Reduction and Return of Infectious Trachoma in Severely Affected Communities in Ethiopia

Abstract

BackgroundAntibiotics are a major tool in the WHO's trachoma control program. Even a single mass distribution reduces the prevalence of the ocular chlamydia that causes trachoma. Unfortunately, infection returns after a single treatment, at least in severely affected areas. Here, we test whether additional scheduled treatments further reduce infection, and whether infection returns after distributions are discontinued.MethodsSixteen communities in Ethiopia were randomly selected. Ocular chlamydial infection in 1- to 5-year-old children was monitored over four biannual azithromycin distributions and for 24 months after the last treatment.FindingsThe average prevalence of infection in 1- to 5-year-old children was reduced from 63.5% pre-treatment to 11.5% six months after the first distribution (P<0.0001). It further decreased to 2.6% six months after the fourth and final treatment (P = 0.0004). In the next 18 months, infection returned to 25.2%, a significant increase from six months after the last treatment (P = 0.008), but still far lower than baseline (P<0.0001). Although the prevalence of infection in any particular village fluctuated, the mean prevalence of the 16 villages steadily decreased with each treatment and steadily returned after treatments were discontinued.ConclusionIn some of the most severely affected communities ever studied, we demonstrate that repeated mass oral azithromycin distributions progressively reduce ocular chlamydial infection in a community, as long as these distributions are given frequently enough and at a high enough coverage. However, infection returns into the communities after the last treatment. Sustainable changes or complete local elimination of infection will be necessary.Trial RegistrationClinicalTrials.gov NCT00221364

Association of Conjunctival Bacterial Infection and Female Sex in Cicatricial Trachoma

“…The study area was hyperendemic for trachoma, with estimates of prevalent ocular chlamydial infection as high as 63.5% among 1-to 5-year-old children. 12 Villages were randomly selected from a sample of 24 villages that were being monitored as part of a clinical trial for trachoma (ClinicalTrials.gov number NCT00221364). Villages came from different treatment arms of the trial, but were similar in that none of the villages had received mass azithromycin within the preceding 6 months.…”

Clinical Activity and Polymerase Chain Reaction Evidence of Chlamydial Infection after Repeated Mass Antibiotic Treatments for Trachoma

“…Sixteen study villages were randomly selected from the Enemore district of the Gurage Zone, and received biannual treatment for two years (at months 0, 6,12,18). Eight study villages randomly selected from the adjacent district of Goro received biannual treatment for three years (at months 0, 6,12,18,24,30). During a mass treatment, all eligible members of the village were offered single dose, directly observed oral azithromycin (1 g for adults and 20 mg/kg for children ≥ 1 year of age).…”

Estimating Community Prevalence of OcularChlamydia trachomatisInfection using Pooled Polymerase Chain Reaction Testing

“…12,13 The clinical trial was described in depth previously and registered with clinicaltrials.gov (NCT00221364). Simulations were based on data from the collected specimens, which were performed according to the guidelines of the Declaration of Helsinki.…”

“…We determined the bias, ðP À PÞ, of the estimated numberP of infected individuals, using simulations Estimating Prevalence using Pooled Specimens 87 for communities of size 49-200 and pools of size 2, 3, and 5 (typical pool sizes used in previous studies; 12,13,16,17 for convenience, we did not consider pools of size 4). Specifically, we assumed a true number of positive infections, and simulated the possible assignments of the positives over a given set of pool sizes.…”