Using Model-Based Geostatistics to Refine Population-Based Estimates of Trachoma Prevalence: Update from a Technical Consultation.

To explore how model-based geostatistics (MBG) could support trachoma elimination efforts, a technical consultation was held on March 4 and 5, 2024 by the Centre for Health Informatics, Computing, and Statistics at Lancaster University, United Kingdom, a WHO Collaborating Centre on Geostatistical Methods for Neglected Tropical Disease Research. The meeting aimed to foster collaboration for sharing insights on using MBG for decision-making; showcase its applications in assessing trachoma elimination status; address challenges, such as setting the probability threshold for elimination and resolving conflicts between survey and MBG evidence; and discuss considerations for integrating MBG into Tropical Data. Participants, including trachoma program managers, experts, academics, donors, and statisticians, reviewed MBG applications, discussed ongoing studies, identified knowledge gaps, and planned future work.

Characterizing trachoma elimination using serology.

Trachoma is targeted for global elimination as a public health problem by 2030. Measurement of IgG antibodies in children is being considered for surveillance and programmatic decision-making. There are currently no programmatic guidelines based on serology, which represents a generalizable problem in seroepidemiology and disease elimination.

Prevalence of ocular Chlamydia trachomatis infection and antibodies within districts persistently endemic for trachoma, Amhara, Ethiopia.

Background: Persistent trachoma is increasingly recognized as a serious concern for the global trachoma program. Persistent trachoma is defined as those districts that have had two or more trachoma impact surveys in which the trachomatous inflammation-follicular (TF) prevalence has never been <5%, the elimination threshold for TF. Enhanced tools such as infection and serological monitoring elucidate long-term transmission patterns within persistent districts.

Prevalence of Ocular Chlamydia trachomatis and Active Trachoma among Children in Merhabete District, Amhara, Ethiopia.

There have been significant reductions in the burden of trachoma worldwide. However, some districts have experienced persistently high trachoma prevalence despite many years of intervention. Here, we report the epidemiology of trachoma in Merhabete, Ethiopia, a district in the Amhara Region that has been receiving azithromycin mass drug administration (MDA) since 2009.

Progress towards the elimination of trachoma as a public health problem in four counties of Eastern Equatoria State, Republic of South Sudan.

Background: Trachoma is targeted by the World Health Organization (WHO) for elimination as a public health problem by 2030. Trachoma impact surveys using standardised methodology are recommended to monitor progress towards elimination and to determine eligibility for continued surgery, antibiotics, facial cleanliness, and environmental improvement (SAFE) interventions. From 2007 to 2015, four counties of Eastern Equatoria State, South Sudan, received three to five rounds of mass drug administration with antibiotics.

Correlates of Trachoma Recrudescence: Results from 51 District-Level Trachoma Surveillance Surveys in Amhara, Ethiopia.

Trachoma recrudescence is a serious concern for trachoma control programs. Programs define recrudescence as the return of trachomatous inflammation-follicular (TF) prevalence above elimination threshold (≥5%) on district-level trachoma surveillance surveys (TSSs). This study aimed to determine potential correlates of trachoma recrudescence within a historically highly endemic region.

Correlation of Clinical Severity of Trachomatous Inflammation and Chlamydia trachomatis Bacterial Load.

The purpose of this study was to investigate the correlation between bacterial load of Chlamydia trachomatis as measured from quantitative polymerase chain reaction (qPCR) and the relative clinical severity of trachomatous inflammation. Individuals with trachoma from rural communities in Ethiopia had photographs taken as well as swabs obtained of the upper tarsal conjunctivas. Conjunctival swabs were processed with PCR assay, which provided quantitative results of ocular chlamydial load.

Computer Vision Identification of Trachomatous Inflammation-Follicular Using Deep Learning.

Purpose: Trachoma surveys are used to estimate the prevalence of trachomatous inflammation-follicular (TF) to guide mass antibiotic distribution. These surveys currently rely on human graders, introducing a significant resource burden and potential for human error. This study describes the development and evaluation of machine learning models intended to reduce cost and improve reliability of these surveys.

Compliance with tetracycline eye ointment during annual mass drug administration for trachoma control in the Amhara region, Ethiopia.

Objectives: A 6-week course of tetracycline eye ointment is an alternative to single -dose oral azithromycin in annual mass drug administration for trachoma control. Compliance with the recommended tetracycline eye ointment regimen has not been well characterised when administered as part of a trachoma control program.

