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Table 1 Summary of the trachoma indicators, methodology, and sample size

From: Impact of a single round of mass drug administration with azithromycin on active trachoma and ocular Chlamydia trachomatis prevalence and circulating strains in The Gambia and Senegal

Trachoma indicator Methodology Sample size (children aged 0–9 years) Total
The Gambia Senegal
Baseline (March–May 2006) One year follow-up (June–July 2007) Baseline (January–February 2007) One year follow-up (March–May 2008)
Children aged 0–9 years examined for active trachoma (TF and/or TI) WHO simplified grading system [27] 1171 1171 1613 1771 5726
Ocular C. trachomatis infection Amplicor PCR (Roche Molecular Systems) 1171 1171 1613 1771 5726
Organism load of Amplicor-positives ompA copy number estimates using two real-time quantitative PCR assays for genovars A and B separately [29] 35 45 29 64 173
Multi-locus sequence typing (MLST) Determination of sequences at the five loci: hctB, CT058, CT144, CT172, pbpB [22, 23] 13 18 13 29 73
ompA sequencing Sequences aligned against reference sequences from A/HAR 13 (NC_007429, genovar A) and B/Jali20/OT (NC_012686, genovar B), with alignments trimmed at the ends until high quality (Q20) base-calls were present at all positions 19 21 16 38 94
MLST6 The five MLST regions combined with ompA 14 18 12 28 72
Whole-genome sequencing (WGS) Set of 71 WGS from the Bijagos Islands with inferred MLST and ompA types [40] na na na na 71
  1. Abbreviations: na, not applicable;TF, trachomatous inflammation-follicular; TI, trachomatous inflammation-intense; PCR, polymerase chain reaction