The Epidemiology of Trachoma in Mozambique: Results of 96 Population-Based Prevalence Surveys

Magnitude of Active Trachoma Among Host and Refugee Children in Gambella Regional State, Ethiopia

Background

Trachoma is a serious public health concern and cause of blindness globally. Despite its vulnerability to all ages, children are more vulnerable to its adverse outcomes and devastating complications. This study assessed the magnitude of trachoma among children in host and refugee communities in Gambella, Ethiopia.

Methods

A community-based comparative survey was done among 743 participants. Multistage sampling technique was used to select participants. Selected children were examined for trachoma using a 2.5x binocular loupe and graded using the World Health Organization (WHO) simplified grading system. A standardized, structured, and pretested tool was used to collect the data. Data were collected through interviews and observation. Bivariable and multivariable logistic regression analyses were done to identify the associated factors. Variable with a p-value <0.05 was considered statistically significant.

Results

The magnitude of active trachoma was 119 (16.5%; 95% CI: 13.5, 21.4) with 36 (14.5%; 95% CI: 11.9, 18.8) and 83 (17.5%; 95% CI: 14.3, 22.7) from refugees and host communities, respectively. Poor knowledge of caregiver about trachoma [AOR = 3.55, 95% CI: (1.48, 8.85)], presence of human feces near the house [AOR = 4.57, 95% CI: (1.84, 11.34)], presence of garbage near the house [AOR = 4.07, 95% CI: (1.34, 12.36)], and the presence of flies on the face of the child [AOR = 3.42, 95% CI: (1.32, 8.84)] were significantly associated factors with active trachoma.

Conclusion

Overall, one-sixth of children had experienced active trachoma. The magnitude of trachoma was higher in the host community compared to the refugees. Proper waste disposal and personal hygiene measures are important measures that should be addressed to tackle the problem.

A review of latrine front-end characteristics associated with microbial infection risk; reveals a lack of pathogen density data

Unsafe sanitation accounts for an estimated 898,000 global deaths annually. The faecal pathogen transmission pathway is complex with several possible routes. Latrine front-end characteristics and usage behaviours are one key transmission pathway for microbial pathogens, however, there has not yet been a synthesis of the available research. This review aims to compare the microbial infection risks with latrine front-end components including any quantified microbial densities within the household latrines. This review was conducted with no restriction on the geographical location of the research. Of 118 studies reviewed, only ten (8%) have quantified the microbial density inside the household latrines compared to 109 (92%) measuring the infection risks. The reported risks were most frequent for specific bacterial (n = 34), and helminths infections (n = 32) compared to diarrhoea (n = 23), combined (n = 15), protozoan (n = 4), and viral (n = 4) infections. The infections risk decreased for using latrines lying at a higher position on the sanitation ladder (for example flush latrines) compared to those lying lower (for example pit latrines). The trend was similar for using floor materials that were easier to clean and less favourable for pathogen survival inside the latrines (for example, concrete as opposed to earth). Faecal coliforms were reported highest on the surface of the squat pan (743 CFU/cm2) of pour-flush latrines and helminths on earth floors of pit latrines (1.5 eggs and larvae per gram of soil). Irrespective of latrine type and its position on the sanitation ladder, a dirty latrine, evidenced by a visible lack of cleanliness, significantly increased the risk for all infections. This study recommends that effective microbial infection risk reduction in latrines can be gained efficiently by ensuring washable surfaces and consistent cleaning practices. Future studies should include more rigorous measurements of microbial densities in various latrine types incorporating the different front-end components and usage behaviours.

Exploring multi-level risk factors and post-war burdens of trachomatous trichiasis among displaced population in Raya Kobo districts, implication for urgent action

AIM

To estimate post-war burdens of trachomatous trichiasis (TT) and multi-level risk factors among displaced population in Raya Kobo districts, implication for urgent action.

METHODS

A community-based cross-sectional study was conducted among 603 participants from randomly selected 14 displaced slums in the Raya Kobo district. The data was collected from February 16th to March 30th, 2023. Study participants were selected using the multistage sampling technique. A structured questionnaire and ophthalmic loupe with ×2.5 magnificence were used to collect from participants. Multi-level binary logistic regression was used to determine associated factors with TT infection. Adjusted odds ratio (AOR) with 95% confidence interval (CI) were claimed for the strength of association at P<0.05.

