The Trachoma Control Program in Amhara region, Ethiopia, scaled up the surgery, antibiotics, facial cleanliness, and environmental improvement (SAFE) strategy in all districts starting in 2007. Despite these efforts, many districts still require additional years of SAFE. In 2017, four districts were selected for the assessment of antibody responses against Chlamydia trachomatis antigens and C. trachomatis infection to better understand transmission. Districts with differing endemicity were chosen, whereby one had a previous trachomatous inflammation-follicular (TF) prevalence of ≥ 30% (Andabet), one had a prevalence between 10% and 29.9% (Dera), one had a prevalence between 5% and 10% (Woreta town), and one had a previous TF prevalence of < 5% (Alefa) and had not received antibiotic intervention for 2 years. Survey teams assessed trachoma clinical signs and took conjunctival swabs and dried blood spots (DBS) to measure infection and antibody responses. Trachomatous inflammation-follicular prevalence among children aged 1-9 years was 37.0% (95% CI: 31.1-43.3) for Andabet, 14.7% (95% CI: 10.0-20.5) for Dera, and < 5% for Woreta town and Alefa. Chlamydia trachomatis infection was only detected in Andabet (11.3%). Within these districts, 2,195 children provided DBS. The prevalence of antibody responses to the antigen Pgp3 was 36.9% (95% CI: 29.0-45.6%) for Andabet, 11.3% (95% CI: 5.9-20.6%) for Dera, and < 5% for Woreta town and Alefa. Seroconversion rate for Pgp3 in Andabet was 0.094 (95% CI: 0.069-0.128) events per year. In Andabet district, where SAFE implementation has occurred for 11 years, the antibody data support the finding of persistently high levels of trachoma transmission.

BACKGROUND:After approximately 5 years of SAFE (surgery, antibiotics, facial cleanliness, environmental improvement) interventions for trachoma, hyperendemic (trachomatous inflammation-follicular (TF) ≥30%) districts remained in Amhara, Ethiopia. This study's aim was to characterize the epidemiology of Chlamydia trachomatis (Ct) infection and load among pre-school aged children living under the SAFE strategy. METHODS:Conjunctival swabs from a population-based sample of children aged 1-5 years collected between 2011 and 2015 were assayed to provide Ct infection data from 4 endemic zones (comprised of 58 districts). Ct load was determined using a calibration curve. Children were graded for TF and trachomatous inflammation-intense (TI). RESULTS:7,441 children were swabbed in 4 zones. TF and TI prevalence were 39.9% (95% confidence Interval [CI]: 37.5%, 42.4%), and 9.2% (95% CI: 8.1%, 10.3%) respectively. Ct infection prevalence was 6.0% (95% CI: 5.0%, 7.2%). Infection was highest among children aged 2 to 4 years (6.6%-7.0%). Approximately 10% of infection occurred among children aged 1 year. Ct load decreased with age (P = 0.002), with the highest loads observed in children aged 1 year (P = 0.01) vs. aged 5 years. Participants with TF (P = 0.20) and TI (P<0.01) had loads greater than individuals without active trachoma. CONCLUSIONS:In this hyperendemic setting, it appears that the youngest children may contribute in meaningful ways towards persistent active trachoma.

Background

World Health Organization (WHO) recommendations for starting and stopping mass antibiotic distributions are based on a clinical sign of trachoma, which is indirectly related to actual infection with the causative agent, Chlamydia trachomatis.

Methods

This study aimed to understand the effect of SAFE (surgery, antibiotics, facial cleanliness, and environmental improvement) interventions on ocular chlamydia in Amhara, Ethiopia, by describing the infection prevalence in a population-based sample of children aged 1-5 years. Trachoma surveys were conducted in all districts of Amhara, from 2011 to 2015 following approximately 5 years of SAFE. Ocular swabs were collected from randomly selected children to estimate the zonal prevalence of chlamydial infection. The Abbott RealTime polymerase chain reaction assay was used to detect C. trachomatis DNA.

Results

A total of 15632 samples were collected across 10 zones of Amhara. The prevalence of chlamydial infection in children aged 1-5 years was 5.7% (95% confidence interval, 4.2%-7.3%; zonal range, 1.0%-18.5%). Chlamydial infection and trachomatous inflammation-intense (TI) among children aged 1-9 years were highly correlated at the zonal level (Spearman correlation [r] = 0.93; P < .001), while chlamydial infection and trachomatous inflammation-follicular were moderately correlated (r = 0.57; P = .084).

Conclusions

After 5 years of SAFE, there is appreciable chlamydial infection in children aged 1-5 years, indicating that transmission has not been interrupted and that interventions should continue. The sign TI was highly correlated with chlamydial infection and can be used as a proxy indicator of infection.