Comparison of platforms for testing antibodies to Chlamydia trachomatis antigens in the Democratic Republic of the Congo and Togo

Gwyn, Sarah; Awoussi, Marcel S; Bakhtiari, Ana; Bronzan, Rachel N.; Crowley, Kathryn; Harding-Esch, Emma; Kassankogno, Y; Kilangalanga, Janvier; Makangila, Felix; Mupoyi, Sylvain; Ngondi, Jeremiah; Ngoyi, Bonaventure Fuamba; Palmer, Stephanie L.; Randall, J; Seim, Anders; Solomon, Anthony W.; Stewart, R. L.; Togbey, Kwamy; Uvon, Pitchouna A; Martin, Diana L.

doi:10.1038/s41598-021-86639-8

Cited by 8 publications

(11 citation statements)

References 25 publications

(23 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Agdez, which also had low TF prevalence, had antibody prevalence of 12% and a SCR of around 2–3, both higher than expected based on models derived data from multiple sites for which the predicted Ab prevalence was 6.5% and SCR of 1.5 corresponding to TF of < 5%. 25 It is important to note that these are preliminary threshold estimates and that these data from Morocco and other more recent studies 16 , 17 , 29 will be used to enhance and improve these models. However, it is worth trying to understand why such high levels of antibody positivity were seen in Agdez.…”

Section: Discussionmentioning

confidence: 99%

“…The prevalence of antibodies to the C. trachomatis antigens Pgp3 and CT694 12 – 14 increase with age in children living in trachoma-endemic communities, 14 , 15 but not in areas of low or no transmission. 16 – 18 Antibodies could therefore be used to differentiate high-prevalence settings for trachoma, in which children are repeatedly infected with ocular C. trachomatis throughout childhood, compared with low-prevalence settings for trachoma in which children might only be infected once or a few times during childhood. These data are consistent when using different testing platforms.…”

Section: Introductionmentioning

confidence: 99%

“…These data are consistent when using different testing platforms. 16 , 19 Further research is required to refine interpretation and guide the potential application of data on antibodies to C. trachomatis in programmatic decision-making.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Post-Validation Survey in Two Districts of Morocco after the Elimination of Trachoma as a Public Health Problem

Hammou

Guagliardo

Obtel

et al. 2022

The American Journal of Tropical Medicine and Hygiene

Self Cite

View full text Add to dashboard Cite

Trachoma is the leading infectious cause of blindness. In 2016, Morocco was validated by WHO as having eliminated trachoma as a public health problem. We evaluated two previously endemic districts in Morocco for trachomatous inflammation—follicular (TF), trachomatous trichiasis (TT), and antibodies against Chlamydia trachomatis, the causative agent of trachoma. Community-based cross-sectional surveys in the districts of Boumalene Dades and Agdez included 4,445 participants for whom both questionnaire and serology data were available; 58% were aged 1–9 years. Participants had eyes examined for TF and blood collected for analysis of antibodies to the C. trachomatis antigen Pgp3 by both a multiplex bead assay (MBA) and lateral flow assay (LFA). Seroconversion rates (SCR) per 100 people per year were used to estimate changes in the force of infection using Bayesian serocatalytic models. In Agdez, TF prevalence in 1–9-year-olds was 0.3%, seroprevalence ranged from 9.4% to 11.4%, and SCR estimates ranged from 2.4 to 3.0. In Boumalene Dades, TF prevalence in 1–9-year-olds was 0.07%, and modeling data from the different assays indicated a decrease in transmission between 20 and 24 years ago. The TF data support an absence of active trachoma in the two districts examined. However, seroprevalence and SCR in younger people were higher in Agdez than Boumalene Dades, showing that there can be differences in serology metrics in areas with similar TF prevalence. Data will be included in multicountry analyses to better understand potential thresholds for serological surveillance in trachoma.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Post-Validation Survey in Two Districts of Morocco after the Elimination of Trachoma as a Public Health Problem

Hammou

Guagliardo

Obtel

et al. 2022

The American Journal of Tropical Medicine and Hygiene

Self Cite

View full text Add to dashboard Cite

show abstract

“…Dried blood spots were tested by a lateral flow dipstick assay with a colloidal gold detecting reagent conjugated to Pgp3 (LFA-gold; Abcam, Cambridge, United Kingdom) and a black latex detecting reagent conjugated to Pgp3 (LFA-latex; Abcam) as described. 10 , 14 All samples tested on LFA-latex and samples from Alefa tested on LFA-gold were read by two readers to assess inter-rater agreement.…”

