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

Abstract

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. 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). 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 (PChlamydia trachomatis as part of the surgery, antibiotic, facial cleanliness, and environmental improvement (SAFE) strategy. After approximately 5 years of SAFE in Amhara region, Ethiopia, however, many districts remained hyperendemic as measured by observed clinical signs. Given the persistent nature of trachoma in Amhara, a better understanding of the nature of actual Chlamydia trachomatis infection, including the distribution of infectious load within children, would be helpful for Amhara and for programs serving other hyperendemic regions. From 2011 to 2015 nearly 7,500 ocular swabs from 4 endemic zones were collected to monitor Chlamydia trachomatis following 5 years of SAFE among children aged 1 to 5 years, the group most at risk for infection. It was determined that pre-school age children still harbored considerable infection. The youngest children had the highest infection prevalence and highest infectious load burden, and therefore likely contributed in meaningful ways towards the persistent active trachoma observed in some districts. Treatment regimens focused on the youngest children or children harboring the highest infectious loads should be explored to help countries experiencing persistent trachoma reach elimination as a public health problem faster.