Sanitation and health evidence: request for input to achieve consensus

  • sayboom
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Sanitation and health evidence: request for input into a consensus meeting


Following the publication of results from a number of recent studies investigating links between improvements in sanitation and health (such as the WaSHBenefits study, studies in Tamil Nadu, Madya Pradesh and Orissa in India and others) some of you have contacted us with questions and concerns about the seeming lack of consensus about the relationship between sanitation and health demonstrated in those studies.

Looking at a number of historical studies, it is hard to imagine that improvements in sanitation did not play a significant role in improving population health. And indeed, older as well as more recent historical evidence from US, Europe and developing countries establish causal relationships between sanitation and health. However, when considering more granular evidence considering the effects of individual and categories of interventions, there is less alignment.

Understandably, this has led to concerns about the meaning of this evidence, and questions about how it should be interpreted and used by practitioners, working to design and implement sanitation programs.

Partly in response to those concerns, WHO is convening an expert meeting in May this year, to develop a “consensus statement” around two specific questions:
• Are particular sanitation interventions more likely to have protective effects?
• What pre-conditions are likely to impact the effectiveness of these sanitation interventions?

The meeting will bring together researchers, from both life and social science backgrounds from around the world for two days of deliberations, informed by evidence and identifying points of agreement and contention. The MEDS team at the foundation strongly supports the organization of this meeting, and to make sure that issues relevant to practitioners are considered (and hopefully answered) during the discussions, we would like to invite you to share with us the most important questions you (and your teams) face when considering the use of evidence in program design.

The consensus meeting is scheduled to take place on May 24 and 25. To allow for review and incorporation into the agenda, the deadline for the submission of questions for consideration is end of day Thursday May 17.

There is no particular format for submission, although when we say we are looking for questions, we mean just that; a short sentence with a question mark at the end (no need to over-think it). If you are concerned that there is the possibility of mis-interpretation, you should feel free to provide some context and explanation.

Following the meeting, the results will be published and broadly disseminated.

We look forward to hearing from you what concerns you. If you have any questions about the process (or the scope) of this effort, please feel free to get in touch.

Best regards,
Jan Willem Rosenboom and Radu Ban.

Senior Program Officer on the Water, Sanitation and Hygiene team
Bill & Melinda Gates Foundation, Seattle, WA, USA
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  • KellyKBaker
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Re: Sanitation and health evidence: request for input into a consensus meeting

Hi Jan and Radu,

I realize this thread is aimed at practioners, but I just wanted to bring up another point as a sanitation research that would be worthwhile for considering at your meeting. Understanding the relative benefits of particular sanitation typologies and the pre-conditions that impact the effectiveness of interventions is important. However, there are some higher level issues raised by WASH B and SHINE, which are how much impact should anyone realistically expect ANY sanitation intervention to have when (a) young children, including infants, spend a substantial amount of time playing outside of the domestic house and yard, and (b) sanitation interventions do not install barriers between zoonotic vectors and young children and how do you measure the impact of sanitation. I am sure giving one household a latrine reduces the risk of child infection by some fraction of a point. Spatially clustering household latrine implementation probably has an even bigger impact. But there is a threshold of environmental safety that can be achieved without addressing domestic animal management and the blurring of public-private boundaries of life in crowded, low income settings. If researchers don't acknowledge that baseline and use appropriate tools that can distinguish between human and animal sources of enteric pathogens, you probably won't accurately quantify the true impact that can be gained from sanitation. WASH B and SHINE didn't really measure the impacts of their trials in a way that would allow extraction of this type of information, which still leaves the overall question as how much have we really learned about the impact of sanitation in a world swimming in animal shit.


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  • arno
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Re: Sanitation and health evidence: request for input into a consensus meeting

Jan Willem/Radu

The UNICEF publication by Joanna Esteves Mills and Oliver Cummings from 2016
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will be useful in categorizing the discussion. It provides evidence for WASH impact in the following areas:
complementary food hygiene
female psycho-social stress
maternal and newborne health
menstrual hygiene management
school attendance
oral vaccine performance

I think if one bundles access to safe water with sanitation then the evidence for improved health parameters will become significant. If on the other hand one restricts the lens to toilets and sanitation systems, the level of significance may drop mainly due to noise in the epidemiological data. Levels and types of sanitation create this variability.

This is shown in "The impact of sanitation on infectious disease and nutritional status: A systematic review and meta-analysis" by Freeman et al. 2017.
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That the British Medical Journal in its 2007 survey found 11300 of its readers voting that the sanitary revolution (clean water and sewage disposal) was the most significant medical milestone since 1840 is again evidence that safe water and sanitation must go hand in hand in the discussion surrounding evidence.