Section: Methodsmentioning

confidence: 99%

“… 11 The LFA has undergone several iterations, starting out in a cassette for use in house-to-house surveys, 10 , 12 moving to laboratory-based “dipstick” format, 13 the most recent version using a black latex detector to improve readability. 14 Each time a new version is developed, testing must be performed to ensure results are consistent between platforms.…”

Section: Introductionmentioning

confidence: 99%

The Performance of Immunoassays to Measure Antibodies to the Chlamydia trachomatis Antigen Pgp3 in Different Epidemiological Settings for Trachoma

Gwyn

Nute

Sata

et al. 2021

The American Journal of Tropical Medicine and Hygiene

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Effect of Biannual Mass Azithromycin Distributions to Preschool-Aged Children on Trachoma Prevalence in Niger

et al. 2022

Self Cite

View full text Add to dashboard Cite

IMPORTANCEBecause transmission of ocular strains of Chlamydia trachomatis is greatest among preschool-aged children, limiting azithromycin distributions to this age group may conserve resources and result in less antimicrobial resistance, which is a potential advantage in areas with hypoendemic trachoma and limited resources. OBJECTIVE To determine the efficacy of mass azithromycin distributions to preschool-aged children as a strategy for trachoma elimination in areas with hypoendemic disease. DESIGN, SETTING, AND PARTICIPANTS In this cluster randomized clinical trial performed from November 23, 2014, until July 31, 2017, thirty rural communities in Niger were randomized at a 1:1 ratio to biannual mass distributions of either azithromycin or placebo to children aged 1 to 59 months. Participants and study personnel were masked to treatment allocation. Data analyses for trachoma outcomes were performed from October 19, 2021, through June 10, 2022. INTERVENTIONS Every 6 months, a single dose of either oral azithromycin (20 mg/kg using heightbased approximation for children who could stand or weight calculation for small children) or oral placebo was provided to all children aged 1 to 59 months. MAIN OUTCOMES AND MEASURES Trachoma was a prespecified outcome of the trial, assessed as the community-level prevalence of trachomatous inflammation-follicular and trachomatous inflammation-intense through masked grading of conjunctival photographs from a random sample of 40 children per community each year during the 2-year study period. A secondary outcome was the seroprevalence of antibodies to C trachomatis antigens. RESULTS At baseline, 4726 children in 30 communities were included; 1695 children were enrolled in 15 azithromycin communities and 3031 children were enrolled in 15 placebo communities (mean [SD] proportions of boys, 51.8% [4.7%] vs 52.0% [4.2%]; mean [SD] age, 30.8 [2.8] vs 30.6 [2.6]months). The mean coverage of study drug for the 4 treatments was 79% (95% CI, 75%-83%) in the azithromycin group and 82% (95% CI, 79%-85%) in the placebo group. The mean prevalence of trachomatous inflammation-follicular at baseline was 1.9% (95% CI, 0.5%-3.5%) in the azithromycin group and 0.9% (95% CI, 0-1.9%) in the placebo group. At 24 months, trachomatous inflammation-follicular prevalence was 0.2% (95% CI, 0-0.5%) in the azithromycin group and 0.8% (95% CI, 0.2%-1.6%) in the placebo group (incidence rate ratio adjusted for baseline: 0.18 [95% CI, 0.01-1.20]; permutation P = .07).

show abstract

Comparison of platforms for testing antibodies to Chlamydia trachomatis antigens in the Democratic Republic of the Congo and Togo

Cited by 8 publications

References 25 publications

Post-Validation Survey in Two Districts of Morocco after the Elimination of Trachoma as a Public Health Problem

Post-Validation Survey in Two Districts of Morocco after the Elimination of Trachoma as a Public Health Problem

The Performance of Immunoassays to Measure Antibodies to the Chlamydia trachomatis Antigen Pgp3 in Different Epidemiological Settings for Trachoma

Effect of Biannual Mass Azithromycin Distributions to Preschool-Aged Children on Trachoma Prevalence in Niger

Contact Info

Product

Resources

About