Dataset Information

Monitoring transmission intensity of trachoma with serology.

ABSTRACT: Trachoma, caused by ocular Chlamydia trachomatis infection, is targeted for global elimination as a public health problem by 2030. To provide evidence for use of antibodies to monitor C. trachomatis transmission, we collated IgG responses to Pgp3 antigen, PCR positivity, and clinical observations from 19,811 children aged 1- 9 years in 14 populations. We demonstrate that age-seroprevalence curves consistently shift along a gradient of transmission intensity: rising steeply in populations with high levels of infection and active trachoma and becoming flat in populations near elimination. Seroprevalence (range: 0-54%) and seroconversion rates (range: 0-15 per 100 person-years) correlate with PCR prevalence (r: 0.87, 95% CI: 0.57, 0.97). A seroprevalence threshold of 13.5% (seroconversion rate 2.75 per 100 person-years) identifies clusters with any PCR-identified infection at high sensitivity (>90%) and moderate specificity (69-75%). Antibody responses in young children provide a robust, generalizable approach to monitor population progress toward and beyond trachoma elimination.

SUBMITTER: Tedijanto C

PROVIDER: S-EPMC9949201 | biostudies-literature | 2023 May

REPOSITORIES: biostudies-literature

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Monitoring transmission intensity of trachoma with serology.

Tedijanto Christine C Solomon Anthony W AW Martin Diana L DL Nash Scott D SD Keenan Jeremy D JD Lietman Thomas M TM Lammie Patrick J PJ Aiemjoy Kristen K Amza Abdou A Aragie Solomon S Arzika Ahmed M AM Callahan E Kelly EK Carolan Sydney S Dawed Adisu Abebe AA Goodhew E Brook EB Gwyn Sarah S Hammou Jaouad J Kadri Boubacar B Kalua Khumbo K Maliki Ramatou R Nassirou Beido B Seife Fikre F Tadesse Zerihun Z West Sheila K SK Wittberg Dionna M DM Zeru Taye T Arnold Benjamin F BF

medRxiv : the preprint server for health sciences 20230517

Trachoma, caused by ocular <i>Chlamydia trachomatis</i> infection, is targeted for global elimination as a public health problem by 2030. To provide evidence for use of antibodies to monitor <i>C. trachomatis</i> transmission, we collated IgG responses to Pgp3 antigen, PCR positivity, and clinical observations from 19,811 children aged 1- 9 years in 14 populations. We demonstrate that age-seroprevalence curves consistently shift along a gradient of transmission intensity: rising steeply in popul ...[more]

PMID: 36824972

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Project description:BackgroundTrachoma, caused by Chlamydia trachomatis (Ct), is the leading infectious cause of blindness worldwide. Yearly azithromycin mass drug administration (MDA) plays a central role in efforts to eliminate blinding trachoma as a public health problem. Programmatic decision-making is currently based on the prevalence of the clinical sign "trachomatous inflammation-follicular" (TF) in children. We sought to test alternative tools for trachoma surveillance based on serology in the 12-year cohort of Kahe Mpya, Rombo District, Tanzania, where ocular chlamydial infection was eliminated with azithromycin MDA by 2005.Methodology and principal findingsThe present study was a community-based cross-sectional survey in Kahe Mpya. Of 989 residents, 571 people aged 6 months to 87 years were enrolled: 58% of the total population and 73% of 1-9 year olds, the key WHO indicator age group. Participants were examined for TF, had conjunctival swabs collected for nucleic acid amplification test (NAAT)-based detection of Ct, and blood collected for analysis of antibodies to the Ct antigens pgp3 and CT694 by multiplex bead-based immunoassay. Seroconversion rate was used to estimate changes in the force of infection in a reversible catalytic model. No conjunctival swabs tested positive for Ct infection by NAAT. Among 1-9 year olds, TF prevalence was 6.5%, whereas only 3.5% were seropositive. Force of infection modelling indicated a 10-fold decrease in seroconversion rate at a time corresponding to MDA commencement. Without baseline serological data, the inferences we can make about antibody status before MDA and the longevity of the antibody response are limited, though our use of catalytic modelling overcomes some of these limitations.Conclusions/significanceSerologic tests support NAAT findings of very low to zero prevalence of ocular Ct in this community and have potential to provide objective measures of transmission and useful surveillance tools for trachoma elimination programs.

Project description:BackgroundTo eliminate trachoma as a public health problem, countries must achieve a district-level prevalence of trachomatous inflammation-follicular (TF) <5% in children ages 1-9 years. Re-emergence of TF could trigger additional rounds of mass drug/antibiotic administration (MDA), so accurate tools for use in surveys assessing trachoma prevalence are essential.Methodology & principal findingsWe surveyed 2401 children ages 1-9 years from 50 villages in Kongwa, Tanzania, 2 years post-MDA and 1.5 years after an impact survey found TF <5% in the same villages. Our survey included multiple tools: clinical determination of TF, Cepheid testing for Chlamydia trachomatis infection, and testing for anti-pgp3 antibodies via multiplex bead array. Photographs of the upper tarsal conjunctiva were taken in a subset of children to corroborate the field grades. Overall TF prevalence in 1-9 year olds was 7.1% (95% CI: 5.6%-8.9%), which decreased with age (p = <0.0001). TF prevalence by village was heterogeneous, with 19 villages having TF <5% and 16 villages having TF >10%. There was a strong correlation between field and photo grading of TF (kappa = 0.69; 95% CI: 0.60-0.78) and between TF and infection, with 21.5% of TF-positive children also testing positive for infection, as compared to only 1.6% of TF-negative children (p = 0.0010). Overall seroprevalence was 18.2% (95% CI: 14.8%-22.1%), which increased with age (p = <0.0001). Notably, 1-2 year olds, who were born after the cessation of MDA and theoretically should not have had exposure to C. trachomatis in the absence of transmission, had an average seroprevalence of 6.7%.Conclusions & significanceField TF prevalence, supported by photographic review and infection data, suggested re-emergence of trachoma in Kongwa. Moreover, seropositivity in the children born after cessation of MDA indicated exposure to C. trachomatis despite a previous survey finding of TF <5%. Examining seropositivity in specific age groups expected to have limited exposure to C. trachomatis can be used to detect re-emergence.

Dataset Information

Monitoring transmission intensity of trachoma with serology.

Publications

Monitoring transmission intensity of trachoma with serology.

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