Investigator(s)
| WHO Technical Officer |
Mokryeon Cho WHO Timor Leste Mokryeon Cho 
|
| Principal Investigator |
Joao Soares Martins Universidade Nacional Timor-Lorosa’e Joao Soares Martins
|
| Co-Investigator(s) |
Hanna Jin Seoul National University, WHO Timor Leste Hanna Jin
|
Title(s) and abstract
| Scientific title | Integrated Cross-sectional Survey of Trachoma and Yaws Seroprevalence in Pre-school Children and Soil-transmitted Helminth Infections in School-aged Children in Timor-Leste |
| Public title | Integrated NTD surveys for trachoma, yaws and soil-transmitted helminths in Timor-Leste |
| Background | Timor-Leste has entered the post-zero case surveillance phase for yaws elimination, marking progress toward the 2023 target in the National Strategic Plan for NTDs (2021-2025). Since 2019, an integrated yaws surveillance system has reported 574 suspected cases, but all tested negative. WHO recommends serosurveys to confirm transmission interruption, requiring three surveys over ten years. Trachoma surveillance remains part of NTD monitoring, though studies since 2018 have found no active cases or trichiasis. Soil-transmitted helminths (STH) remain a public health concern, with past surveys showing high prevalence—over 50% in Dili and 29.1% nationally (2012). Mass drug administration (MDA) from 2015 to 2019 reduced STH prevalence to 17.9% (2020), but COVID-19 disrupted deworming efforts. School-based deworming resumed in 2022, yet recent studies show moderate-to-heavy infections, highlighting the need for updated data. This study will assess NTD prevalence across Timor-Leste’s 14 municipalities to guide evidence-based policies and targeted interventions. |
| Objectives | • To determine the current status of trachoma transmission in Timor-Leste through serological surveillance of antibody responses in children aged 1-5 years across all municipalities • To verify the interruption of yaws transmission by assessing whether the prevalence of latent yaws cases remains below the WHO-specified threshold (< 1%) through serological testing, supporting Timor-Leste's elimination goals • To establish the current prevalence and intensity of STH infections among primary school-aged children (6-14 years) following the resumption of deworming activities post-COVID-19 • To analyze the epidemiological profile of STH infections, including: - Species-specific prevalence rates - Distribution of infection intensities - Geographic patterns of infection across municipalities - Risk factors associated with persistent transmission |
| Study Methods | This comprehensive survey in Timor-Leste aims to assess three neglected tropical diseases across all 14 municipalities through two main study components. The first component focuses on trachoma and yaws surveillance, targeting 5,485 children aged 1-5 years across 150 aldeias (sub-villages) using two-stage cluster random sampling with compact segment sampling, collecting dried blood spots via finger prick for serological testing using multiplex bead assay. The country has been divided into five evaluation units of 250,000-350,000 people each to facilitate efficient data collection and analysis. The second component examines soil-transmitted helminth infections among 1,960 primary school children aged 6-14 years across 28 schools (one sentinel and one spot-check school per municipality), achieving 90.8% statistical power within a 5% margin of error, with stool samples analyzed using the Kato-Katz (KK) technique. The implementation involves 292 staff members for the community survey and 60 team members for the school survey, with data management utilizing Kobo Toolbox for electronic entry, Excel for validation, and Stata/IC 15.1 for statistical analysis, while also incorporating WASH assessments, risk factor questionnaires, and quality control measures including double-reading of slides and preservation of KK positive stool specimens for molecular analysis. |
| Expected outcomes and use of results | STHs prevalence: target prevalence < 10% in all selected schools M&HI across the municipalities < 2% Trachoma prevalence Yaws prevalence: < 1% |
| Keywords | sth, trachoma, yaws, NTD, infection, Timor Leste, prevalence |
Research Details
| Student research | No |
| Start Date | 25-Feb-2025 |
| End Date | 30-Jun-2025 |
| Key Implementing Institution | World Health Organization |
| Multi-country research | No |
| Nationwide research | Yes |
| Research Domain(s) | Communicable Disease Research |
| Research field(s) | Infectious Disease |
| Involves human subjects | Yes |
| Population-Based Survey | |
| Data Collection | Primary data |
| Proposal reviewed by other Committee | Final decision available |