title: Comparison of annual and biannual mass antibiotic administration for elimination of infectious trachoma.
abstract: BACKGROUND
  Treatment recommendations assume that repeated mass antibiotic distributions can control, but not eradicate or even locally eliminate, the ocular strains of chlamydia that cause trachoma. Elimination may be an important end point because of concern that infection will return to communities that have lost immunity to chlamydia after antibiotics are discontinued.
  
  
  OBJECTIVE
  To determine whether biannual treatment can eliminate ocular chlamydial infection from preschool children and to compare results with the World Health Organization-recommended annual treatment.
  
  
  METHODS
  A cluster-randomized clinical trial of biannual vs annual mass azithromycin administrations to all residents of 16 rural villages in the Gurage Zone, Ethiopia, from March 2003 to April 2005.
  
  
  METHODS
  At scheduled treatments, all individuals aged 1 year or older were offered a single dose of oral azithromycin either annually or biannually.
  
  
  METHODS
  Village prevalence of ocular chlamydial infection and presence of elimination at 24 months in preschool children determined by polymerase chain reaction, correcting for baseline prevalence. Antibiotic treatments were performed after sample collections.
  
  
  RESULTS
  Overall, 14,897 of 16,403 eligible individuals (90.8%) received their scheduled treatment. In the villages in which residents were treated annually, the prevalence of infection in preschool children was reduced from a mean of 42.6% (range, 14.7%-56.4%) to 6.8% (range, 0.0%-22.0%) at 24 months. In the villages in which residents were treated biannually, infection was reduced from 31.6% pretreatment (range, 6.1%-48.6%) to 0.9% (range, 0.0%-4.8%) at 24 months. Biannual treatment was associated with a lower prevalence at 24 months (P = .03, adjusting for baseline prevalence). At 24 months, no infection could be identified in 6 of 8 of those treated biannually and in 1 of 8 of those treated annually (P = .049, adjusting for baseline prevalence).
  
  
  CONCLUSIONS
  Local elimination of ocular chlamydial infection appears feasible even in the most severely affected areas, although it may require biannual mass antibiotic distributions at a high coverage level.
  
  
  BACKGROUND
  clinicaltrials.gov Identifier: NCT00221364.
authors.affiliation: Orbis International, Addis Ababa, Ethiopia.
authors.forename: Muluken
authors.initials: M
authors.lastname: Melese
authors.forename: Wondu
authors.initials: W
authors.lastname: Alemayehu
authors.forename: Takele
authors.initials: T
authors.lastname: Lakew
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Yi
authors.forename: Jenafir
authors.initials: J
authors.lastname: House
authors.forename: Jaya D
authors.initials: JD
authors.lastname: Chidambaram
authors.forename: Zhaoxia
authors.initials: Z
authors.lastname: Zhou
authors.forename: Vicky
authors.initials: V
authors.lastname: Cevallos
authors.forename: Kathryn
authors.initials: K
authors.lastname: Ray
authors.forename: Kevin Cyrus
authors.initials: KC
authors.lastname: Hong
authors.forename: Travis C
authors.initials: TC
authors.lastname: Porco
authors.forename: Isabella
authors.initials: I
authors.lastname: Phan
authors.forename: Ali
authors.initials: A
authors.lastname: Zaidi
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Gaynor
authors.forename: John P
authors.initials: JP
authors.lastname: Whitcher
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Lietman
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D017963:Azithromycin / Q000008:administration & dosage* / Q000627:therapeutic use; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D014141:Trachoma / Q000188:drug therapy*
chemical_list: D000900:Anti-Bacterial Agents; D017963:Azithromycin