Environmental risk factors and the development of trachomatous trichiasis in Dalocha District, Central Ethiopia: a case-control study

Background: Trachoma is the second leading cause of blindness in Ethiopia. Even in trachoma hyperendemic areas, not all member of the community develop trichiasis. Whether this is due to uneven exposure or other factors is not clear. This necessitated a case-control study to see the extent of exposure among these groups. Objective: The purpose of the study was to assess the extent of exposure to known environmental risk factors among cases with trachomatous trichiasis and age, sex and location matched controls with no trachomatous trichiasis in Dalocha District, Central Ethiopia. Methods: all patients with clinically diagnosed trachomatous trichiasis (TT) according to the WHO definition for TT and an equal number of sex and location matched controls with no trachomatous trichasis were subjected to an interviewer administered questionnaire consisting of questions assessing family size, number of children raised, frequency of face washing, water sources and distance from it in minutes, location of kitchen, toilet waste disposal, place for cattle at night and some more considered to be related with repeated trachomatous infection. Results: One hundred ninety seven cases with TT and an equal number of controls were the study subjects. Regression analysis of individual risk factors showed that irregular face washing practice (odds ratio (OR))=2.27;95% confidence interval (CI):1.48-3.49) and being illiterate (OR=0.34;CI:0.18-0.64) were significantly associated with the development of TT. Regarding face washing, this significance was also maintained in a logistic regression analysis of the variables where the type of water used for washing and the frequency of cooking were also positively associated with TT. Conclusion: Improved educational status and regular face washing of the community may decrease the likelihood that people will be at risk of developing TT and its blinding complications. [Ethiop.J.Health Dev. 2002;16(3):287-293]