The majority of world's population have poor access to proper facilities to dispose of human excreta which leads to many infectious diseases, including diarrhoea. According to the World Health Organisation diarrhoeal illness is one of the leading causes of child morbidity and mortality, leading to an estimated 1.8 million deaths annually (WHO, 2005). The pathogens causing diarrhoeal disease are transmitted by ingestion of human excrement, through 'fluids, fingers, fields and flies'. Improved sanitation facilities are believed to help reduce diarrhoea by removing human excrement from the environment.
Previous systematic reviews suggest that improved sanitation interventions are effective in reducing diarrhoea (Fewtrell et al., 2005; Waddington et al., 2009). Sanitation interventions included in this review are those which introduce or expand latrine facilities for the collection and disposal of human excreta.
The review assesses and synthesises impact of human excreta disposal interventions on controlling diarrhoea disease.
The authors included randomized, quasi-randomized, and non-randomized controlled studies from any regions assessing effect of improved human excreta disposal interventions on diarrhoea disease. The authors conducted systematic search in Cochrane Infectious Disease Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), and electronic database search in MEDLINE, EMBASE, and LILACS so on. The authors checked reference lists, contacted experts and referred to the proceedings of conferences. The authors searched in English and Chinese language databases. Due to vast differences in the included studies like difference in study population, settings and interventions, Meta analysis is not conducted and results are summarised using narrative synthesis.
The authors included 13 studies from China, rural USA, The Ivory Coast, Bangladesh, Kenya and Nigeria.
- The majority of studies (11 out of 13) suggest positive effects of interventions for disposal of human excreta on reduction of diarrhoea. One study assessed the effect of sanitation on mortality caused by diarrhoea, suggesting an 85 percent reduction in mortality due to improved sanitation facilities.
- However, the authors highlight the low quality of the existing evidence on diarrhoeal impacts of sanitation interventions. Most studies are insufficiently powered to detect statistically significant effects, so the results can only be interpreted to indicate the likely direction of effect on diarrhoeal disease in such settings.
- The authors recommend that future studies based on randomised allocation of the intervention (RCTs) are needed, together with longer-term programme evaluations using rigorous designs to attribute diarrhoeal outcomes to sanitation interventions, in order assess adequately their effectiveness, sustainability and scalability.
This systematic review uses clear and transparent methods of search, inclusion and methods of analysis. Important innovations of the review are the search in Chinese language databases and the assessment of unit of analysis errors contained in the included studies. The review uses transparent criteria to assess the quality of included studies, and reports results appropriately.