Trachomatous scarring among children in a formerly hyper-endemic district of Tanzania

BACKGROUND: Associations between repeated ocular infections with Chlamydia trachomatis in childhood and conjunctival scarring in adulthood are well established. Trachomatous scarring (TS) in children has also been observed in hyper-endemic areas, but data are scant regarding childhood scarring in areas where trachoma has been reduced to hypo-endemic levels. METHODS/PRINCIPLE FINDINGS: In this cross-sectional study, a random sample of children, ages 1–9 years, were selected from 38 communities in the formerly hyper-endemic district of Kongwa, Tanzania. Each participant received an ocular examination and eye-swab test for C. trachomatis infection. Conjunctival photographs were taken and analyzed at 5x magnification to determine scarring presence and severity. Community-level case clustering was assessed using intra-class correlation coefficients, and associations between TS presence and demographic/clinical factors were assessed using contingency table analyses. 1,496 children (78% of eligible) participated in this study. The mean age was 5.5 years and 51% were female. Scarring prevalence was 2.1% (95% CI: 1.5%– 3.0%). The prevalence of follicular trachoma and ocular C. trachomatis infection were 3.2% and 6.5%, respectively. Most TS cases (68.7%) fell into the mildest category, grade S1. 18.7% were grade S2; 12.6% were grade S3. No significant associations were seen between TS presence and age, sex, follicular trachoma, or active ocular C. trachomatis infection (p-values: 0.14, 0.48, 0.27, 0.15, respectively). Thirty communities (78.9%) had 0–1 TS cases, and the most seen in any single community was four cases. Three years ago, follicular trachoma prevalence averaged 4.9% in communities with 0–1 TS cases, but 7.6% in communities with 2–4 TS cases (p-value: 0.08). CONCLUSIONS: In this formerly hyper-endemic district of Tanzania, TS was rare in 1–9 year-olds and usually mild when present. Communities with higher rates of follicular trachoma in the past were more likely to have ≥2 cases of scarring, but the association was not statistically significant.