title: Re-emergence of Chlamydia trachomatis infection after mass antibiotic treatment of a trachoma-endemic Gambian community: a longitudinal study.
abstract: BACKGROUND
  Community-wide mass antibiotic treatment is a central component of trachoma control. The optimum frequency and duration of treatment are unknown. We measured the effect of mass treatment on the conjunctival burden of Chlamydia trachomatis in a Gambian community with low to medium trachoma prevalence and investigated the rate, route, and determinants of re-emergent infection.
  
  
  METHODS
  14 trachoma-endemic villages in rural Gambia were examined and conjunctival swabs obtained at baseline, 2, 6, 12, and 17 months. Mass antibiotic treatment with azithromycin was given to the community at baseline. C trachomatis was detected by qualitative PCR and individual infection load then estimated by real-time quantitative PCR.
  
  
  RESULTS
  C trachomatis was detected in 95 (7%) of 1319 individuals at baseline. Treatment coverage was 83% of the population (1328 of 1595 people). The effect of mass treatment was heterogeneous. In 12 villages all baseline infections (34 [3%] of 1062 individuals) resolved, and prevalence (three [0.3%]) and infection load remained low throughout the study. Two villages (baseline infection: 61 [24%] of 257 individuals) had increased infection 2 months after treatment (74 [30%]), after extensive contact with other untreated communities. Subsequently, this value reduced to less than half of that before treatment (25 [11%]).
  
  
  CONCLUSIONS
  Mass antibiotic treatment generally results in effective, longlasting control of C trachomatis in this environment. For low prevalence regions, one treatment episode might be sufficient. Infection can be reintroduced through contact with untreated populations. Communities need to be monitored for treatment failure and control measures implemented over wide geographical areas.
authors.affiliation: London School of Hygiene and Tropical Medicine, London, UK. matthew.burton@lshtm.ac.uk
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Burton
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Holland
authors.forename: Pateh
authors.initials: P
authors.lastname: Makalo
authors.forename: Esther A N
authors.initials: EA
authors.lastname: Aryee
authors.forename: Neal D E
authors.initials: ND
authors.lastname: Alexander
authors.forename: Ansumana
authors.initials: A
authors.lastname: Sillah
authors.forename: Hannah
authors.initials: H
authors.lastname: Faal
authors.forename: Sheila K
authors.initials: SK
authors.lastname: West
authors.forename: Allen
authors.initials: A
authors.lastname: Foster
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Johnson
authors.forename: David C W
authors.initials: DC
authors.lastname: Mabey
authors.forename: Robin L
authors.initials: RL
authors.lastname: Bailey
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D017963:Azithromycin / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D002692:Chlamydia trachomatis; D019353:Endemic Diseases; D005260:Female; D005714:Gambia / Q000453:epidemiology; D006801:Humans; D007223:Infant; D008297:Male; D015995:Prevalence; D014141:Trachoma / Q000188:drug therapy* / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission
chemical_list: D000900:Anti-Bacterial Agents; D017963:Azithromycin