RESULTS

We recruited 602 (99.9%) participants for the final analysis. From the total, 126 (20.9%) and 98 (16.3%, 95%CI: 13.5%-19.4%) participants were diagnosed with active trachoma & TT infection, respectively. Being age ≥45y (AOR=7.9, 95%CI: 2.4-25.3), having multiple eye infections (AOR=2.73, 95%CI: 1.47-5.29), poor wealth index (AOR=9.2; 95%CI: 2.7-23.7) and twice face washing per day (AOR=0.082, 95%CI: 0.03-0.21) has identified as individual as factors for TT infection. Whereas, distance between clean water source ≥10 km (AOR=6.5, 95%CI: 3.9-31.3), and latrine availability (AOR=0.35, 95%CI: 0.21-0.58) were the two community-level factors associated with TT infections.

CONCLUSION

The high prevalence of TT infection post-war throughout the study districts indicates a need for urgent clinical intervention in addition to rapid scaling up surgery, antibiotics, facial cleanliness, and environmental improvement (SAFE) strategies, strategy for high-risk population. Age≥45y, distance from the clean water source, poor wealth indexes, and eye infection are identified to be risk factors for TT infection. Furthermore, community-level preventative factors for TT infection are found as latrine availability and face washing practice.

Prevalence of active trachoma infection and associated factors post-war resettled population in raya kobo districts, North East Ethiopia: A community-based cross-sectional study in 2022

Background

Active trachoma infection poses a serious threat to public health, particularly for those who live in an unprivileged area and has practiced open-field defecation. This study aimed to estimate the prevalence of active trachoma infection and associated factors in the post-war resettled population in Raya Kobo district, North East Ethiopia: a community-based cross-sectional study in 2022.

Methods

A community-based cross-sectional study was conducted among 602 participants randomly selected in 14 slum villages in Raya Kobo from February 16th to March 30th, 2023. After the data was collected using a semi-structured questionnaire and entered into Epi-data version 3.2. The study participants were chosen using a two-stage sampling process. Binary logistic regression was used to identify factors for active trachoma infection. Adjusted odds ratios (AORs) with 95% confidence intervals (CIs) were claimed for the strength of association at p < 0.05.

Results

Overall, 602 (99.9%) study participants were included in the final analysis. At the end of the study period, 126 (20.9) participants developed active trachoma infection. On multivariable analysis, were aged ≥45 years (AOR = 7.9, 95% CI = 2.4-25.3), history of eye infection (AOR = 3.7, 95% CI = 2.4-10.4, p = 0.001), were poor wealth index (AOR = 9.2, 95% CI = 2.7-23.7), having separated kitchen (AOR = 4.05, 95% CI = 1.86-8.86), living with animals (AOR = 5.92, 95% CI = 2.31-14.7) and having got administration of mass-drug (AOR = 8.9, 95% CI = 2.36-33.6) were significant risk factors for active trachoma infection. Whereas, face washing practice regularly (AOR = 0.23, 95% CI = 0.127-0.43), and toilet availability (AOR = 0.35, 95% CI = 0.20-0.97) were preventive factors for active trachoma infection.

Conclusion

A significant prevalence of active trachoma infection was reported in the area as compared with previous findings and urgent clinical intervention, and the WHO critical SAFE strategies (surgery, antibiotics, facial cleanliness, and environmental improvement) implementation is highly needed in the area. In addition, healthcare providers should focus on information dissemination on proper latrine utilization, and washing the face regularly to prevent active trachoma infection is highly recommended.

Evaluation of facial cleanliness and environmental improvement activities: Lessons learned from Malawi, Tanzania, and Uganda

The World Health Organization promotes the SAFE (Surgery, Antibiotics, Facial cleanliness, and Environmental improvements) strategy for trachoma control and prevention. The F&E components of the strategy focus on promotion of healthy hygiene and sanitation behaviors. In order to monitor F&E activities implemented across villages and schools in Malawi, Tanzania, and Uganda, an F&E Monitoring and Evaluation (FEME) framework was developed to track quarterly program outputs and to provide the basis for a pre and post evaluation of the activities. Results showed an increase in knowledge at the school and household levels, and in some cases, an increase in presence of hand/face washing stations. However, this did not always result in a change in trachoma prevention behaviors such as facial cleanliness or keeping compounds free of human feces. The results highlight that the F&E programs were effective in increasing awareness of trachoma prevention but not able to translate that knowledge into changes in behavior during the time between pre and post-surveys. This study also indicates the potential to improve the data collection and survey design and notes that the period of intervention was not long enough to measure significant changes.

