A-Z Index × Submit A-Z Index × Submit A-Z Index Search Dropdown × Submit Facebook Twitter LinkedIn Syndicate Emerging Infectious Disease journal ISSN: 1080-6059 Disclaimer: Early release articles are not considered as final versions. Any changes will be reflected in the online version in the month the article is officially released.
We evaluated the probability of needing public health actions against trachoma in Esmeraldas Province, Ecuador, by estimating seroconversion rates of Chlamydia trachomatis plasma gene protein 3 IgG in children. Seroconversion rates suggest high probability of the need for public health interventions in rural communities and motivate further assessment.
Trachoma is a blinding eye disease caused by infection with ocular strains of Chlamydia trachomatis ; trachoma has been declared a public health concern by the World Health Organization and targeted for elimination by 2030 ( 1 ). Public health interventions for trachoma include surgery for trichiasis, mass administration of antimicrobial drugs, and programs to support facial cleanliness and environmental improvement ( 2 ).
IgGs against the plasma gene protein 3 (Pgp3) of C. trachomatis are sensitive markers of past infections, making them suitable for monitoring populations after mass administration of antimicrobial drugs ( 3 ). Pgp3 antibodies can be used to measure trachoma transmission intensity in population-based surveys ( 4 ). A global analysis of trachoma was used to develop methods that use the Pgp3 IgG seroconversion rate (SCR) to estimate the probability of needing public health actions ( 5 ).
The highest prevalence of trachoma is found in sub-Saharan Africa ( 2 ). Trachoma also remains a public health concern in remote areas of South America; elimination efforts by the Pan American Health Organization are ongoing ( 6 ). Little is known about trachoma in Ecuador. We recently identified high levels of incident seroconversion of Pgp3 antibodies within a birth cohort in Esmeraldas Province of coastal Ecuador (L. Simbaña et al., unpub. data, https://doi.org/10.64898/2026.02.16.26346420 ). Here, we describe augmenting those birth cohort samples by including samples from older children living in villages within the same region and estimated Pgp3 antibody SCRs. We compared those data with global SCR distributions to estimate the probability of needing public health actions against trachoma.
We included samples from 2 studies. The ECoMiD longitudinal birth cohort study in Esmeraldas Province enrolled pregnant mothers during 2019–2022 along an urban–rural gradient that included Esmeraldas city (urban), Borbón (commercial center for the region), 4 communities accessible by road, and 4 communities accessible via the Santiago and Onzole Rivers ( Appendix Figure) ( 7 ). Dried blood spots were collected during 2021–2024, when children were 6, 9, 12, 18, and 24 months of age (L. Simbaña et al., unpub. data). We also included serum samples collected from community-based, annual serologic surveillance of arbovirus transmission in Borbón; 5 other communities, 4 of which overlapped with the ECoMiD study areas (Maldonado, Colon Eloy, Timbiré, Santo Domingo); and Santa Maria, along the Cayapas River ( 8 ). Annual surveys were conducted during August–October and used age-stratified sampling, which oversampled 2–14-year-old children.
We tested samples from 2–15-year-old children collected during the 2021 and 2022 surveys for Pgp3 IgG by using the Luminex platform ( h…