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. 2022 Apr 19;16(4):e0010275.
doi: 10.1371/journal.pntd.0010275. eCollection 2022 Apr.

A national survey integrating clinical, laboratory, and WASH data to determine the typology of trachoma in Nauru

Kathleen D Lynch  1 , Sue Chen Apadinuwe  2 , Stephen B Lambert  1   3 , Tessa Hillgrove  4 , Mitchell Starr  5 , Beth Catlett  5 , Robert S Ware  6 , Anasaini Cama  4 , Sara Webster  4 , Emma M Harding-Esch  7 , Ana Bakhtiari  8 , Robert Butcher  7 , Philip Cunningham  5 , Diana Martin  9 , Sarah Gwyn  9 , Anthony W Solomon  10 , Chandalene Garabwan  2 , John M Kaldor  11 , Susana Vaz Nery  11
Affiliations

A national survey integrating clinical, laboratory, and WASH data to determine the typology of trachoma in Nauru

Kathleen D Lynch et al. PLoS Negl Trop Dis. .

Abstract

Background: The epidemiology of trachoma in several Pacific Islands differs from other endemic settings, in that there is a high prevalence of clinical signs of trachoma, particularly trachomatous inflammation-follicular (TF), but few cases of trichiasis and limited evidence of ocular chlamydial infection. This so-called "Pacific enigma" has led to uncertainty regarding the appropriate public health response. In 2019 alongside Nauru's national trachoma population survey, we performed bacteriological and serological assessments of children to better understand the typology of trachoma and to determine whether there is a need for trachoma interventions.

Methods: We used two-stage cluster sampling, examining residents aged ≥1 year and collecting household-level water, sanitation, and hygiene (WASH) variables. Children aged 1-9 years provided conjunctival swabs and finger-prick dried blood spots to investigate the presence of Chlamydia trachomatis nucleic acid and anti-Pgp3 antibodies, respectively.

Principal findings: In 818 participants aged 1-9 years, the age-adjusted TF prevalence was 21.8% (95% CI 15.2-26.2%); ocular C. trachomatis prevalence was 34.5% (95% CI 30.6-38.9), and anti-Pgp3 antibody prevalence was 32.1% (95% CI 28.4%-36.3%). The age- and gender-adjusted prevalence of trichiasis in ≥15-year-olds was 0.3% (95% CI 0.00-0.85), but no individual with trichiasis had trachomatous scarring (TS). Multivariable analysis showed an association between age and both TF (OR per year of age 1.3 [95% CI 1.2-1.4]) and anti-Pgp3 positivity (OR 1.2 [95% CI 1.2-1.3]). There were high rates of access to water and sanitation and no WASH variable was associated with the presence of TF.

Conclusions: TF, nucleic acid, and age-specific antibody prevalence collectively indicate that high levels of C. trachomatis transmission among children present a high risk of ocular damage due to trachoma. The absence of trichiasis with trachomatous scarring suggest a relatively recent increase in transmission intensity.

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Conflict of interest statement

I have read the journal’s policy and the authors of this manuscript have the following competing interests: AB is employed by the International Trachoma Initiative at The Task Force for Global Health, which receives an operating budget and research funds from Pfizer Inc., the manufacturers of Zithromax (azithromycin). EMHE receives salary support from the International Trachoma Initiative.

Figures

Fig 1
Fig 1. Recruitment and results flow diagram, Nauru, July 2019.
Abbreviations: TF, trachomatous inflammation—follicular; TI, trachomatous inflammation—intense; TS, trachomatous scarring; PCR Ct, polymerase chain reaction Chlamydia trachomatis; ELISA, enzyme-linked immunosorbent assay; +ve, positive; -ve, negative. *This is a slight underestimation due to inconsistent recording of absenteeism in the first week of the survey. During this first week, 16% (124/764) of people were recorded as absent vs 27% (733/2707) across the remaining 3 weeks of the survey. Extrapolating the average level of absenteeism over the last three weeks to the first week, we expect an additional 82 individuals were absent.
Fig 2
Fig 2. Prevalence of trachomatous inflammation—follicular, ocular Chlamydia trachomatis detection, and anti-Pgp3 antibodies in examined children aged 1–9 years in Nauru, July 2019.
Abbreviations: TF, trachomatous inflammation—follicular. Error bars showing 95% confidence intervals around survey prevalence estimate for each outcome.
Fig 3
Fig 3. Co-occurrence of clinical and laboratory findings in children aged 1–9 years in Nauru, July 2019.
Abbreviations: TF, trachomatous inflammation—follicular; ELISA, enzyme-linked immunosorbent assay; PCR, polymerase chain reaction.
See this image and copyright information in PMC

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