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

Purpose: 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.

Methods: 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.

High prevalence of trachomatous inflammation-follicular with no trachomatous trichiasis: can alternative indicators explain the epidemiology of trachoma in Côte d'Ivoire?

Baseline trachoma surveys in Côte d'Ivoire (2019) identified seven evaluation units (EUs) with a trachomatous inflammation-follicular (TF) prevalence ≥10%, but a trachomatous trichiasis (TT) prevalence in individuals ≥15 y of age below the elimination threshold (0.2%). Two of these EUs, Bondoukou 1 and Bangolo 2, were selected for a follow-up survey to understand the epidemiology of trachoma using additional indicators of Chlamydia trachomatis infection (DNA from conjunctival swabs) and exposure (anti-Pgp3 and Ct694 antibodies from dried blood spots [DBSs]).

Explaining the continuing high prevalence of trachomatous trichiasis unknown to the health system in evaluation units: a mixed methods explanatory study in four trachoma-endemic countries.

Background: We explored reasons for continuing higher-than-anticipated prevalence of trachomatous trichiasis (TT) unknown to the health system in population-based prevalence surveys in evaluation units where full geographical coverage of TT case finding was reported.

Methods: A mixed-methods study in Ethiopia, Kenya, Nigeria and Tanzania was conducted. We compared data from clinical examination, campaign documentation and interviews with original trachoma impact survey (TIS) results.

Understanding the Role of Gender in Trichiasis Case Finding in Tanzania.

Purpose: Despite the importance of trachomatous trichiasis (TT) case-finding activities in national trachoma elimination campaigns, the scientific literature on the determinants of good outcomes - finding and managing all TT cases - is still sparse. In Tanzania, we studied differences in case finding activities and outcomes between male and female case finders.

Methods: This case study was conducted in two districts in Tanzania in 2021-2022.

The Prevalence of Trachomatous Trichiasis in People Aged 15 Years and Over in Six Evaluation Units of Gaoual, Labé, Dalaba and Beyla Districts, Guinea.

Purpose: Trachoma is a public health problem in 42 countries. Inflammation associated with repeated ocular infection with can cause the eyelid to scar and turn inwards, resulting in the eyelashes rubbing against the eyeball, known as trachomatous trichiasis (TT). In Guinea, baseline surveys conducted in 2013 reported inflammatory trachoma prevalences below the World Health Organization (WHO) threshold for elimination, but TT prevalences above threshold.

Developing comic strips promoting diabetic retinopathy screening in Kilimanjaro, Tanzania, using Intervention Mapping.

Introduction: Intervention Mapping is the protocol used by the Kilimanjaro Diabetic Programme to plan, develop, implement, and evaluate an evidence-based screening programme for diabetic retinopathy. Two comic strips were developed to deliver the message on the need for diabetic retinopathy screening.

Objectives: The first objective was to develop a culturally appropriate and accessible health message to promote diabetic retinopathy screening for the target audience.

Characteristics and perspectives of patients with postoperative trichiasis in Hadiya Zone, Ethiopia.

Background: Postoperative trachomatous trichiasis (PTT) is a challenge for trichiasis surgery programs. Little is known about PTT patients' perceptions regarding outcomes and future disease management. This study aimed to understand the characteristics of PTT patients, how they managed trichiasis and their perceptions of prior surgeries and future surgery uptake.

Productivity, efficiency and gender equity of community mobilisation approaches in trichiasis campaigns: analysis of programmatic data from seven sub-Saharan African countries.

Background: Achieving elimination of trachoma as a public health problem in trichiasis-endemic districts requires a systematic approach to trichiasis case finding and outreach.

Methods: Programme monitoring data from seven countries for 2017-2019 were used to explore the efficiency of different community mobilisation approaches and uptake of trichiasis surgical services.

Results: Three countries (Ethiopia, Kenya and Mozambique) using broad-based community mobilisation strategies had large numbers of people presenting at outreach but only 2.

The Gambia has eliminated trachoma as a public health problem: Challenges and successes.

Trachoma is the leading infectious cause of blindness in the world and has been known to be a major public health problem in The Gambia for over 60 years. Nationwide blindness surveys, including trachoma, in 1986 and 1996 provided the foundation for a comprehensive plan to implement a trachoma elimination strategy. Impact and pre-validation surveillance surveys in 2011-13 demonstrated that active trachoma was below WHO threshold for elimination but trichiasis remained a public health problem.

Evaluating Precision of a Trachomatous Trichiasis (TT) Super Survey with Modulating Sample Sizes in Tanzania.

As trachoma programs move towards eliminating trachoma as a public health problem, the number of surveys necessary to evaluate the status of trachomatous trichiasis (TT) increases. Currently, the World Health Organization endorses a district-level population-based prevalence survey for trachoma that involves a two-stage cluster design. We explored the validity of implementing this survey design in larger geographic areas to gain cost efficiencies.

