Incidence and progression of trachomatous scarring in a cohort of children in a formerly hyper-endemic district of Tanzania

Expanding a photographic grading system for trachomatous scarring

BACKGROUND

The purpose was to assess an expansion of a previously published photographic four-step severity grading scale for trachomatous scarring (TS).

METHODS

Images of everted eyelids of adult women in Tanzania were graded for the presence and severity of TS. The previous S3 grade was subdivided into two categories: S3A, one-third to <50% of the upper eyelid conjunctiva scarred; and S3B, 50% to <90%. The reliability and ease of use were evaluated. This new categorisation was then applied to images taken of the same women 5 y prior to evaluate whether it could help detect previously undetected progression.

RESULTS

In total, 142 eyes at baseline and 418 eyes at follow-up after 5 y were graded as S3. Interobserver agreement using the expanded scarring grading scale was a kappa of 0.86. At baseline, 51 (35.9%) eyes were S3A and 91 (64.1%) were S3B. At follow-up after 5 y, 36.6% of the eyes that were previously documented as not having progressed were now detected as having progressed from S3A to S3B. S3B images were more likely to progress to S4 compared with S3A (OR 4.6, 95% CI 2.1 to 9.9).

CONCLUSIONS

Adding S3A and S3B is reliable and detects more scarring progression. It will be beneficial for future studies analysing TS in photographs.

Utility of photography for trachoma surveys: A systematic review

As trachoma prevalence declines worldwide, performing field surveys with trained trachoma graders to validate its elimination becomes challenging. Graded conjunctival images could be used to train graders, validate field grades, and replace field grading. We review the use of photography to capture conjunctival images for the detection of trachomatous inflammation-follicular (TF) and -intense (TI), Trachomatous trichiasis (TT), and eyelid contour abnormalities. Literature searches were conducted between October 29, 2020 and February 15, 2021. We abstracted kappa scores for agreement between field and image graders, between field graders, and between image graders. The median kappa was calculated for studies discussing grading for TF and TI. Twenty-one studies were included - 19 described the use of imaging tools for grading TF and TI; 1 discussed TT; and 1 discussed eyelid contour abnormalities. For agreement between field and image graders, median kappa for TF was 0.71 (range: 0.57-0.92) and TI was 0.67 (0.37-0.74); between image graders, median kappa for TF was 0.65 (0.37-0.78) and TI was 0.76 (0.39-0.83); and between field graders, median kappa for TF was 0.86 (0.73-1) and TI was 0.82 (0.73-0.91). There is potential for the use of photography for trachoma prevalence surveys. Further research is warranted, particularly for TT and using newer smartphones.

The population-based prevalence of trachomatous scarring in a trachoma hyperendemic setting: results from 152 impact surveys in Amhara, Ethiopia

BACKGROUND

Trachomatous scarring (TS) results from repeated infection with the bacterium Chlamydia trachomatis. Pronounced scarring is an underlying cause of trachomatous trichiasis (TT) that can lead to blindness. Since the condition is irreversible, TS in adults has been considered a marker of past exposure to trachoma infection. The aim of this report was to estimate the population-based prevalence of TS within Amhara, Ethiopia, a region with a historically high burden of trachoma.

METHODS

District-level multi-stage cluster surveys were conducted in all districts between 2010 and 2015 to monitor the impact of approximately 5 years of trachoma interventions. Approximately 40 households were sampled per cluster and all participants ages ≥ 1 year were graded for the 5 World Health Organization simplified signs. Before each survey round, trachoma graders participated in a 7-day training and reliability exam that included cases of TS. TS prevalence estimates were weighted to account for sampling design and adjusted for age and sex using post-stratification weighting.

RESULTS

Across the 152 districts in Amhara, 208,510 individuals ages 1 year and older were examined for the signs of trachoma. Region-wide, the prevalence of TS was 8.2 %, (95 % Confidence Interval [CI]: 7.7-8.6 %), and the prevalence among individuals ages 15 years and older (n = 110,137) was 12.6 % (95 % CI: 12.0-13.3 %). District-level TS prevalence among individuals ages 15 years and older ranged from 0.9 to 36.9 % and was moderately correlated with district prevalence of TT (r = 0.31; P < 0.001). The prevalence of TS increased with age, reaching 22.4 % among those ages 56 to 60 years and 24.2 % among those ages 61 to 65 years. Among children ages 1 to 15 years TS prevalence was 2.2 % (95 % CI: 1.8-2.8 %), increased with age (P < 0.001), and 5 % of individuals with TS also had trachomatous inflammation-intense (TI).

CONCLUSIONS

These results suggest that Amhara has had a long history of trachoma exposure and that a large population remains at risk for developing TT. It is promising, however, that children, many born after interventions began, have low levels of TS compared to other known trachoma-hyperendemic areas.