The Relationship between Active Trachoma and Ocular Chlamydia trachomatis Infection before and after Mass Antibiotic Treatment

Abstract

BackgroundTrachoma is a blinding disease, initiated in early childhood by repeated conjunctival infection with the obligate intracellular bacterium Chlamydia trachomatis. The population prevalence of the clinical signs of active trachoma; ‘‘follicular conjunctivitis” (TF) and/or ‘‘intense papillary inflammation” (TI), guide programmatic decisions regarding the initiation and cessation of mass drug administration (MDA). However, the persistence of TF following resolution of infection at both the individual and population level raises concerns over the suitability of this clinical sign as a marker for C. trachomatis infection.Methodology/Principle FindingsWe systematically reviewed the literature for population-based studies and those including randomly selected individuals, which reported the prevalence of the clinical signs of active trachoma and ocular C. trachomatis infection by nucleic acid amplification test. We performed a meta-analysis to assess the relationship between active trachoma and C. trachomatis infection before and after MDA. TF and C. trachomatis infection were strongly correlated prior to MDA (r = 0.92, 95%CI 0.83 to 0.96, p<0.0001); the relationship was similar when the analysis was limited to children. A moderate correlation was found between TI and prevalence of infection. Following MDA, the relationship between TF and infection prevalence was weaker (r = 0.60, 95%CI 0.25 to 0.81, p = 0.003) and there was no correlation between TI and C. trachomatis infection.Conclusions/SignificancePrior to MDA, TF is a good indicator of the community prevalence of C. trachomatis infection. Following MDA, the prevalence of TF tends to overestimate the underlying infection prevalence. In order to prevent unnecessary additional rounds of MDA and to accurately ascertain when elimination goals have been reached, a cost-effective test for C. trachomatis that can be administered in low-resource settings remains desirable.

Impact of a single round of mass drug administration with azithromycin on active trachoma and ocular Chlamydia trachomatis prevalence and circulating strains in The Gambia and Senegal

“…The WHO active trachoma indicator for programmatic decisions regarding MDA initiation and duration is the prevalence of TF in children aged 1-9 years. TF was a poor predictor for infection, but infection was a fairly reliable indicator for having TF, consistent with others' findings in low prevalence or mass treated settings [7,15,44,[54][55][56][57][58][59][60][61]. Furthermore, our data indicate that the assertion by others that inclusion of TI would improve the association between clinical signs and infection [62] is likely context-specific.…”

Ocular Chlamydia trachomatis infection, anti-Pgp3 antibodies and conjunctival scarring in Vanuatu and Tarawa, Kiribati before antibiotic treatment for trachoma

“…The relationship between TF and ocular Ct infection in Tarawa resembles trachoma-endemic districts in sub-Saharan Africa. 34 In contrast, the relationship between ocular Ct infection and TF in Vanuatu resembles findings from neighbouring Solomon Islands and Papua New Guinea, 17 , 35 with the ocular Ct infection prevalence being considerably lower than the prevalence of TF. Notably, the absence of association between TF and anti-Pgp3 antibody in Vanuatu suggests that TF there may have an alternative, non-chlamydial cause.…”

Comparison of Face Washing and Face Wiping Methods for Trachoma Control: A Pilot Study

“…These results are consistent with other published studies. 10 The main limitations of this study were the small sample size, the nonrandom allocation of protocols, and the nonblinded nature of the intervention for researchers. The design was pragmatic, but might have introduced bias in terms of classifying the presence of discharge or consistency of the procedures (albeit we had clear standard operating procedures and training).…”