Using model-based geostatistics for assessing the elimination of trachoma.

BACKGROUND: Trachoma is the commonest infectious cause of blindness worldwide. Efforts are being made to eliminate trachoma as a public health problem globally. However, as prevalence decreases, it becomes more challenging to precisely predict prevalence. We demonstrate how model-based geostatistics (MBG) can be used as a reliable, efficient, and widely applicable tool to assess the elimination status of trachoma. METHODS: We analysed trachoma surveillance data from Brazil, Malawi, and Niger. We developed geostatistical Binomial models to predict trachomatous inflammation-follicular (TF) and trachomatous trichiasis (TT) prevalence. We proposed a general framework to incorporate age and gender in the geostatistical models, whilst accounting for residual spatial and non-spatial variation in prevalence through the use of random effects. We also used predictive probabilities generated by the geostatistical models to quantify the likelihood of having achieved the elimination target in each evaluation unit (EU). RESULTS: TF and TT prevalence varied considerably by country, with Brazil showing the lowest prevalence and Niger the highest. Brazil and Malawi are highly likely to have met the elimination criteria for TF in each EU, but, for some EUs, there was high uncertainty in relation to the elimination of TT according to the model alone. In Niger, the predicted prevalence varied significantly across EUs, with the probability of having achieved the elimination target ranging from values close to 0% to 100%, for both TF and TT. CONCLUSIONS: We demonstrated the wide applicability of MBG for trachoma programmes, using data from different epidemiological settings. Unlike the standard trachoma prevalence survey approach, MBG provides a more statistically rigorous way of quantifying uncertainty around the achievement of elimination prevalence targets, through the use of spatial correlation. In addition to the analysis of existing survey data, MBG also provides an approach to identify areas in which more sampling effort is needed to improve EU classification. We advocate MBG as the new standard method for analysing trachoma survey outputs.

Prevalence of Trachoma after Implementation of Trachoma Elimination Interventions in Oromia Regional State, Ethiopia: Results of Impact Surveys in 131 Evaluation Units Covering 139 Districts.

PURPOSE: To determine the prevalence of trachomatous inflammation-follicular (TF), trachomatous trichiasis (TT), water, sanitation, and hygiene (WASH) access in 131 evaluation units (EUs) after implementation of trachoma elimination interventions in Oromia Region, Ethiopia. METHODOLOGY: A population-based cross-sectional survey was conducted in each EU using the World Health Organization-recommended two-stage cluster-sampling methodology. Twenty-six clusters, each with a mean of 30 households were enumerated in each EU. All residents aged ≥1 year in selected households were examined for TF and TT. Information on WASH access in surveyed households was also collected through questioning the household head and direct observation. RESULTS: A total of 419,858 individuals were enumerated in 131 EUs, of whom 396,134 (94%) were examined, 54% being female. Age-adjusted EU-level prevalence of TF in children aged 1-9 years ranged from 0.15% (95% confidence interval [CI]: 0.0-0.4) to 37.5% (95% CI: 31.1-43.7). The TF prevalence was <5% in 73/131 (56%) EUs. The EU-level age- and gender-adjusted prevalence of TT unknown to the health system among people aged ≥15 years ranged from 0.001% (95% CI: 0.00-0.02) to 2.2% (95% CI: 1.1-3.1) with 37/131 (28%) EUs having a prevalence <0.2%. Only 48% of all households surveyed had access to improved water sources for drinking. Approximately 96% of households did not have an improved latrine. CONCLUSION: Oromia is on the path towards elimination of trachoma as a public health problem.

