The World Health Organization Recommendations for Trachoma Surveillance, Experience in Nepal and Added Benefit of Testing for Antibodies to Chlamydia trachomatis pgp3 Protein: NESTS Study.

Andrea I Zambrano,Beatriz E Muñoz,Charlotte A Gaydos,Shekhar Sharma,Laura Dize,Sheila K West,Sailesh K Mishra,Kathryn Crowley,Lisa A Rotondo,Thomas M Lietman

doi:10.1371/journal.pntd.0005003

Andrea I Zambrano, Beatriz E Muñoz + Show 8 more

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https://doi.org/10.1371/journal.pntd.0005003

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Abstract

BackgroundThe World Health Organization (WHO) now requires a second surveillance survey for trachoma after an impact assessment has found follicular trachoma (TF) <5% to determine if re-emergence has occurred. Using new WHO guidelines, we undertook surveillance surveys, and determined the prevalence of infection and antibody positivity, in two districts in Nepal.Methods20 clusters were randomly selected within each district, 15 were randomly selected for antibody testing. In each cluster, we randomly selected 50 children ages 1–9 years and 100 adults ≥15 years. TF and trachomatous trichiasis (TT) were evaluated. Conjunctival swabs to test for chlamydial infection using GenXpert platform were obtained, and dried blood spots were collected to test for antibodies to Chlamydia Trachomatis pgp3 using the Luminex platform.Findings3 cases of TF were found in the two districts, and one case of infection. Pgp3 antibody positivity was 2·4% (95% confidence interval: 1·4%, 3·7%), and did not increase with age (P = 0.24). No clustering of antibody positivity within communities was found. TT prevalence was <1/1,000 population.InterpretationThe surveillance surveys, as proposed by WHO, showed no evidence for re-emergence of trachoma in two districts of Nepal. The low level and no significant increase by age in seroprevalence of antibodies to C trachomatis pgp3 antigen deserve further investigation as a marker of interruption of transmission.

Highlights

Trachoma, a chronic conjunctivitis caused by repeated episodes of Chlamydia trachomatis, is still the leading infectious cause of blindness worldwide[1]
Once districts have shown that the prevalence of follicular trachoma (TF) in children ages 1–9 years is below 5%, they must monitor for re-emergence
The World Health Organization (WHO) recommends a second surveillance or “pre-validation” survey to determine if re-emergence has occurred

Summary

Introduction

A chronic conjunctivitis caused by repeated episodes of Chlamydia trachomatis, is still the leading infectious cause of blindness worldwide[1]. The World Health Organization (WHO) recommends a multi-faceted strategy, the SAFE strategy, for trachoma control (SAFE is Surgery for trichiasis, Antibiotics to reduce infection, Facial hygiene, and Environmental change for sustainable interruption of transmission)[1,2,3]. Country programs are encouraged to map suspected trachoma endemic districts to determine the prevalence of follicular trachoma (TF) and trichiasis (TT), and institute SAFE where trachoma is more than 5% in children ages 1–9 years and TT is 1/1,000 total population or more[1,2,3,4]. To ensure longer term, sustainable, achievement of goals, post-MDA surveillance in formerly endemic districts should be carried out. The World Health Organization (WHO) requires a second surveillance survey for trachoma after an impact assessment has found follicular trachoma (TF)

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