Environ Health Perspect. 2010 Aug 12.
Impact of a City-Wide Sanitation Programme in Northeast Brazil on Intestinal Parasites Infection in Young Children.
Barreto ML, et al.
Background: Sanitation affects health, especially of young children. Residents of Salvador, in Northeast Brazil had a high prevalence of intestinal parasites. A city-wide sanitation intervention started in 1996 aimed to raise the level of sewer coverage from 26% to 80% of households. We present the results of a study to evaluate the impact of this intervention on the prevalence of Ascaris lumbricoides, Trichuris trichuria and Giardia duodenalis infections in pre-school children.
Methods: The evaluation was composed of two cross-sectional studies (1998 and 2003-4), each of a sample of 681 and 976 children aged 1-4 years, respectively. Children were sampled from 24 sentinel areas chosen to represent the range of environmental conditions in the study site. Data were collected using an individual/household questionnaire, and an environmental survey was conducted in each area before and after the intervention to assess basic household and neighborhood sanitation conditions. Stool samples were examined for the presence of intestinal parasites. The effect of the intervention was estimated by hierarchical modelling, fitting a sequence of multivariate regression models.
Findings: The prevalence of A. lumbricoides infection was reduced from 24.4% to 12.0%, T. trichuria from 18.0% to 5.0% and G. duodenalis from 14.1% to 5.3%. Most of this reduction appeared to be explained by the increased coverage of each neighborhood by the sewerage system constructed during the intervention. The key explanatory variable was thus an ecological measure of exposure and not household-based, suggesting that the parasite transmission prevented by the program was mainly in the public (as opposed to the domestic) domain.
Conclusion: This study, using advanced statistical modelling to control for individual and ecological potential confounders, demonstrates the impact on intestinal parasites of sanitation improvements implemented at the scale of a large population.
Sanitation Updates 