Arno Rosemarin PhD
Stockholm Environment Institute
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  • muench
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Re: Sanitation and health evidence: request for input into a consensus meeting

I very much agree with the points that Kelly and Arno have made. It's probably next to impossible to single out sanitation (and even limited to: toilets) on their own as there are so many more parameters that lead to a healthy, "sanitary" environment. Toilets are a very much needed piece of the puzzle but without the other pieces of the puzzle it may not have much measurable impact on the community's health.

Another thought that I had: Would this discussion on health evidence also consider how improved sanitation can help curb antimicrobial resistance (AMR)?

Arno summed up the issues nicely in various forum posts here:
We also wrote a paragaph about it in the Wikipedia article on AMR here:

Water, sanitation, hygiene [edit | edit source]

Infectious disease control through improved water, sanitation and hygiene (WASH) infrastructure needs to be placed at the center of the antimicrobial resistance (AMR) agenda. The spread of infectious diseases caused by inadequate WASH standards is a major driver of antibiotic demand in developing countries.[34] Growing usage of antibiotics together with persistent infectious disease levels have led to a dangerous cycle in which reliance on antimicrobials increases while the efficacy of drugs diminishes.[34] The proper use of infrastructure for water, sanitation and hygiene (WASH) can result in a 47–72 percent decrease of diarrhea cases treated with antibiotics depending on the type of intervention and its effectiveness.[34] A reduction of the diarrhea disease burden through improved infrastructure would result in large decreases in the number of diarrhea cases treated with antibiotics. This was estimated as ranging from 5 million in Brazil to up to 590 million in India by the year 2030.[34] The strong link between increased consumption and resistance indicates that this will directly mitigate the accelerating spread of AMR.[34] Sanitation and water for all by 2030 is Goal Number 6 of the Sustainable Development Goals.

An increase in hand washing compliance by hospital staff results in decreased rates of resistant organisms.[92]

And if sanitation is meant to include wastewater treatment (which it should), then more advanced treatment of hospital wastewater could be another route where sanitation can help to combat AMR.

Coming back to Jan-Willem's post where he said:
"Are particular sanitation interventions more likely to have protective effects?"
we should make sure we all have the same understanding what we mean with "sanitation interventions". I think many of the randomized controlled trials conducted recently looked only at toilet use at the household level, and maybe handwashing, but not at broader sanitation issues, such as animal feces (Kelly's post above), toilets away from home, hospital wastewater, municipal wastewater, drainage, solid waste, fecal sludge management.


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  • britta0812
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Re: Sanitation and health evidence: request for input into a consensus meeting

As a researcher in the field of sanitation, I am very much looking forward to reading the outcome of the May meetings. One aspect I thought I would add is around whether specific individuals are more susceptible to improvements in sanitation? I am in particular thinking about gender. A recent study of mine with Paul Lesmes shows that improvements in sanitation lead to improved child health, and that this effect is particularly driven by girls ( ). And we were not the only ones to find this gender dimension. Of course, this might be very much linked to the question on pre-conditions, but possibly interesting to consider.
Best wishes,
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  • MikeWebster
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Re: Sanitation and health evidence: request for input into a consensus meeting


I know this is "wet" waste focused but I was wondering whether there is any room for including the health benefits of improved solid waste management in this as well? We are a much neglected sector and if you think there are gaps in data for WASH, then solid waste is even greater. There is growing evidence around these health benefits - my organisation, WasteAid, has recently put together a briefing note that, whilst focusing on marine plastics, also takes a good look at the evidence linking improved solid waste and health:

I would also suggest there are close linkages between the potential of WASH interventions to improve health and improved solid waste management (e.g. building drainage systems that then block up with plastic waste, pit latrines blocking with plastic waste) so a holistic approach is important. I also think that the silos that separate WASH and solid waste are somewhat artificial - waste is waste after all.

Mike Webster
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  • Bjorn
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Re: [WG12] Evidence for Health Benefits from Improved Sanitation

Good to hear from you
Try the pdf below

PDF/Water Aid; Tackling the silent killer The case for sanitation

I googled Googeled it and it came up directly.
Fore more details try London School of Hygiene and Tropical Medicine.
They are definitively updated.

Best regards
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  • kunene47
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Re: [WG13] Evidence for Health Benefits from Improved Sanitation

My view to the stated sanitation questions are the following:

1. Will sanitation and related interventions improve health and reduce poverty ?

2. Are factors of safety and convenience likely to impact on sanitation intervention?

Kind regards
Lucas Kunene
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  • raviv1971
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Re: Sanitation and health evidence: request for input into a consensus meeting

Hi Jan & Radu,

Agree with all observations made above and specifically with Arno's thoughts on the topic. I live in India in Chennai, Tamil Nadu. Whilst on a volunteering visit to Vellore, one of India's most popular medical tourist destinations, I happened to spend some volunteering time on understanding WaSH issues in poorer informal settlements (slums), which did not clearly have Government provided infrastructure in terms of electricity & water, forget Sanitation facilities, the residents drew up their own area plan maps, open defecation was prevalent with men & children, women set on foot to more private & secure places early in the day . To my eye there was clearly visible evidence of stunting, but the mothers were in denial of the same because to them every child in that slum was the same height, which was their normal.

