Abstract
PurposeTo examine the relationship between ocular Chlamydia trachomatis infection and follicular trachoma (TF) in children prior to and following multiple rounds of annual mass drug administration (MDA) with azithromycin.Methodology/principal findingsThirty-two communities with endemic trachoma in Kongwa District, Tanzania, were offered annual MDA as part of a district-wide trachoma control program. Presence of ocular C. trachomatis infection and TF were assessed in 3,200 randomly sampled children aged five years and younger, who were examined prior to each MDA. Infection was detected using the Amplicor CT/NG assay and TF was identified by clinical examination using the World Health Organization (WHO) simplified grading system. The association between chlamydial infection and TF in children was evaluated at baseline prior to any treatment, and 12 months after each of three annual rounds of mass treatment. Factors associated with infection were examined using generalized estimating equation models.At baseline, the overall prevalence of chlamydial infection and TF was 22% and 31%, respectively. Among children with clinical signs of TF, the proportion of those with infection was 49% prior to treatment and declined to 30% after three MDAs. The odds of infection positivity among children with clinical signs of TF decreased by 26% (OR 0.74, 95% CI 0.65 to 0.84, p = <0.01) with each MDA, after adjusting for age. For children aged under one year, who did not receive treatment, the relationship was unchanged.Conclusions/significanceThe association between ocular C. trachomatis infection and TF weakened in children with each MDA, as both infection and clinical disease prevalence declined. However, there was still a significant proportion of TF cases with infection after three rounds of MDA. New strategies are needed to assess this residual infection for optimal treatment distribution.
Highlights
Trachoma, the most common preventable cause of blindness in the world [1,2], is caused by repeated and/or prolonged episodes of ocular infection by the bacterium Chlamydia trachomatis
As part of a randomized community trial, we evaluated ocular chlamydial infection and TF in communities located in the Kongwa District of Tanzania, where the prevalence of active trachoma ranged from 20% to 50% prior to any treatment [9,10]
There was an average of 1,457 residents in each of the 32 communities included in the study (Table 1)
Summary
The most common preventable cause of blindness in the world [1,2], is caused by repeated and/or prolonged episodes of ocular infection by the bacterium Chlamydia trachomatis. The disease disproportionately affects individuals living in rural and resource-poor settings, and children are the primary carriers of ocular C. trachomatis infection and active disease [3]. Trachoma control programs rely on a package of interventions developed by the World Health Organization (WHO) that comprises Surgery for trichiasis, Antibiotics for reducing infection, Facial cleanliness, and Environmental improvement, which is referred to as the SAFE strategy [7,8]. Annual mass drug administration (MDA) with single-dose azithromycin is recommended for trachoma control in communities in which the prevalence of follicular trachoma (TF) is 10% or greater in children aged 1–9 years, with the aim of reducing TF prevalence to under 5% [8]. At least three years of MDA are recommended before reassessing the need for further MDA; monitoring the impact of antibiotic intervention, which targets C. trachomatis, Author Summary
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