Baseline trachoma prevalence in Guinea: Results of national trachoma mapping in 31 health districts

<div><p>Background</p><p>Based on previous studies, historical records and risk factors, trachoma was suspected to be endemic in 31 health districts (HDs) in Guinea. To facilitate planning for the elimination of trachoma as a public health problem, national trachoma surveys were conducted between 2011 and 2016 to determine the prevalence of trachomatous inflammation—follicular (TF) and trachomatous trichiasis (TT) in all 31 endemic HDs.</p><p>Methodology/Principal findings</p><p>A total of 27 cross-sectional surveys were conducted, each using two-stage cluster sampling (one survey in 2011 covered five HDs). Children aged 1–9 years and adults aged ≥15 years were examined for TF and TT, respectively, using the World Health Organization (WHO) simplified grading system. Indicators of household access to water, sanitation and hygiene (WASH) were also collected. A total of 100,051 people from 13,725 households of 556 clusters were examined, of whom 44,899 were male and 55,152 were female. 44,209 children aged 1–9-years and 48,745 adults aged ≥15 years were examined. The adjusted prevalence of TF varied between 1.0% (95%CI: 0.6–1.5%) to 41.8% (95%CI: 39.4–44.2%), while the adjusted prevalence of TT ranged from 0.0% (95%CI: 0.0–0.2%) to 2.8% (95%CI: 2.3–3.5%) in the 27 surveys. In all, 18 HDs had a TF prevalence ≥5% in children aged 1–9 years and 21 HDs had a TT prevalence ≥0.2% in adults aged ≥15 years. There were an estimated 32,737 (95% CI: 19,986–57,811) individuals with TT living in surveyed HDs at the time of surveys.</p><p>Conclusions/Significance</p><p>Trachoma is a public health problem in Guinea. 18 HDs required intervention with at least one round of mass drug administration and an estimated 32,737 persons required TT surgery in the country. The results provided clear evidence for Guinea to plan for national trachoma elimination.</p></div

Adjusted prevalence of TF, TT and estimated TT cases in Guinea.

<p>Adjusted prevalence of TF, TT and estimated TT cases in Guinea.</p

Key indicators on access to water, sanitation and hygiene (WASH) by district in Guinea.

<p>Key indicators on access to water, sanitation and hygiene (WASH) by district in Guinea.</p

Health district TF endemicity categories and cluster-level distribution in Guinea.

<p>GPS coordinate information was missing for 24 clusters from the 2011–13 surveys and these clusters are not shown in the map. Figure was created for this publication using shapefiles from the GADM database (<a href="http://www.gadm.org/" target="_blank">www.gadm.org</a>), version 2.8, November 2015 and ArcGIS 10.4.1 for Desktop (ESRI, Redlands, CA).</p

Characteristics of surveyed population by evaluation unit in Guinea.

<p>Characteristics of surveyed population by evaluation unit in Guinea.</p

Health district TT prevalence categories and cases in Guinea.

<p>Numeric numbers represent the estimated number of TT cases in population aged ≥15 years in each HD. Figure was created for this publication using shapefiles from the GADM database (<a href="http://www.gadm.org/" target="_blank">www.gadm.org</a>), version 2.8, November 2015 and ArcGIS 10.4.1 for Desktop (ESRI, Redlands, CA).</p

Tropical Data: Approach and Methodology as Applied to Trachoma Prevalence Surveys

Population-based prevalence surveys are essential for decision-making on interventions to achieve trachoma elimination as a public health problem. This paper outlines the methodologies of Tropical Data, which supports work to undertake those surveys. Tropical Data is a consortium of partners that supports health ministries worldwide to conduct globally standardised prevalence surveys that conform to World Health Organization recommendations. Founding principles are health ministry ownership, partnership and collaboration, and quality assurance and quality control at every step of the survey process. Support covers survey planning, survey design, training, electronic data collection and fieldwork, and data management, analysis and dissemination. Methods are adapted to meet local context and needs. Customisations, operational research and integration of other diseases into routine trachoma surveys have also been supported. Between 29th February 2016 and 24th April 2023, 3373 trachoma surveys across 50 countries have been supported, resulting in 10,818,502 people being examined for trachoma. This health ministry-led, standardised approach, with support from the start to the end of the survey process, has helped all trachoma elimination stakeholders to know where interventions are needed, where interventions can be stopped, and when elimination as a public health problem has been achieved. Flexibility to meet specific country contexts, adaptation to changes in global guidance and adjustments in response to user feedback have facilitated innovation in evidence-based methodologies, and supported health ministries to strive for global disease control targets.</p