So for me objective base-lining for impact becomes critical, an objective base-lining is a first step to measure impact, a comprehensive gaps analysis for the entire sanitation value chain and not just containment & collection aspects of it needs to be done. Local primary health centers, hospitals & pharmacies should be the fulcrum of epidemological data collection which can be regressed with water, food quality & AMR. Ideally if we start measuring intervention impacts in a controlled populations like residential schools for example, we can maybe track more reliable, regressive and relevant data which can then possibly be the benchmark in gaps analysis. Until such time we have a controlled sample it becomes very difficult to associate impact with an intervention. Look forward to the report out on the May Conclave. Best wishes to all
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  • om
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Re: RE: Evidence for Health Benefits from Improved Sanitation

Dear Arno,
On behalf of WaterAid, we have written a blog in response to WASH Benefits trial outcomes. Find the attachment and I hope this will be helpful for Jan Willem and his team.

Note by moderator (EvM): the mentioned WASH Benefits study has been discussed in this discussion thread (2 pages):

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  • dmulatya
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Re: Sanitation and health evidence: request for input into a consensus meeting

Interesting and looking forward to read the outcomes of these deliberations.

Previous research has looked at sanitation-either improved or unimproved or presence of toilets and its impact on health outcomes but little has been done to structure research in a way that disaggregation of data is possible i.e investigate and compare causality between rural and peri-urban (SLUMS) settings. From literature, unplanned urbanization is one factor associated with poor health outcomes, and the determinants for poor health in urban settings are varied and diverse from rural populations. In slums overcrowding and limited access to basic services means that environmental reservoirs like water and sanitation become more conducive for microorganisms to survive and increase infectivity. Research covering only rural settings doesn't show residential disparities in how sanitation causes poor health outcomes. WHO's role would also include building capacities of public health and researchers to enhance developing countrys surveillance on sanitation data
Climate change could also impact on how well sanitation systems are functioning. Increased precipitation causes collapsing of sanitation facilities and fecal waste overflows in slums and rural areas. in developing countries, sanitation entrepreneurs using in protective equipment compromise their health and those of communities especially during such instances when illegal dumping of fecal waste is likely to happen. Operations and maintenance aspects of the sanitation technologies need to be buffered against climate change.
Those two comment address the question on pre-conditions that are likely to affect effectiveness of sanitation systems.
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  • KellyKBaker
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Re: RE: Evidence for Health Benefits from Improved Sanitation

This document nicely articulates some of the limitations in the WASHB and SHINE trials Om.

One other point to consider is that WASHB and SHINE might have had an impact on environmental contamination, even if they didn't impact health as expected (e.g. infection across multiple pathway). This is because both studies largely relied upon heavily on fecal coliforms (and some helminth ova assays) to measure intermediate environmental contamination. While fecal coliforms are relatively reliable proxies for risk for objects like drinking water and food, where the acceptable threshold of contamination is zero, indicator assays have been repeatedly shown to be poor proxies for assessing contamination levels for objects like soil, surface water, or objects.

From the microbial ecology point of view, it is highly improbable that there would NOT be E. coli or other coliforms everywhere. Bacteria are bacteria, and E. coli in particular are masters at niche tropism. They are shed by a broad variety of wild and domesticated animals, and are all over the place, and they survive in the environment far longer than most people are aware of. In our studies in Haiti, Kenya, and Iowa agricultural watersheds (in summer), E. coli and enterococci were detected in nearly 100% of all soil and surface water samples, at remarkably similar concentrations (evidence of quorum behavior, which is a topic for another thread). Furthermore, we find them even where obvious point or non-point fecal sources are not observed. If your indicator is omnipresent and non-obligate, it's not much of an indicator.

Much of the belief that E. coli doesn't last is probably derived from methodological issues. E. coli and many other types of bacteria can persist in the environment for prolonged periods of time in viable but non-recoverable states. The likelihood of being in a VBNR is influenced by the physical properties of the object, i.e. more likely on dry object surfaces, less likely in moist food or water. If bacteria are in a VBNR state, it requires a special enrichment step to trigger a replicative state. So studies that use indicator assays, without an enrichment step, to compare contamination levels from things like surfaces to food are reporting results that are biased by how well they account for VBNR conditions.

Ergo, the WASHB and SHINE environmental results are probably reasonable estimates of how well all of the different intervention arms affected drinking water quality, and thus drinking water quality linked health effects. But it's impossible at this point to know whether the sanitation arms did in fact reduce human-caused environmental contamination across ecological pathways (soil, objects). Proving this would go a long ways towards proving impact, even in the absence of health effects. I wouldn't be surprised if one of more of these groups have something up their sleeve though.
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