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Trachoma is the leading infectious cause of blindness worldwide and data are needed on the epidemiological characteristics of active and residual disease in hyperendemic areas. This study describes the epidemiological characteristics of trachoma in Central Tanzania. Active, inflammatory disease peaks in pre-school children, with 60% showing signs of trachoma. Evidence of past infection, scarring, trichiasis, and corneal opacity, rose with age. In this population, 8% of those over age 55 had trichiasis/entropion. Females of all ages had more trachoma than males, with a fourfold increased risk of trichiasis observed in females. Women who were taking care of children appeared to have more active disease than non-caretakers. Clear evidence of clustering of trachoma by village, and within village, by neighbourhood was found. Clustering persisted even after accounting for differences in distance to water, local religion, and proportion of children with unclean faces. These findings have important implications for a trachoma control strategy.

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Trachoma, an ocular infection caused by Chlamydia trachomatis, is the second leading cause of blindness worldwide. The blinding sequelae, which occur in middle age, are felt to be the result of numerous or lengthy episodes of severe inflammatory trachoma in childhood. Risk factors for constant, severe trachoma were identified in a group of children enrolled in a longitudinal study in Kongwa, Tanzania, where villages were randomized in a clinical trial of mass treatment and a behavior modification campaign. In 1989, each of 1,417 randomly selected children had photographs taken of an upper eyelid for determination of their trachoma status. The photographs were graded by a reader who was masked as to the village and date of each photograph. Risk factor data on the family's socioeconomic status, distance to water, and hygiene practices were obtained at baseline. Follow-up examinations occurred 2, 6, and 12 months from baseline. Data from all four time points were available for 82% of the children enrolled. Overall, 10% of the children had constant, severe trachoma, defined as severe trachoma at three or four examinations. The odds ratio for severe trachoma was 1.9 for female children (95% confidence interval 1.3-2.7). Familial cattle ownership and having one or more siblings with trachoma at baseline were also significantly related to the odds of having severe trachoma. Children with a sustainably clean face had lower odds (odds ratio = 0.4, 95% confidence interval 0.3-0.7). A subgroup of 10% of children in these hyperendemic communities always seemed to have severe trachoma, despite enrollment in a mass treatment campaign. Improved face-washing plus antibiotic treatment may decrease the likelihood that these children will be at risk for blinding complications in adulthood.

Trichiasis/Entropion are the severe consequences of chronic trachoma during early life. Blindness and vision loss is preventable with timely lid surgery to correct trichiasis. In a trachoma hyperendemic region of Central Tanzania, a two year follow-up survey was conducted among 205 women with trichiasis to determine the proportion who had had surgery and the barriers to having surgery. Only 18% of the women had undergone surgery by the 2 year follow-up. Those who had surgery tended to report more eye problems at baseline and have more corneal opacities at baseline. Barriers preventing women from going to surgery were costs, problem of children left at home alone, and difficulties in identifying someone to accompany them to the health center. Over 2/3 of those who had surgery reported a significant decrease in pain, improvement of vision, and improved ability to carry out activities of daily life. Ways to improve compliance with recommendations for trichiasis surgery need to be developed.