Impact of a city-wide sanitation intervention in a large urban centre on social, environmental and behavioural determinants of childhood diarrhoea: analysis of two cohort studies.
BACKGROUND
Poor socioeconomic status (SES) increases diarrhoea risk, mostly mediated by lack of sanitation, poor infrastructure and living conditions. The effectiveness of a city-wide sanitation intervention on diarrhoea in a large urban centre in Northeast Brazil has recently been demonstrated. This article aims to explore how this intervention altered the magnitude of relative and attributable risks of diarrhoea determinants and the pathways by which those factors affect diarrhoea risk.


METHODS
We investigated determinants of prevalence of diarrhoea in two cohort studies conducted before and after the intervention. Each study enrolled pre-school children followed up for 8 months. For both cohorts, we calculated relative, attributable and mediated risks of diarrhoea determinants by a hierarchical effect decomposition strategy.


RESULTS
The intervention reduced diarrhoea and also changed attributable and relative risks of diarrhoea determinants by altering the pathways of mediation. Before the intervention SES was a major distal diarrhoea determinant (attributable risk: 24%) with 90% of risk mediated by other factors, mostly by lack of sanitation and poor infrastructure (53%). After the intervention, only 13% of risk was attributed to SES, with only 42% mediated by other factors (18% by lack of sanitation and poor infrastructure).


CONCLUSIONS
The intervention reduced diarrhoea risk by reducing direct exposure to unfavourable sanitation conditions. At the same time it altered the effect and mediation pathways of most distal diarrhoea determinants, especially SES. This finding corroborates the importance of public sanitation measures in reducing the impact of poverty on diarrhoea. It also underlines the value of studying the impact of public health interventions to improve our understanding of health determinants.
Genser
Bernd
B
Instituto de Saúde Coletiva, Federal University of Bahia, Salvador, Brazil. bernd.genser@bgstats.com
Strina
Agostino
A
dos Santos
Lenaldo A
LA
Teles
Carlos A
CA
Prado
Matildes S
MS
Cairncross
Sandy
S
Barreto
Mauricio L
ML
D001938:Brazil; D002675:Child, Preschool; D002947:Cities; D003906:Developing Countries; D003967:Diarrhea / Q000191:economics / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D015233:Models, Statistical; D015999:Multivariate Analysis; D011203:Poverty; D011446:Prospective Studies; D012306:Risk; D012923:Social Class; D018505:Waste Management; D018508:Water Purification