Trachoma control programs promote facial cleanliness, use of latrines, and emphasizes the importance of access to water as means to reduce trachoma transmission. To address these areas, various country ministries and supporting non-governmental organizations (NGOs) support the implementation of tailored behavior change programs. The process and results of evaluating these types of programs in Malawi, Tanzania, and Uganda are described here. The goal of this manuscript is to provide trachoma program managers and supporting NGOs with insights, recommendations, and data collection tools that could be used to support their efforts to conduct monitoring and evaluation of their current or future trachoma prevention activities.

Changes in Eye Health and Service Coverage in Nampula, Mozambique between 2011 and 2018

Purpose: Globally, there are few examples of repeated eye health surveys to assess changes in prevalence and causes of visual impairment, and service coverage over time. Two separate, unlinked rapid assessments of avoidable blindness (RAAB) were conducted in Nampula province, Mozambique in 2011 and 2018. This paper reports the observed changes and examines how the trends differ for males and females.Methods: Standard RAAB methodology was used in both studies. Two-stage cluster sampling was used to generate random samples of adults aged over 50 years. Participants underwent a simplified visual acuity (VA) exam, a lens exam and posterior segment exam using a direct ophthalmoscope for all subjects with presenting VA<6/18. Data were analysed using Stata and logistic regression models were developed to assess changes.Results: The 2011 study enrolled 3,050 people and examined 96.9% (2,954 people). The 2018 survey enrolled 4,191 people and examined 95.8% (4,015 people). Age- and sex-adjusted estimates of blindness decreased from 6.2% in 2011 to 4.5% in 2018 (z = -2.21, p = .028). Cataract surgical coverage was higher among males in both surveys (13.4% among males vs 7.7% among females in 2011, and 40.0% among males vs 19.4% among females in 2018) and the gender disparity grew between surveys.Conclusion: Significant changes were observed in the eye health and service coverage between 2011 and 2018. Further improvements to services are required to improve access for women and people with moderate visual impairment.

The Importance of Failure: How Doing Impact Surveys That Fail Saves Trachoma Programs Money

Trachoma programs use annual antibiotic mass drug administration (MDA) in evaluation units (EUs) that generally encompass 100,000–250,000 people. After one, three, or five MDA rounds, programs undertake impact surveys. Where impact survey prevalence of trachomatous inflammation—follicular (TF) in 1- to 9-year-olds is ≥ 5%, ≥ 1 additional MDA rounds are recommended before resurvey. Impact survey costs, and the proportion of impact surveys returning TF prevalence ≥ 5% (the failure rate or, less pejoratively, the MDA continuation rate), therefore influence the cost of eliminating trachoma. We modeled, for illustrative EU sizes, the financial cost of undertaking MDA with and without conducting impact surveys. As an example, we retrospectively assessed how conducting impact surveys affected costs in the United Republic of Tanzania for 2017–2018. For EUs containing 100,000 people, the median (interquartile range) cost of continuing MDA without doing impact surveys is USD 28,957 (17,581–36,197) per EU per year, whereas continuing MDA solely where indicated by impact survey results costs USD 17,564 (12,158–21,694). If the mean EU population is 100,000, then continuing MDA without impact surveys becomes advantageous in financial cost terms only when the continuation rate exceeds 71%. For the United Republic of Tanzania in 2017–2018, doing impact surveys saved enough money to provide MDA for > 1,000,000 people. Although trachoma impact surveys have a nontrivial cost, they generally save money, providing EUs have > 50,000 inhabitants, the continuation rate is not excessive, and they generate reliable data. If all EUs pass their impact surveys, then we have waited too long to do them.

