Faecal-oral paradigm: part 3

Stagnant water in a setting of poor urban sanitation in a Ljegun suburb, Lagos
Source: (Reuters, 2008)

Within this mini-series of blogs  I have outlined the discovery of the faecal-oral paradigm within the urban setting (part 1), and the current state of affairs within Urban Africa (part 2). This blog discuss the range of arguments as to the most effective methods to restrict faecal-oral transmission. Much debate has ensued over recent decades on which factors are required to achieve maximum impact. Furthermore, problems in identifying these factors have often been exacerbated by study limitations whereby they have often focused on one type of service improvement at one level (i.e community pumps or household supply) with often inefficient study size (Esrey in 1996).

At its simplest level, strategies for reducing diarrhoeal disease must break the source-receptor pathways between faecal-oral transmission between sewage and the point of consumption. In a study in 1985, Esrey at al. found that investment in water supply and excreta disposal can lead do significant reductions in diarrhoeal related morbidity and mortality, with investments in water quantity and quality appearing particularly effective. Drawing on comparisons with how improvements in the physical environment in reducing diarrhea and cholera in 19th century Europe (see part 1), Esrey et al. argue that these improvements still hold particular significance. In a review of 67 studies diarrhoeal morbidity was reduced by 25% for improved water availability, 22% for improved excreta disposal and 16% from water quality improvements. .

However, other studies, including one by Esrey in 1996 which collected and analysed data from eight countries including Sub-Saharan Africa, argue that improved sanitation brings 'overwhelmingly larger benefits to health than improved water supplies' with positive health impacts at all levels of existing water supply, whereas improvements in water (both quality and quantity) did not result in health impacts unless tied with improvements in sanitation. However, that does not mean water improvements should be ignored with the effect of both water and sanitation improvements combined the greatest.

Similarly results were found in a review of 144 studies on the effects of improved water supply and sanitation on a selection of widespread waterborne diseases including diarrhea (Esrey et al. 1991) The review focused on four main mechanisms for improving health:

1. Improvements in sanitation and excreta disposal
2. Water quality
3. Personal hygiene
4. Domestic hygiene

The paper concluded that improving one or more of these factors, can substantially reduced the levels of morbidity and severity of selected diseases with reductions ranging from 26% for diarrhea to 78% for dracunculiasis (WHO definition here). Reductions in mortality were even more impressive, with a median reduction specifically occurring from diarrhea of 65%. Interestingly, the study also found that improvements in excreta disposal and water quantity, both of which are important for improving hygiene practices, had greater impacts than improvements in water quality. Arguments such as these echo the findings of the original Drawers of Water study which which highlighted how across many examples, water quantity is more important in improving health than water quality. Improvements in health resulted from improved quantity regardless of quality Thompson et al., (2000), with greater supply increasing the amount of water available for personal and household hygiene.

Furthermore, as highlighted in my earlier blogs on access to water, interventions do not automatically lead to their actual usage and uptake. If instillation of new facilities do not change behaviors, remain underused, break down and do not work the resulting impacts on improving health and water supply will be negligible (Esrey et al. 1991). Therefore the paper recommends not only a greater focus on excreta disposal and use of water for personal and domestic hygiene but with a focus on access with facilities built as close to the home as possible coupled with an emphasis on hygiene education . A clear example of a need for this focus is within rural Ethiopia where accessibility is severely undermined by water availability and collection times, accentuated by the inability of the poorest to release labour for water collection. As a result, although the use of water for drinking and cooking (which is very low already) does not decline in the dry season, alarmingly, water use for personal health and hygiene is elastic and forfeited (Tucker et al. 2014). 

This blog has outlined  the main arguments surrounding the most effective methods to restrict faecal-oral transmission, morbidity and mortality, improving public health within urban areas. Coming full circle back to the start of this mini-series of blogs on the faecal-oral paradigm, it is interesting to note 

how many of the suggestions made by John Snow to tackle Cholera in 19th century urban Britain still underpin modern approaches to the problem. Snow's preventative measures focused on thorough personal hygiene and the controlling of the disease through the physical environment. Yet, poor health resulting from the faecal-oral paradigm remains as prevalent as ever in urban areas within Africa, particularly within Sub-Saharan Africa.