Environmental sanitary interventions for preventing active trachoma

Abstract

Background: Trachoma is a major cause of avoidable blindness. It is responsible for about six million blind people worldwide, mostly in the poor communities of developing countries. One of the major strategies advocated for the control of the disease is the application of various environmental sanitary measures to such communities.

Objectives: To assess the evidence for the effectiveness of environmental sanitary measures on the prevalence of active trachoma in endemic areas.

Search methods: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 9), MEDLINE (January 1950 to September 2011), EMBASE (January 1980 to September 2011), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to September 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (www.clinicaltrials.gov). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 23 September 2011. We checked the reference list of included trials and the Science Citation Index. We also contacted agencies, experts and researchers in trachoma control.

Selection criteria: We included randomised and quasi-randomised controlled trials comparing any form of environmental hygiene measures with no measure. These hygiene measures included fly control, provision of water and health education. Participants in the trials were people normally resident in the trachoma endemic areas.

Data collection and analysis: Two authors independently extracted data and assessed the quality of the included trials. Study authors were contacted for additional information. Six trials met the inclusion criteria but we did not conduct meta-analysis due to heterogeneity of the studies.

Main results: We included six studies with a total of 12,294 participants from 79 communities. Two studies that assessed insecticide spray as a fly control measure found that trachoma is reduced by at least 55% to 61% with this measure compared to no intervention. However, another study did not find insecticide spray to be effective in reducing trachoma. One study found that another fly control measure, latrine provision, reduced trachoma by 29.5% compared to no intervention; this was, however, not statistically significantly different and findings have not been confirmed by a more recent study. Another study revealed that health education reduced the incidence of trachoma. These findings were not confirmed by a second study, however, which found that a modest health education programme with modest water supply did not reduce trachoma. However, all the studies have some methodological concerns.

Authors' conclusions: There is some evidence from two trials that insecticides are effective in reducing trachoma, however, this effect was not demonstrated in another trial that used insecticides. Two trials on latrine provision as a fly control measure have not demonstrated significant trachoma reduction. Health education had shown significant reduction of trachoma in one study but another study did not demonstrate similar findings. Generally there is a dearth of data to determine the effectiveness of all aspects of environmental sanitation in the control of trachoma.

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Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.

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Risk of bias summary: review authors' judgements about each risk of bias item for each included study.