Prevalence of Ocular Chlamydia trachomatis Infection in Amhara Region, Ethiopia, after 8 Years of Trachoma Control Interventions

Abstract

Although trachoma mass drug administration (MDA) programs target ocular Chlamydia trachomatis, the global trachoma control program does not monitor infection as a measure of impact but instead relies on monitoring clinical indicators. This study aimed to monitor the prevalence of ocular C. trachomatis among a population-based sample of children ages 1–5 years throughout Amhara, Ethiopia, a region that has received approximately 8 years of annual MDA as part of trachoma control. Between 2014 and 2021, trachoma impact surveys and surveillance surveys were conducted in all 156 districts of Amhara using a multistage cluster randomized methodology. Certified graders assessed individuals ages ≥ 1 year for trachomatous inflammation-follicular (TF), and a random subset of children ages 1–5 years also provided a conjunctival swab. Polymerase chain reaction was used to test for C. trachomatis. A total of 28,410 conjunctival swabs were collected from children ages 1–5 years across Amhara. The regional C. trachomatis infection prevalence was 4.7% (95% uncertainty interval: 4.3–5.1%). Infection was detected in all 10 zones of the region and ranged from 0.2% in Awi Zone to 11.9% in Waghemra Zone. Infection was detected in 17 (26%) districts with a TF prevalence < 10% and in 7 (21%) districts with a TF prevalence < 5%. Through programmatic monitoring of C. trachomatis infection, this study demonstrated that considerable infection remained throughout Amhara despite approximately 8 years of trachoma interventions and that enhanced interventions such as more frequent than annual MDA will be needed if elimination thresholds are to be reached.

Ongoing transmission of trachoma in low prevalence districts in Mozambique: Results from four cross-sectional enhanced impact surveys, 2022

“…The observed ocular Ct infection prevalence (1.1%) was similar to those found in districts with TF < 5% in recent trachoma prevalence surveys in the Amhara Region of Ethiopia that measured ocular Ct infection using conjunctival swabs among children aged 1-5 years. 33 Our estimated Pgp3 seroconversion rate (1.9 per 100 children per year) was also similar to a preliminary operational SCR threshold of 1.5 per 100 children per year found to correspond to a TF prevalence below 5% based on modeling of data from nine trachoma-endemic populations. 18 These ndings support the conclusion that MDA in this district can be discontinued.…”

Wait and watch: A trachoma surveillance strategy from Amhara region, Ethiopia

“…Technicians were masked to whether a sample was from a participant or was an air swab and masked to the district or trachoma clinical status of the individual providing the swab. Laboratory quality control procedures have been published previously [ 7 , 9 ].…”

Trachoma Control: A Glass Half Full?

“…This same report tells a different story in eastern Amhara, where the majority of districts still have clinical activity well above the WHO threshold for control. 2 Here, infection remains relatively high, with a substantial proportion of districts with . 15% prevalence of chlamydial infection.…”

“…The first describes Amhara, the most severely affected region in Ethiopia. 2 Amhara is unique in that the trachoma program monitors not only clinical activity as required by WHO guidelines, but also conjunctival chlamydial infection, the cause of trachoma. The second publication reports the association of clinical trachoma with water, sanitation, and hygiene (WASH) indicators in an area of southern Ethiopia.…”

“…The first report highlights considerable progress against trachoma in western Amhara. 2 Although sampling was sparse, 40% (62 of 156) of districts surveyed had no evidence of current infection. Interestingly, the majority of these districts with no evidence of infection still had not achieved control per the WHO guidelines.…”