Ocular Chlamydia trachomatis infection and infectious load among pre-school aged children within trachoma hyperendemic districts receiving the SAFE strategy, Amhara region, Ethiopia.

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

Population-Based Prevalence of Chlamydia trachomatis Infection and Antibodies in Four Districts with Varying Levels of Trachoma Endemicity in Amhara, Ethiopia.

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 &lt; 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 &lt; 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 &lt; 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

Cluster specific <i>Chlamydia trachomatis</i> (Ct) infection prevalence in Woreta Town district, Amhara, Ethiopia 2021.

Map created in ArcGIS Pro 2.2.6 (ESRI, Redlands, CA) using a shapefile sourced from the GADM database (gadm.org).</p

District prevalence (95% confidence intervals) of key water, sanitation, and hygiene (WASH) indicators, Metema and Woreta Town districts, Amhara, Ethiopia, 2021.

District prevalence (95% confidence intervals) of key water, sanitation, and hygiene (WASH) indicators, Metema and Woreta Town districts, Amhara, Ethiopia, 2021.</p

Age-seroprevalence among children ages 1 to 9 years in Metema and Woreta Town districts, Amhara, Ethiopia, 2021.

Age-seroprevalence among children ages 1 to 9 years in Metema and Woreta Town districts, Amhara, Ethiopia, 2021.</p

Selected districts for the wait and watch surveillance approach, Amhara, Ethiopia 2021.

Map created in ArcGIS Pro 2.2.6 (ESRI, Redlands, CA) using a shapefile sourced from the GADM database (gadm.org).</p

Sample sizes for wait and watch districts, Amhara, Ethiopia, 2021.

Sample sizes for wait and watch districts, Amhara, Ethiopia, 2021.</p

Fig 4 -

Median MFI Distribution of A) Pgp3 and B) CT694 among children ages 1 to 9 years in Metema and Woreta Town districts, Amhara, Ethiopia, 2021.</p

Seroconversion rates (SCR) per 100 child-years to Pgp3 and CT694 among children ages 1 to 9 years in Metema and Woreta Town districts, Amhara, Ethiopia, 2021.

Seroconversion rates (SCR) per 100 child-years to Pgp3 and CT694 among children ages 1 to 9 years in Metema and Woreta Town districts, Amhara, Ethiopia, 2021.</p

Age-specific prevalence of TF among children ages 1 to 9 years, Amhara, Ethiopia, 2021.

Age-specific prevalence of TF among children ages 1 to 9 years, Amhara, Ethiopia, 2021.</p