Impact of two rounds of azithromycin mass drug administration on active trachoma and ocular Chlamydia trachomatis infection in Naoero
9 affiliations
- 1The Kirby Institute, UNSW, Sydney, Australia
- 2Ministry of Health and Medical Services, Denig, Naoero
- 3Pacific Eye Care Society, Suva, Fiji
- 4NSW State Reference Laboratory for HIV, St Vincent’s Centre for Applied Medical Research, St Vincent’s Hospital, Sydney, Australia
- 5London School of Hygiene & Tropical Medicine, London, United Kingdom
- 6Sightsavers, Haywards Heath, United Kingdom
- 7International Trachoma Initiative, The Task Force for Global Health, Decatur, Georgia, United States of America
- 8Malaria & Neglected Tropical Diseases Department, World Health Organization, Geneva, Switzerland
- 9School of Public Health, University of Queensland, Herston, Australia
Abstract
Background: Trachoma, caused by ocular infection with the bacterium Chlamydia trachomatis, is the primary infectious cause of blindness globally. To contribute to the elimination of trachoma as a public health problem, Naoero undertook two rounds of antibiotic mass drug administration (MDA) using azithromycin, with population-level coverage estimated at 87% and 93%. This study aimed to estimate the post-MDA prevalence of trachoma, and infection with C. trachomatis, in children aged 1–9 years. Methods: A two-stage cluster sampled survey was conducted 12 months after the second MDA round. All residents aged ≥1 year were examined for signs of trachoma, and conjunctival swabs were collected from children aged 1–9 years for PCR testing. Data on domestic access to water, sanitation, and hygiene services were also collected. Results: Overall, 2,150 residents were examined, with 724 aged 1–9 years. The age-adjusted prevalence of trachomatous inflammation—follicular (TF) in children aged 1–9 years was 6.0% (95%CI 3.9–7.7). The age-adjusted prevalence of C. trachomatis in the same age group was 2.7% (95%CI 0.3–5.1). There was evidence of trachomatous trichiasis (TT) previously unknown to the health system in one resident aged ≥15 years out of 1114 examined (age- and gender-adjusted prevalence 0.04%, 95%CI 0–0.12). Access to improved water sources for hygiene purposes was reported in 99.8% of households surveyed, and 99% of households reported access to an improved latrine. Conclusions: In Naoero, the impact survey prevalence of TF was above, and of TT was below, the thresholds defined by WHO as indicating “elimination as a public health problem”. The C. trachomatis prevalence estimate was lower than it was pre-MDA (39.4%), demonstrating the impact of antibiotic MDA. Despite the potential value of PCR data in addition to clinical indicators to help inform the need for trachoma elimination interventions, particularly in post-MDA or low TF prevalence areas, standardised thresholds for interpreting C. trachomatis prevalence have yet to be established. They are urgently needed so that they can be formally used to guide future interventions. Author summary: This study looked at the clinical signs of trachoma, the world’s leading infectious cause of blindness, as well as biological evidence of current bacterial Chlamydia trachomatis infection, in children in Naoero. The data were collected after two rounds of mass drug administration (MDA) of azithromycin for trachoma. We show that trachoma and C. trachomatis prevalence declined post antibiotic treatment, however, trachoma prevalence continues to fulfil the definition of trachoma as a public health problem, suggesting that public health interventions, including MDA with antibiotics and ongoing health promotion and environmental health improvements are required. As global efforts to eliminate trachoma continue, this survey demonstrates that integrating biological analysis into population-based surveys is both feasible and valuable for informing programme decision-making, although internatioally agreed thresholds for interpreting C. trachomatis are needed.
