Assessing trachoma elimination progress in districts with persistent trachoma, Western Province, Zambia

Background: Trachoma is a public health problem in Zambia. We aimed to estimate the prevalence of trachomatous inflammation-follicular (TF) in 1-9-y-olds and of trachomatous trichiasis (TT) in >= 15-y-olds after the implementation of trachoma elimination interventions to determine if the trachoma elimination thresholds had been achieved: <5% for TF in 1-9-y-olds and <0.2% TT for >= 15-y-olds. Methods: Two rounds of impact prevalence surveys in two evaluation units (EUs) comprising four districts of Western Province were conducted; the first in 2018, the second in 2023. All individuals aged >= 1 year from 30 households of 24 clusters in each EU were examined for trachoma. Data were captured electronically. Results In 2018, TF prevalence in 1-9-y-olds was 13.9% in Kalabo/Sikongo and 17.9% in Shang'ombo/Sioma. Following further interventions, TF prevalence among 1-9-y-olds in 2023 was 7.7% and 12.5%, respectively. TT prevalences in >= 15-y-olds were 0.10% and 0.79% in 2018, and 0.4% and 0.2% in 2023, respectively. Conclusions: These EUs did not attain trachoma elimination thresholds as a public health problem. They fulfilled the WHO definition for persistent trachoma. Therefore, they warrant further investigation, including collection of Chlamydia trachomatis infection data, to inform future programmatic decision-making. Further TT surgical services are also needed.