Serology reflects a decline in the prevalence of trachoma in two regions of The Gambia

Abstract

Trachoma is caused by Chlamydia trachomatis (Ct). It is targeted for global elimination as a public health problem. In 2014, a population-based cross-sectional study was performed in two previously trachoma-endemic areas of The Gambia. Participants of all ages from Lower River Region (LRR) (N = 1028) and Upper River Region (URR) (N = 840) underwent examination for trachoma and had blood collected for detection of antibodies against the Ct antigen Pgp3, by ELISA. Overall, 30 (1.6%) individuals had active trachoma; the prevalence in children aged 1–9 years was 3.4% (25/742) with no statistically significant difference in prevalence between the regions. There was a significant difference in overall seroprevalence by region: 26.2% in LRR and 17.1% in URR (p<0.0001). In children 1-9 years old, seroprevalence was 4.4% in LRR and 3.9% in URR. Reversible catalytic models using information on age-specific seroprevalence demonstrated a decrease in the transmission of Ct infection in both regions, possibly reflecting the impact of improved access to water, health and sanitation as well as mass drug administration campaigns. Serological testing for antibodies to Ct antigens is potentially useful for trachoma programmes, but consideration should be given to the coendemicity of sexually transmitted Ct infections.

Predicting future ocular Chlamydia trachomatis infection prevalence using serological, clinical, molecular, and geospatial data

“…Our investigation builds upon an existing body of work characterizing the dynamics between clinical, serological, and molecular trachoma indicators. Reports at the district, village, and individual level have established that relatively high levels of clinical trachoma or ocular infections tend to correspond to higher seroprevalence and/or seroconversion rates (14, 28-31); post-elimination settings have been of particular interest, with populations often displaying little to no antibody response (15,(32)(33)(34)(35)(36)(37). Our findings align with earlier studies that showed clinical trachoma is more strongly correlated with infection prevalence in populations with ongoing transmission compared to populations in which transmission has been suppressed by MDA (38)(39)(40); also in agreement with prior findings, we observed that TI was slightly, but not significantly, more closely correlated with infection prevalence compared to TF immediately following MDA (Figure S10) (41).…”

No Serological Evidence of Trachoma or Yaws Among Residents of Registered Camps and Makeshift Settlements in Cox’s Bazar, Bangladesh

“…Serologic testing for antibody responses against C. trachomatis antigens is gaining traction as a potential approach for conducting surveillance in areas that have achieved elimination criteria for trachoma and ceased interventions. Seroprevalence of anti-C. trachomatis antibodies typically increases with age among 1to 9-year-olds in areas with ongoing transmission [10][11][12] but remain relatively flat, with low seroconversion rates, 13 in the absence of transmission [14][15][16] and in settings where the presence of TF does not correlate with ocular C. trachomatis infection. 17,18 Serologic testing is standard for yaws diagnosis: the T. pallidum particle agglutination (TPPA) assay reflects a history of T. pallidum infection, whereas nontreponemal tests such as rapid plasmin reagin (RPR) detect antibodies against host molecules released in response to infection, giving an indication of current or recent exposure.…”