Abstract
ABSTRACT.Programs to eliminate trachoma as a public health problem use prevalence of the clinical sign trachomatous inflammation—follicular (TF) in 1- to 9-year-olds in endemic districts to make decisions to begin or end mass drug administration with azithromycin. Trachomatous inflammation—follicular is used as a proxy for transmission of ocular Chlamydia trachomatis infection. Long-term monitoring of previously endemic districts for recrudescence of ocular C. trachomatis infection would benefit from a simple blood test that could be integrated with other public health programs. In this study, we evaluated multiple tests to measure antibodies against the C. trachomatis antigen Pgp3—a multiplex bead assay (MBA), an ELISA, and two versions of a lateral flow assay (LFA)—in four districts of the Amhara region of Ethiopia with varying levels of TF. Seroprevalence and seroconversion rate (SCR) results were proportional to TF prevalence by district for most tests, with the notable exception of the LFA using colloidal gold as the developing reagent. Changing the test developing reagent to black latex improved agreement between serological measures and TF prevalence and in inter-rater agreement. Seroconversion rate estimates using data derived from the LFA-gold assay were inconsistent with the shape of the age-seroprevalence curve, which did not increase in older ages. These data revealed potential complications with using SCR that will need further evaluation. Data from MBA, ELISA, and LFA with the black test line showed good agreement with each other and proportionality to TF estimates, providing further data that serology has potential utility for trachoma surveillance.
Highlights
Trachoma, the leading infectious cause of blindness, is an eye disease caused by repeated ocular infection with the bacterium Chlamydia trachomatis (Ct) and is targeted for elimination as a public health problem (EPHP).[1]
Long-term monitoring of previously endemic districts for recrudescence of ocular C. trachomatis infection would benefit from a simple blood test that could be integrated with other public health programs
We evaluated multiple tests to measure antibodies against the C. trachomatis antigen Pgp3—a multiplex bead assay (MBA), an ELISA, and two versions of a lateral flow assay (LFA)—in four districts of the Amhara region of Ethiopia with varying levels of trachomatous inflammation—follicular (TF)
Summary
The leading infectious cause of blindness, is an eye disease caused by repeated ocular infection with the bacterium Chlamydia trachomatis (Ct) and is targeted for elimination as a public health problem (EPHP).[1]. Tools to monitor for recrudescence of infection will be essential upon cessation of interventions once countries achieve EPHP targets.[2]. Antibodies against Ct antigens show potential as a surveillance tool in postelimination settings.[2,3,4,5] not diagnostic of infection in an individual, the presence of antibodies indicates exposure to Ct and can show transmission trends in a community.[6] It is still unclear how serological results should be used to detect potential recrudescence of infection. More data are needed from a variety of epidemiological settings to understand the relationship between TF, SCR, and seroprevalence, and to define appropriate seropositivity thresholds for programs to maintain EPHP.[2] Preliminary models suggest that a mean seroprevalence of less than 6.2% and a seroconversion rate (SCR) of below 0.015 seroconversion events per year in 1- to 9-year-olds correspond to a TF of less than 5%.7 More data are needed from a variety of epidemiological settings to understand the relationship between TF, SCR, and seroprevalence, and to define appropriate seropositivity thresholds for programs to maintain EPHP.[2]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
