Date Published: January 06, 2018
Publisher: The American Society of Tropical Medicine and Hygiene
Author(s): Sarah E. Gwyn, Lingwei Xiang, Ram Prasad Kandel, Deborah Dean, Manoj Gambhir, Diana L. Martin.
The target end date for the global elimination of trachoma as a public health problem is 2020. As countries begin the process for submitting their dossier for the validation of elimination of trachoma as a public health problem, strategies for post-validation surveillance must be considered. Seroprevalence of antibodies against antigens from the causative bacteria Chlamydia trachomatis (Ct) in young children has been shown to reflect trachomatous inflammation–follicular (TF) rates in both endemic and previously endemic settings. However, none of these studies has directly compared age seroprevalence in the same communities before and after mass drug administration (MDA) for trachoma. Here we report a marked shift in age seroprevalence curves in four villages in Kapilvastu District, Nepal, before and after MDA. Clinical examinations were performed and blood was taken before (N = 659) and 5 years after (N = 646) MDA. Rates of TF decreased from 17.6% in ≤ 9-year-olds before MDA (N = 52) to 0% in ≤ 9-year-olds (N = 73) after MDA. Positive antibody responses to Ct in the entire population decreased from 82.1% pre-MDA to 35.8% post-MDA, whereas those among ≤ 9-year-olds decreased from 59.6% to 4.1%. These data show that the postintervention decrease in TF was reflected in a drop in anti-Ct antibody responses, suggesting that antibody responses could be useful indicators for post-validation surveillance.
Trachoma is caused by repeated ocular infection with Chlamydia trachomatis (Ct) and is the leading infectious cause of blindness in the world today. Over 200 million people are at risk of infection with an estimated 1.9 million people blind or visually impaired due to trachoma (www.trachomacoalition.org/GET2020). Efforts by the World Health Organization (WHO) and other partners are underway to eliminate trachoma as a public health problem by 2020 through implementation of the SAFE strategy: surgery to correct trichiasis (one or more eyelashes rubbing against the globe of the eye), mass drug administration (MDA) of antibiotics for all individuals living in endemic districts, facial cleanliness, and environmental improvement. The Nepali Government Trachoma Program has conducted annual MDA with azithromycin and offered surgery to correct trichiasis in trachoma-endemic regions of Nepal. The MDA program commenced in 2007 and most of the villagers received MDA each year for 3 years.
The data presented here show marked shifts in the Ct-specific age–seroprevalence curve in trachoma-endemic communities before and after cessation of MDA. Rates of TF in ≤ 9-year-olds dropped from 17.6% before MDA to 0% after MDA in these communities.