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. Trichiasis-only surveys in 2019 demonstrated that trichiasis was below WHO thresholds for elimination and in 2020 the Government of The Gambia completed and submitted its dossier for validation of elimination as a public health problem. Challenges that The Gambia faced on the pathway to elimination included effective use of data for decision making, poor trichiasis surgical outcomes, lack of access to antibiotic treatment for low prevalence districts, high attrition of ophthalmic nurses trained as trichiasis surgeons, unexpected active trachoma in madrassas, the misalignment of elimination of active trachoma and trichiasis, trichiasis in urban settings, and maintaining the quality of surgery post-elimination when trichiasis cases are rare. Elimination of trachoma does not end with the submission of an elimination dossier; The Gambia will need to sustain monitoring and support over the coming years.

The costs of monitoring trachoma elimination: Impact, surveillance, and trachomatous trichiasis (TT)-only surveys.

BACKGROUND: Although trachoma causes more cases of preventable blindness than any other infectious disease, a combination of strategies is reducing its global prevalence. As a district moves toward eliminating trachoma as a public health problem, national programs conduct trachoma impact surveys (TIS) to assess whether to stop preventative interventions and trachoma surveillance surveys (TSS) to determine whether the prevalence of active trachoma has rebounded after interventions have halted. In some contexts, programs also conduct trachomatous trichiasis (TT)-only surveys. A few costing studies of trachoma prevalence surveys exist, but none examine TIS, TSS, or TT-only surveys. METHODOLOGY/PRINCIPAL FINDINGS: We assessed the incremental financial cost to the national program of TIS, TSS, and TT-only surveys, which are standardized cluster-sampled prevalence surveys. We conducted a retrospective review of expenditures and grant disbursements for TIS and TSS in 322 evaluation units in 11 countries between 2011 and 2018. We also assessed the costs of three pilot and five standard TT-only surveys in four countries between 2017 and 2018. The median cost of TIS and TSS was $8,298 per evaluation unit [interquartile range (IQR): $6,532-$10,111, 2017 USD]. Based on a linear regression with bootstrapped confidence intervals, after controlling for country, costs per survey did not change significantly over time but did decline by $83 per survey implemented in a single round (95% CI: -$108 --$63). Of total costs, 80% went to survey fieldwork; of that, 58% went towards per diems and 38% towards travel. TT-only surveys cost a median of $9,707 (IQR: $8,537-$11,635); within a given country, they cost slightly more (106% [IQR: 94%-136%]) than TIS and TSS. CONCLUSIONS/SIGNIFICANCE: The World Health Organization requires trachoma prevalence estimates for validating the elimination of trachoma as a public health problem. This study will help programs improve their planning as they assemble resources for that effort.

Operational adaptations of the trachoma pre-validation surveillance strategy employed in Ghana: a qualitative assessment of successes and challenges.

BACKGROUND: In 2009 Ghana began to design a trachoma pre-validation surveillance plan, based on then-current WHO recommendations. The plan aimed to identify active trachoma resurgence and identify and manage trichiasis cases, through both active and passive surveillance approaches. This paper outlines and reviews the adaptations made by Ghana between 2011 and 2016. The assessment will provide a learning opportunity for a number of countries as they progress towards elimination status. METHODS: A mixed methods approach was taken, comprising in-depth interviews and documents review. Between January and April 2016, 20 in-depth interviews were conducted with persons involved in the operationalisation of the trachoma surveillance system from across all levels of the health system. A three-tier thematic coding framework was developed using a primarily inductive approach but also allowed for a more iterative approach, which drew on aspects of grounded theory. RESULTS: During the operationalisation of the Ghana surveillance plan there were a number of adaptations (as compared to the WHO recommendations), these included: (i) Inclusion of surveillance of active trachoma in the passive surveillance approach, as compared to trichiasis alone. Issues with case identification, challenges in implementation coverage and a non-specific reporting structure hampered effectiveness; (ii) Random selection and increase in number of sites selected for the active surveillance component. This likely lacked the spatiotemporal power to be able to identify recrudescence in a timely manner; (iii) Targeted trichiasis door-to-door case searches, led by ophthalmic nurses. An effective methodology to identify trichiasis cases but resource intensive; (iv) A buddy system between ophthalmic nurses to support technical skills in an elimination setting where it is difficult to attain diagnostic and surgical skills, due to a lack of cases. The strategy did not take into account the loss of proficiency within experienced personnel. CONCLUSIONS: Ghana developed a comprehensive surveillance system that exceeded the WHO recommendations but issues with sensitivity and specificity likely led to an inefficient use of resources. Improved targeted surveillance strategies for identification of recrudescence and trichiasis case searches, need to be evaluated. Strategies must address the contextual changes that arise because of transmission decline, such as loss of surgical skills.

