<i>Chlamydia trachomatis</i> strains identified in this study.

<p>Only single nucleotide polymorphisms and their locations are shown. Reference strains are <i>C. trachomatis</i> HAR 13 (genovar A) (NC_007429) and <i>C. trachomatis</i> M33636 (genovar B). Letters in parenthesis represent the amino acid and any resulting change. Genotype B2 is identical to the reference strain. (VS, variable sequence. CS, conserved sequence.)</p

Comparative ocular <i>C. trachomatis</i> infection status (by Amplicor) before and two months after antibiotic treatment amongst all those tested at both time points.

<p>(+ infected, − not infected).</p

Clinical activity, infection (Amplicor) and genotypes by village and timepoint.

<p>For each village, ‘Examined’ is the number of people examined ‘TF/TI’ is the number of individuals (all ages) with active trachoma, and ‘CT+’ the number of those whose ocular swabs tested positive by Amplicor. The numbers bracketed after the genotype indicate the number of times it appeared: A2 (14) denotes 14 samples contained genotype A2.</p

Frequency of <i>C. trachomatis</i> strains present at baseline and 2 months, subdivided by site of collection. Numbers in parenthesis are %.

<p>Frequency of <i>C. trachomatis</i> strains present at baseline and 2 months, subdivided by site of collection. Numbers in parenthesis are %.</p

Comparison of the most recent prevalence estimates for trachomatous inflammation—Follicular (TF) in 1–9-year-olds, Malawi, in (a) 2014 and (b) 2016 (after the impact surveys reported here, undertaken following one round of azithromycin MDA).

<p>Comparison of the most recent prevalence estimates for trachomatous inflammation—Follicular (TF) in 1–9-year-olds, Malawi, in (a) 2014 and (b) 2016 (after the impact surveys reported here, undertaken following one round of azithromycin MDA).</p

Trachomatous inflammation—Follicular (TF) prevalence at baseline and at impact survey, selected districts, Malawi, 2013–2016.

<p>Trachomatous inflammation—Follicular (TF) prevalence at baseline and at impact survey, selected districts, Malawi, 2013–2016.</p

Evaluation unit population sizes, number of 1–9-year-old children examined, and trachomatous inflammation—Follicular (TF) prevalence in 1–9-year-olds, impact surveys, Malawi, May–August 2016.

<p>Evaluation unit population sizes, number of 1–9-year-old children examined, and trachomatous inflammation—Follicular (TF) prevalence in 1–9-year-olds, impact surveys, Malawi, May–August 2016.</p

One round of azithromycin MDA adequate to interrupt transmission in districts with prevalence of trachomatous inflammation—follicular of 5.0-9.9%: Evidence from Malawi

<div><p>Background</p><p>As highly trachoma-endemic countries approach elimination, some districts will have prevalences of trachomatous inflammation–follicular in 1–9-year-olds (TF_1-9) of 5.0–9.9%. The World Health Organization (WHO) previously recommended that in such districts, TF prevalence be assessed in each sub-district (groupings of at least three villages), with three rounds of azithromycin treatment offered to any sub-district in which TF≥10%. Given the large number of endemic districts worldwide and the human and financial resources required to conduct surveys, this recommendation may not be practical. In a group of 8 Malawi districts with baseline TF prevalences of 5.0–9.9%, the Malawi Ministry of Health administered one round of azithromycin mass treatment, to the whole of each district, achieving mean coverage of ~80%. Here, we report impact surveys conducted after that treatment.</p><p>Methods</p><p>We undertook population-based trachoma surveys in 18 evaluation units of the 8 treated districts, at least 6 months after the MDA. The standardized training package and survey methodologies of Tropical Data, which conform to WHO recommendations, were used.</p><p>Results</p><p>Each of the 18 evaluation units had a TF_1-9 prevalence <5.0%.</p><p>Conclusion</p><p>The study demonstrates that in Malawi districts with TF of 5.0–9.9%, one round of azithromycin MDA with ~80% coverage associates with a reduction in TF prevalence to <5%. Further evidence for this approach should be collected elsewhere.</p></div

Prevalence of TF in children aged 1 to 9 years by surveillance zone in years 2011 to 2013.

<p>Prevalence of TF in children aged 1 to 9 years by surveillance zone in years 2011 to 2013.</p

Map of The Gambia indicating the boundaries of the trachoma surveillance zones.

<p>Map of The Gambia indicating the boundaries of the trachoma surveillance zones.</p