervention. Results of the analysis of sanitation and hygiene interventions are sensitive to certain differences in study methods and conditions. Correcting for nonblinding would reduce the associations with diarrhoea to some extent. Although evidence is limited, results suggest that household connections of water supply and higher levels of community coverage for sanitation appear particularly impactful which is in line with targets of the Sustainable Development Goals.

The following are the concrete, established and real-world takeaways from the 2 papers:

• Improvements in drinking water and sanitation are associated with decreased risks of diarrhoea.

• Use of water filters, provision of high-quality piped water and sewer connections, are associated with greater reductions in diarrhoea compared with other interventions.

• 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.

• Water, sanitation and hygiene interventions are associated with lower risk of diarrhoeal morbidity.

• Point-of-use filter interventions with safe storage reduce diarrhoea risk by 61 per cent.

• Piped water to premises of higher quality and continuous availability reduce diarrhoea risk by 75 per cent and 36 per cent respectively, compared to a baseline of unimproved drinking water.

• Sanitation interventions reduce diarrhoea risk by 25 per cent with evidence for greater reductions when high sanitation coverage is reached.

• Interventions promoting handwashing with soap reduce diarrhoea risk by 30 per cent.

• Household connections of water supply and higher levels of community coverage for sanitation appear particularly impactful.


F H Mughal