Achieving the endgame: Integrated NTD case searches.

Trachoma and Guinea Worm Disease (GWD) are neglected tropical diseases (NTD) slated for elimination as a public health problem and eradication respectively by the World Health Organization. As these programs wind down, uncovering the last cases becomes an urgent priority. In 2010, Ghana Health Services, along with The Carter Center, Sightsavers, and other partners, conducted integrated case searches for both GWD and the last stage of trachoma disease, trachomatous trichiasis (TT), as well as providing surgical treatment for TT to meet elimination (and eradication targets). House to house case searches for both diseases were conducted and two case management strategies were explored: a centralized referral to services method and a Point of Care (POC) delivery method. 835 suspected TT cases were discovered in the centralized method, of which 554 accepted surgery. 482 suspected TT cases were discovered in the POC method and all TT cases accepted surgery. The cost per TT case examined was lower in the POC searches compared to the centralized searches ($19.97 in the POC searches and $20.85 in the centralized searches). Both strategies resulted in high surgical uptake for TT surgery, with average uptakes of 72.4% and 83.9% for the centralized and POC searches respectively. We present here that house to house case searches offering services at POC are feasible and a potential tool for elimination and eradication programs nearing their end.

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. All consenting residents of selected households aged ≥1 year were examined by GTMP-certified graders for signs of trachoma. Data on household-level access to water and sanitation were also collected. RESULTS: One previous rapid assessment of avoidable blindness, three peer-reviewed publications, and two grey literature reports detailing sets of trachoma prevalence surveys conducted in 2006 and 2011, respectively, were located. Post-intervention impact surveys were needed in seven evaluation units (EUs, framed at sub-Zoba-level: population range 40,000-120,000) of Debub and Northern Red Sea, while baseline surveys were needed in two EUs of Anseba. Four of the seven impact survey EUs and both baseline survey EUs returned trachomatous inflammation-follicular prevalences in 1-9-year-olds of ≥5%; six of the seven impact survey EUs and one of the two baseline survey EUs returned trichiasis prevalences in ≥15-year-olds of ≥0.2%. The prevalence of access to water and sanitation varied widely between EUs. CONCLUSION: Interventions are still required in Eritrea to eliminate trachoma as a public health problem. Data from these surveys will guide the Ministry of Health to undertake programme planning using a sound evidence base.

Elimination of trachoma as a public health problem in Ghana: Providing evidence through a pre-validation survey.

