title: 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.
abstract: BACKGROUND
  The 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.
  
  
  METHODS
  20 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.
  
  
  RESULTS
  3 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.
  
  
  CONCLUSIONS
  The 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.
authors.affiliation: Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Andrea I
authors.initials: AI
authors.lastname: Zambrano
authors.affiliation: National Trachoma Program, Nepal Netra Jyoti Sangh (NNJS), Kathmandu, Nepal.
authors.forename: Shekhar
authors.initials: S
authors.lastname: Sharma
authors.affiliation: RTI International, Washington, DC, United States of America.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Crowley
authors.affiliation: International Chlamydia Laboratory, Johns Hopkins Hospital, Baltimore, Maryland, United States of America.
authors.forename: Laura
authors.initials: L
authors.lastname: Dize
authors.affiliation: Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Beatriz E
authors.initials: BE
authors.lastname: Muñoz
authors.affiliation: National Trachoma Program, Nepal Netra Jyoti Sangh (NNJS), Kathmandu, Nepal.
authors.forename: Sailesh K
authors.initials: SK
authors.lastname: Mishra
authors.affiliation: RTI International, Washington, DC, United States of America.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Rotondo
authors.affiliation: International Chlamydia Laboratory, Johns Hopkins Hospital, Baltimore, Maryland, United States of America.
authors.forename: Charlotte A
authors.initials: CA
authors.lastname: Gaydos
authors.affiliation: Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Sheila K
authors.initials: SK
authors.lastname: West