Methods: A routine mass drug administration for trachoma was carried out in 40 communities in the Amhara region of Ethiopia.

The cost of mass drug administration for trachoma in two counties of the Republic of South Sudan.

Community-wide distribution of azithromycin, otherwise known as mass drug administration (MDA), is a component of the World Health Organization-endorsed SAFE strategy for the elimination of trachoma as a public health problem. In the Republic of South Sudan, 2.9 million people are known to live in areas that are known to require interventions and warrant MDA.

Photographic grading to evaluate facial cleanliness and trachoma among children in Amhara region, Ethiopia.

Background: Promotion of facial cleanliness is recommended for the elimination of blinding trachoma, largely because of observational studies that have found an association between various measures of facial uncleanliness and trachoma. However, when a field grader assesses both facial cleanliness and trachoma, associations may be biased. Assessment of photographs of the face and conjunctiva by masked graders may provide a less biased estimate of the relationship between facial cleanliness and trachoma.

Impact of a School Trachoma Program Emphasizing Facial Cleanliness and Environmental Improvement in Amhara, Ethiopia.

The SAFE (Surgery, Antibiotics, Facial cleanliness, Environmental improvement) strategy is the WHO's endorsed approach for eliminating trachoma as a public health problem; however, not all components have been treated equally. Historically, the F and E components have not been prioritized owing to their perceived complexity. With school enrollment increasing in Ethiopia, development of a national school health program that is focused on the F and E components represents an opportunity to strengthen the SAFE strategy in the country.

Unravelling Chlamydia trachomatis diversity in Amhara, Ethiopia: MLVA-ompA sequencing as a molecular typing tool for trachoma.

Trachoma is the leading infectious cause of blindness worldwide and is now largely confined to around 40 low- and middle-income countries. It is caused by Chlamydia trachomatis (Ct), a contagious intracellular bacterium. The World Health Organization recommends mass drug administration (MDA) with azithromycin for treatment and control of ocular Ct infections, alongside improving facial cleanliness and environmental conditions to reduce transmission.

Wait and watch: A trachoma surveillance strategy from Amhara region, Ethiopia.

Background: Trachoma recrudescence after elimination as a public health problem has been reached is a concern for control programs globally. Programs typically conduct district-level trachoma surveillance surveys (TSS) ≥ 2 years after the elimination threshold is achieved to determine whether the prevalence of trachomatous inflammation-follicular (TF) among children ages 1 to 9 years remains <5%. Many TSS are resulting in a TF prevalence ≥5%.

Seroreversion to Chlamydia trachomatis Pgp3 Antigen Among Children in a Hyperendemic Region of Amhara, Ethiopia.

Monitoring trachoma transmission with antibody data requires characterization of decay in IgG to Chlamydia trachomatis antigens. In a 3-year longitudinal cohort in a high-transmission setting, we estimated a median IgG half-life of 3 years and a seroreversion rate of 2.5 per 100 person-years (95% confidence interval, 1.

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.

How well do coverage surveys and programmatically reported mass drug administration coverage match? Results from 214 mass drug administration campaigns in 15 countries, 2008-2017.

Introduction: Delivering preventive chemotherapy through mass drug administration (MDA) is a central approach in controlling or eliminating several neglected tropical diseases (NTDs). Treatment coverage, a primary indicator of MDA performance, can be measured through routinely reported programmatic data or population-based coverage evaluation surveys. Reported coverage is often the easiest and least expensive way to estimate coverage; however, it is prone to inaccuracies due to errors in data compilation and imprecise denominators, and in some cases measures treatments offered as opposed to treatments swallowed.

Monitoring transmission intensity of trachoma with serology.

Trachoma, caused by ocular infection, is targeted for global elimination as a public health problem by 2030. To provide evidence for use of antibodies to monitor transmission, we collated IgG responses to Pgp3 antigen, PCR positivity, and clinical observations from 19,811 children aged 1- 9 years in 14 populations. We demonstrate that age-seroprevalence curves consistently shift along a gradient of transmission intensity: rising steeply in populations with high levels of infection and active trachoma and becoming flat in populations near elimination.

Seroreversion to Pgp3 antigen among children in a hyperendemic region of Amhara, Ethiopia.

Monitoring trachoma transmission with antibody data requires characterization of decay in IgG to antigens. In a three-year longitudinal cohort in a high transmission setting, we estimated a median IgG half-life of 3 years and a seroreversion rate of 2.5 (95% CI: 1.