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BibTeX
@article{cowling2026impact,
title = {{Impact of two rounds of azithromycin mass drug administration on active trachoma and ocular Chlamydia trachomatis infection in Naoero}},
author = {Carleigh S. Cowling and Sue-Chen Apadinuwe and Anasaini Cama and Mitchell Starr and Emma M. Harding-Esch and Cristina Jimenez and Ana Bakhtiari and Sarah Boyd and Sara Webster and Anthony W. Solomon and Simon Reid and John M. Kaldor and Susana Vaz Nery},
journal = {PLOS Neglected Tropical Diseases},
year = {2026},
month = sep,
doi = {10.1371/journal.pntd.0014679},
url = {https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014679},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Impact of two rounds of azithromycin mass drug administration on active trachoma and ocular Chlamydia trachomatis infection in Naoero
AU - Carleigh S. Cowling
AU - Sue-Chen Apadinuwe
AU - Anasaini Cama
AU - Mitchell Starr
AU - Emma M. Harding-Esch
AU - Cristina Jimenez
AU - Ana Bakhtiari
AU - Sarah Boyd
AU - Sara Webster
AU - Anthony W. Solomon
AU - Simon Reid
AU - John M. Kaldor
AU - Susana Vaz Nery
PY - 2026
DA - 2026/09/16
JO - PLOS Neglected Tropical Diseases
DO - 10.1371/journal.pntd.0014679
UR - https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014679
AB - Background: Trachoma, caused by ocular infection with the bacterium Chlamydia trachomatis, is the primary infectious cause of blindness globally. To contribute to the elimination of trachoma as a public health problem, Naoero undertook two rounds of antibiotic mass drug administration (MDA) using azithromycin, with population-level coverage estimated at 87% and 93%. This study aimed to estimate the post-MDA prevalence of trachoma, and infection with C. trachomatis, in children aged 1–9 years. Methods: A two-stage cluster sampled survey was conducted 12 months after the second MDA round. All residents aged ≥1 year were examined for signs of trachoma, and conjunctival swabs were collected from children aged 1–9 years for PCR testing. Data on domestic access to water, sanitation, and hygiene services were also collected. Results: Overall, 2,150 residents were examined, with 724 aged 1–9 years. The age-adjusted prevalence of trachomatous inflammation—follicular (TF) in children aged 1–9 years was 6.0% (95%CI 3.9–7.7). The age-adjusted prevalence of C. trachomatis in the same age group was 2.7% (95%CI 0.3–5.1). There was evidence of trachomatous trichiasis (TT) previously unknown to the health system in one resident aged ≥15 years out of 1114 examined (age- and gender-adjusted prevalence 0.04%, 95%CI 0–0.12). Access to improved water sources for hygiene purposes was reported in 99.8% of households surveyed, and 99% of households reported access to an improved latrine. Conclusions: In Naoero, the impact survey prevalence of TF was above, and of TT was below, the thresholds defined by WHO as indicating “elimination as a public health problem”. The C. trachomatis prevalence estimate was lower than it was pre-MDA (39.4%), demonstrating the impact of antibiotic MDA. Despite the potential value of PCR data in addition to clinical indicators to help inform the need for trachoma elimination interventions, particularly in post-MDA or low TF prevalence areas, standardised thresholds for interpreting C. trachomatis prevalence have yet to be established. They are urgently needed so that they can be formally used to guide future interventions. Author summary: This study looked at the clinical signs of trachoma, the world’s leading infectious cause of blindness, as well as biological evidence of current bacterial Chlamydia trachomatis infection, in children in Naoero. The data were collected after two rounds of mass drug administration (MDA) of azithromycin for trachoma. We show that trachoma and C. trachomatis prevalence declined post antibiotic treatment, however, trachoma prevalence continues to fulfil the definition of trachoma as a public health problem, suggesting that public health interventions, including MDA with antibiotics and ongoing health promotion and environmental health improvements are required. As global efforts to eliminate trachoma continue, this survey demonstrates that integrating biological analysis into population-based surveys is both feasible and valuable for informing programme decision-making, although internatioally agreed thresholds for interpreting C. trachomatis are needed.
SN - 1935-2735
ER -