Environmental sanitary interventions for preventing active trachoma

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.

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

We searched the Cochrane Central Register of Controlled Trials - CENTRAL in The Cochrane Library (Issue 2, 2007), MEDLINE (1966 to July 2007), EMBASE (1980 to July 2007), LILACS (July 2007), reference list of trials and the Science Citation Index. We also contacted agencies, experts and researchers in trachoma control.

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.

Two authors independently extracted data and assessed the quality of trials. Study authors were contacted for additional information. Four trials met the inclusion criteria but meta-analysis was not conducted due to heterogeneity of the studies.

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. Another study revealed that health education on personal and household hygiene reduced the incidence of trachoma such that the odds of reducing trachoma in the health education village was about twice that of the no intervention village. However, all the studies have some methodological concerns relating to concealment of allocation and non-consideration of clustering effect in data analysis.

The role of insecticide spray as a fly control measure in reducing trachoma remains unclear. Latrine provision as a fly control measure has not demonstrated significant trachoma reduction. Health education may be effective in reducing trachoma. There is a dearth of data to determine the effectiveness of all aspects of environmental sanitation in the control of trachoma.