BACKGROUND: In order to achieve elimination of trachoma, a country needs to demonstrate that the elimination prevalence thresholds have been achieved and then sustained for at least a two-year period. Ghana achieved the thresholds in 2008, and since 2011 has been implementing its trachoma surveillance strategy, which includes community and school screening for signs of follicular trachoma and trichiasis, in trachoma-endemic districts. In 2015-2016, the country conducted a district level population-based survey to validate elimination of trachoma as a public health problem. METHODS: As per WHO recommendations, a cross-sectional survey, employing a two-stage cluster random sampling methodology, was used across 18 previously trachoma endemic districts (evaluation units (EUs) in the Upper West and Northern Regions of Ghana. In each EU 24 villages were selected based on probability proportional to estimated size. A minimum of 40 households were targeted per village and all eligible residents were examined for clinical signs of trachoma, using the WHO simplified grading system. The number of trichiasis cases unknown to the health system was determined. Household environmental risk factors for trachoma were also assessed. RESULTS: Data from 45,660 individuals were examined from 11,099 households across 18 EUs, with 27,398 (60.0%) children aged 1-9 years and 16,610 (36.4%) individuals 15 years and above All EUs had shown to have maintained the WHO elimination threshold for Trachomatous inflammation-Follicular (TF) (<5.0% prevalence) in children aged 1-9 years old. The EU TF prevalence in children aged 1-9 years old ranged from between 0.09% to 1.20%. Only one EU (Yendi 0.36%; 95% CI: 0.0-1.01) failed to meet the WHO TT elimination threshold (< 0.2% prevalence in adults aged 15 and above). The EU prevalence of trichiasis (TT) unknown to the health system in adults aged ≥15 years, ranged from 0.00% to 0.36%. In this EU, the estimated TT backlog is 417 All TT patients identified in the study, as well as through on-going surveillance efforts will require further management. A total of 75.9% (95% CI 72.1-79.3, EU range 29.1-92.6) of households defecated in the open but many households had access to an improved water source 75.9% (95%CI: 71.5-79.8, EU range 47.4-90.1%), with 45.5% (95% CI 41.5-49.7%, EU range 28.4-61.8%) making a round trip of water collection < 30 minutes. CONCLUSION: The findings from this survey indicate elimination thresholds have been maintained in Ghana in 17 of the 18 surveyed EUs. Only one EU, Yendi, did not achieve the TT elimination threshold. A scheduled house-by-house TT case search in this EU coupled with surgery to clear the backlog of cases is necessary in order for Ghana to request validation of elimination of trachoma as a public health problem.

Estimating the Future Impact of a Multi-Pronged Intervention Strategy on Ocular Disease Sequelae Caused by Trachoma: A Modeling Study.

PURPOSE: Trachoma control programs are underway in endemic regions worldwide. They are based on the SAFE strategy (Surgery for trichiasis, Antibiotic distribution, Facial cleanliness, and Environmental improvement). Although much is known about the effect of community-wide treatment with antibiotics on the prevalence of Chlamydia trachomatis, the impact of the SAFE strategy on severe ocular disease sequelae (the main focus of the Global Elimination of blinding Trachoma by 2020 program) remains largely unknown. METHODS: We use a mathematical model to explore the impact of each of the components of the SAFE strategy, individually and together, on disease sequelae, arising from repeat infection and subsequent conjunctival scarring. We ask whether two elimination goals, to reduce the prevalence of trachomatous trichiasis to 1 per 1000 persons, and the incidence of corneal opacity to 1 per 10,000 persons per annum, are achievable, and which combinations of interventions have the greatest impact on these indicators. RESULTS: In high prevalence communities (here, >20% infection of children aged 1-9 years), a combination of efforts is needed to bring down sustainably the prevalence and incidence of ocular disease sequelae. CONCLUSION: The mass delivery of antibiotics is highly beneficial for the clearance of infection, inflammation and prevention of subsequent scarring, but needs to be supplemented with sustained reductions in transmission and surgery to consider realistically the elimination of blindness by the year 2020.

Comparison of trichiasis recurrence after primary bilamellar tarsal rotation or anterior lamellar repositioning surgery performed for trachoma.

