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 co-endemicity of sexually transmitted Ct infections.

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

“…33 These data align with survey-based trachoma antibody data from other lowprevalence or post-endemic settings. 5,6,30,[34][35][36][37] For example, a recent report of surveillance surveys, conducted in six Ghanaian districts with low TF, demonstrated a district range of Pgp3 prevalence between 2.5% and 8.2% and 1.3 seroconversions per 100 children per year. 37 In addition, Pgp3 and CT694 seroprevalence did not increase with age in Woreta town, nor did CT694 seroprevalence increase with age in Alefa, a finding which has been observed in other post-endemic settings.…”

“…Antibody responses to C. trachomatis antigens have recently been used to measure the cumulative exposure to the bacterium among trachoma-affected or previously affected populations. 5,6 In particular, antibodies against the C. trachomatis antigens Pgp3 and CT694 have been shown to be present in those infected with C. trachomatis, to increase with age in trachoma-endemic populations, and to be at low prevalence in populations receiving MDA with antibiotics. 5,[7][8][9][10] However, the programmatic role of these markers in trachoma control is still being determined.…”

Household Survey of Trachoma Among Children Living in Pernambuco, Brazil

“…Moreover, with little water available, hygiene actions are less frequent. Studies in Gambia [45] and Ethiopia [46] demonstrated that there was a reduction in the transmission of C. trachomatis infection with improved sanitation and water access.…”

Impact Survey Results after SAFE Strategy Implementation in 15 Local Government Areas of Kebbi, Sokoto and Zamfara States, Nigeria

“…50 Implementation of azithromycin MDA, even though irregular, combined with education on the need for personal and environmental hygiene, likely contributed to declines in TF prevalence. Reduced TF prevalence is associated with a reduction in the reservoir of ocular C. trachomatis, so this is expected to be accompanied by decreased community transmission intensity 51 and, ultimately, a fall in the incidence of TT. 52 We are, however, unable to confidently credit apparent falls in TF prevalence (Table 3) to implementation of the A, F and E components of the SAFE strategy.…”