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. 2020 Apr;80(4):454-461.
doi: 10.1016/j.jinf.2020.01.015. Epub 2020 Feb 1.

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

Affiliations

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

Robert Butcher et al. J Infect. 2020 Apr.

Abstract

Introduction: In the peri-elimination setting, the positive predictive value of trachomatous inflammation-follicular (TF), the primary marker used to determine need for antibiotics for trachoma, is suboptimal. Here, three non-TF measures are used to compare two regions where TF prevalence exceeds the threshold for intervention, but where the Chlamydia trachomatis (Ct) prevalence is different.

Methods: Population prevalence of trachoma was measured in Vanuatu (n = 3470) and Kiribati (n = 2922). Dried blood spots (DBS) and conjunctival photographs were collected from every survey participant, and conjunctival swabs were collected from those aged 1-9 years. Individuals were tested for blood anti-Pgp3 antibodies, Ct DNA at the conjunctiva and severity of conjunctival scarring.

Results: The prevalence of TF in 1-9-year-olds was 16.5% in Vanuatu and 38.2% in Tarawa. 7% of people aged ≥1 year in Vanuatu had conjunctival scarring compared to 27% in Tarawa. The prevalence of ocular Ct infection in 1-9-year-olds was 1.5% in Vanuatu and 27.4% in Tarawa. The seroconversion rate amongst 1-9-year-old children in Vanuatu and Tarawa was 0.018 and 0.197 events per child per year, respectively.

Conclusions: Comparing Vanuatu to Tarawa demonstrates several markers that could be used to differentiate the trachoma status of populations in these (and other) locations.

Keywords: Anti-Pgp3 antibodies; Chlamydia trachomatis; Kiribati; Neglected tropical diseases; Trachoma; Vanuatu.

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Conflict of interest statement

Declaration of Competing Interest None of the authors declare any conflicts of interest.

Figures

Fig. 1
Fig. 1
(A) Location of evaluation units surveyed in 2016. (B) Cluster locations (red dots) in Vanuatu. (C) Cluster locations (red dots) in Tarawa, Kiribati. Shapefiles obtained from Database of Global Administrative Areas (www.gadm.org).
Fig. 2
Fig. 2
Age-specific prevalence of conjunctival scar grade in (A) Vanuatu (n = 1871) and (B) Tarawa, Kiribati (n = 1891). Group sizes are displayed above each bar. C0: No scarring on the conjunctiva (not shown); C1: Mild: Fine, scattered scars on the upper tarsal conjunctiva or scars on other parts of the conjunctiva; C2: Moderate: more severe scarring, but without shortening or distortion of the upper tarsus; C3: Severe: Scarring with distortion of the upper tarsus.
Fig. 3
Fig. 3
Upper panels show age-specific anti-Pgp3 seroprevalence in children aged 1–9 years in (A) Vanuatu (n = 1084) and (B) Tarawa, Kiribati (n = 1015). Lower panels show age-specific anti-Pgp3 seroprevalence in people of all ages in (C) Vanuatu (n = 3401) and (D) Tarawa, Kiribati (n = 2805). Samples collected June–September 2016. Red whiskers indicate 95% confidence intervals.

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