National approaches to trichiasis surgical follow-up, outcome assessment and surgeon audit in trachoma-endemic countries in Africa.

Background: Poor outcomes of trichiasis surgery, including postoperative trichiasis, are common in many trachoma-endemic countries in Africa. To improve outcomes, WHO recommends regular follow-up and outcome assessment of surgical cases plus audit of trichiasis surgeons.

Aims: To assess national approaches to trichiasis surgical follow-up, outcome assessment and audit, and identify national targets for good surgical outcome (defined as the percentage of patients undergoing surgery for trichiasis remaining free of post-operative trichiasis for a defined interval after surgery).

Prevalence of trachoma in the Republic of Chad: results of 41 population-based surveys.

Purpose: To estimate the prevalence of trachoma in suspected-endemic areas of Chad, and thereby determine whether trachoma is a public health problem requiring intervention.

Methods: We divided the suspected-endemic population living in secure districts into 46 evaluation units (EUs), and used the standardized methodologies of the Global Trachoma Mapping Project. A two-stage cluster-sampling procedure was adopted.

Prevalence of Trachoma in 47 Administrative Districts of Zambia: Results of 32 Population-Based Prevalence Surveys.

Purpose: A number of previous administrative-district-level baseline trachoma prevalence estimates in Zambia required verification. We used methodologies and systems for trachoma surveys considered to represent international best practice in order to generate reliable estimates of the prevalence of trachoma.

Methods: Between March 2016 and July 2017, we undertook 32 population-based prevalence surveys covering 47 administrative districts.

Progress Towards Elimination of Trachoma as a Public Health Problem in Eritrea: Results of a Systematic Review and Nine Population-based Prevalence Surveys Conducted in 2014.

Purpose: To assess Eritrea's progress towards elimination of trachoma as a public health problem, we reviewed and compiled current knowledge on the distribution and burden of trachoma in Eritrea, then undertook further population-based surveys where indicated, with support from the Global Trachoma Mapping Project (GTMP).

Methods: For the systematic review, undertaken in March 2014, we searched (1) PubMed, using the terms ((blind* or trachoma or trichiasis) AND Eritrea); (2) the online database of rapid assessments of avoidable blindness; (3) our own grey literature collections; and (4) the Global Atlas of Trachoma database. In June and July 2014, we conducted nine population-based prevalence surveys, for each of which 30 villages were systematically selected with probability proportional to population size; in each village, 30 households were systematically selected.

Use of an inexpensive magnifier with light source in the diagnosis of trichiasis among community-based case finders in Nigeria.

Purpose: Trichiasis case finding is challenging in many trachoma endemic countries. We sought to determine how the use of an inexpensive hand-held magnifier with light source aids in the diagnosis of people with trichiasis.

Methods: We undertook a study on the use of the "Wilson", an inexpensive hand-held magnifier with light source between two groups of trained case finders: community drug distributors (CDD) volunteers and non-health volunteers.

Prevalence of trachoma in four marakez of Elmenia and Bani Suef Governorates, Egypt.

Purpose: In 2015, to determine where interventions are needed to eliminate trachoma as a public health problem from Egypt, we initiated population-based prevalence surveys using the Global Trachoma Mapping Project platform in four suspected-endemic marakez (districts; singular: markaz) of the governorates of Elmenia and Bani Suef.

Methods: In each markaz, 30 households were selected in each of 25 villages. Certified graders examined a total of 3682 children aged 1-9 years in 2993 households, noting the presence or absence of trachomatous inflammation-follicular (TF) and trachomatous inflammation-intense (TI) in each eye.

Prevalence of trachoma in Yemen: results of population-based prevalence surveys of 42 evaluation units in nine governorates.

Purpose: In suspected trachoma-endemic areas of Yemen, we sought to determine the prevalence of the sign trachomatous inflammation-follicular (TF) in children aged 1-9 years, and the potential individual and household risk factors for TF in that age group. We also sought to determine the prevalence of trichiasis in adults aged ≥15 years.

Methods: We conducted a cluster-sampled survey in each of 42 evaluation units (EUs) comprising 166 rural districts of nine Governorates (Adh Dhale'a, Al Hodeihah, Al Jawf, Hadramoot, Hajjah, Ibb, Lahj, Ma'rib, Taiz) using the Global Trachoma Mapping Project systems and methodologies.

Trachoma in Viet Nam: results of 11 surveillance surveys conducted with the Global Trachoma Mapping Project.

Purpose: Following interventions against trachoma in Viet Nam, impact surveys conducted in 2003-2011 suggested that trachoma was no longer a public health problem. In 2014, we undertook surveillance surveys to estimate prevalence of trachomatous inflammation-follicular (TF) and trichiasis.

Methods: A population-based prevalence survey was undertaken in 11 evaluation units (EUs) encompassing 24 districts, using Global Trachoma Mapping Project methods.