BACKGROUND: To compare the trichiasis recurrence rate following bilamellar tarsal rotation or anterior lamellar repositioning, performed as primary surgery for trachomatous trichiasis. DESIGN: Retrospective consecutive case series. PARTICIPANTS: All cases of trachomatous trichiasis undergoing primary surgical correction at Alice Springs Hospital, Alice Springs, Northern Territory, Australia, between 1 June 2001 and 11 June 2011 were included. METHODS: Retrospective chart review. Key baseline, operative and outcome details were collected from the notes. MAIN OUTCOME MEASURE: Recurrent trichiasis was defined as one or more lashes touching the cornea, resulting in recurrent symptoms of trichiasis and warranting further surgery in the opinion of the treating ophthalmologist. RESULTS: Sixty-seven BTR and eighteen ALR procedures were performed, with BTR being performed from 2001 to 2008, and ALR from 2008 to 2011. The mean follow-up times were significantly different for the BTR group (1654 days) and for the ALR group (673 days)(P < 0.001). Kaplan-Meier survival analysis did not reveal any significant differences in recurrence rate between the two procedures overall (P = 0.935). Analysis of the 2008 calendar year (the only year where both procedures were performed and therefore had equal follow-up times) suggested that ALR might have a lower recurrence rate (1/10 ALR recurrences vs. 4/6 BTR recurrences, P = 0.181). CONCLUSIONS: The results do not demonstrate a difference in the recurrence rate between the two techniques. Inconsistent follow times however leave uncertainty in this result, and a larger prospective randomised study is warranted to address this question.

Australian trachoma surveillance annual report, 2011.

Australia remains the only developed country to have endemic trachoma in some regions. Endemic levels of trachoma in Australia are found predominantly in remote and very remote Aboriginal communities. Data are collected from Aboriginal communities designated at risk for endemic trachoma (defined as a prevalence of 5% or greater among children) in the Northern Territory, South Australia and Western Australia. This report presents data collected in 2011. The World Health Organization (WHO) grading criteria were used to diagnose cases of trachoma in Aboriginal children with jurisdictions focusing screening activities on the 5-9 year age group. The prevalence of trachoma within a community was used to guide appropriate treatment strategies as a public health response. Aboriginal adults aged 40 years or older were screened for trichiasis. Population screening coverage for trichiasis in 2011 was 9% with a prevalence of 2% in those adults screened. Trachoma screening coverage of the estimated populationof children aged 5-9 years in at-risk communities was 65%. Trachoma prevalence among children aged 5-9 years who were screened was 7%. Of the communities screened, 47% were found to have no cases of active trachoma and 40% were found to have endemic levels. Treatment was required in 80 at-risk communities screened. Treatment coverage of active cases and their contacts varied between jurisdictions, ranging from 53% to 98%. This report provides evidence of increasing coverage of trachoma screening and control activities. In the Northern Territory and Western Australia, there is also evidence of a decline in the prevalence of infection that may be attributable to an improvement in control activities. Despite these apparent advances, trachoma prevalence remains at endemic levels in many communities in remote Australia. Continued efforts are required to ensure that Australia remains on track to reach the goal of elimination by 2020 or sooner.

Three-year outcomes of the surgery for trichiasis, antibiotics to prevent recurrence trial.

OBJECTIVE: To determine whether treatment with oral azithromycin compared with topical tetracycline reduces the recurrence of trichiasis for up to 3 years following surgery for trichiasis. METHODS: The Surgery for Trichiasis, Antibiotics to Prevent Recurrence (STAR) trial is a randomized, single-masked, clinical trial conducted in southern Ethiopia, a region where trachoma is hyperendemic. A total of 1452 patients who underwent trichiasis surgery were randomly assigned at a 2:1 ratio to either a single dose of oral azithromycin (1 g) or topical tetracycline (twice per day for 6 weeks) following surgery. MAIN OUTCOME MEASURES: Recurrence of trichiasis within 3 years following surgery. RESULTS: The rate of recurrence was 10% in the azithromycin group and 13% in the tetracycline group. The azithromycin group had a 22% reduction in recurrence of trichiasis 3 years after surgery compared with the tetracycline group (P = .13). Severity of entropion at baseline was the most significant predictor of recurrence of trichiasis at 3 years. CONCLUSION: Trichiasis recurrence rates in the STAR trial remained low for up to 3 years following surgery. The protective effect of a single dose of azithromycin was less than at 1 year and, although not statistically significant, was still suggestive up to 3 years following trichiasis surgery. APPLICATION TO CLINICAL PRACTICE: A single dose of azithromycin after surgery remains an integral component of the World Health Organization's strategy for the elimination of trachoma by the year 2020.