Progress toward Elimination of Trachoma as a Public Health Problem in Seven Localities in the Republic of Sudan: Results from Population-Based Surveys

Trachoma is the leading cause of infectious blindness in the world. After baseline surveys demonstrated that Sudan was endemic for trachoma, the Sudan Federal Ministry of Health (FMOH) Trachoma Control Program conducted trachoma prevention and treatment interventions in endemic localities. The Sudan FMOH conducted population-based trachoma prevalence surveys between September 2016 and April 2017 in seven localities across five states of Sudan to document current trachoma prevalence estimates and measure water, sanitation, and hygiene (WASH) indicators. Children aged 1–9 years were examined for five clinical signs of trachoma, and participants of all ages were examined for trachomatous trichiasis (TT). A household questionnaire was administered to gather demographic and WASH-related information. The prevalence of trachomatous inflammation-follicular (TF) in children aged 1–9 years ranged from 0.4% (95% CI: 0.1–1.1%) to 6.4% (95% CI: 3.3–11.9%). Trachomatous trichiasis in those aged 15 years and older ranged from 0.1% (95% CI: 0.0–0.6%) to a high of 4.4% (95% CI: 2.1–9.1%). Of seven localities surveyed, four localities had achieved the elimination threshold of less than 5% TF in children aged 1–9 years. Six localities still required interventions to achieve less than 0.2% TT in those aged 15 years and older. The presence of latrine ranged from a low of 10.8% (95% CI: 5.2–21.1%) to 88.4% (CI: 81.5–93.0%) and clean face among children ranged between 69.5% (95% CI: 63.5–75.0%) and 87.5% (95% CI: 81.2–91.9%). These results demonstrate that Sudan is within reach of eliminating trachoma as a public health problem.

Estimating the Intracluster Correlation Coefficient for the Clinical Sign "Trachomatous Inflammation-Follicular" in Population-Based Trachoma Prevalence Surveys: Results From a Meta-Regression Analysis of 261 Standardized Preintervention Surveys Carried Out in Ethiopia, Mozambique, and Nigeria

Sample sizes in cluster surveys must be greater than those in surveys using simple random sampling in order to obtain similarly precise prevalence estimates, because results from subjects examined in the same cluster cannot be assumed to be independent. Therefore, a crucial aspect of cluster sampling is estimation of the intracluster correlation coefficient (ρ): the degree of relatedness of outcomes in a given cluster, defined as the proportion of total variance accounted for by between-cluster variation. In infectious disease epidemiology, this coefficient is related to transmission patterns and the natural history of infection; its value also depends on particulars of survey design. Estimation of ρ is often difficult due to the lack of comparable survey data with which to calculate summary estimates. Here we use a parametric bootstrap model to estimate ρ for the ocular clinical sign “trachomatous inflammation—follicular” (TF) among children aged 1–9 years within population-based trachoma prevalence surveys. We present results from a meta-regression analysis of data from 261 such surveys completed using standardized methods in Ethiopia, Mozambique, and Nigeria in 2012–2015. Consistent with the underlying theory, we found that ρ increased with increasing overall TF prevalence and smaller numbers of children examined per cluster. Estimates of ρ for TF were independently higher in Ethiopia than in the other countries.

Frequency and distribution of neglected tropical diseases in Mozambique: a systematic review

BACKGROUND

Neglected tropical diseases (NTDs) affect more than one billion people living in vulnerable conditions. In spite of initiatives recently contributing to fill NTDs gaps on national and local prevalence and distribution, more epidemiological data are still needed for effective control and elimination interventions.

MAIN TEXT

Mozambique is considered one of the countries with highest NTDs burden although available data is scarce. This study aims to conduct a systematic review on published available data about the burden and distribution of the different NTDs across Mozambique since January 1950 until December 2018. We identified manuscripts from electronic databases (Pubmed, EmBase and Global Health) and paper publications and grey literature from Mozambique Ministry of Health. Manuscripts fulfilling inclusion criteria were: cross-sectional studies, ecological studies, cohorts, reports, systematic reviews, and narrative reviews capturing epidemiological information of endemic NTDs in Mozambique. Case-control studies, letters to editor, case reports and case series of imported cases were excluded. A total of 466 manuscripts were initially identified and 98 were finally included after the revision following PRISMA guidelines. Eleven NTDs were reported in Mozambique during the study span. Northern provinces (Nampula, Cabo Delgado, Niassa, Tete and Zambezia) and Maputo province had the higher number of NTDs detected. Every disease had their own report profile: while schistosomiasis have been continuously reported since 1952 until nowadays, onchocerciasis and cysticercosis last available data is from 2007 and Echinococcosis have never been evaluated in the country. Thus, both space and time gaps on NTDs epidemiology have been identified.

CONCLUSIONS

This review assembles NTDs burden and distribution in Mozambique. Thus, contributes to the understanding of NTDs epidemiology in Mozambique and highlights knowledge gaps. Hence, the study provides key elements to progress towards the control and interruption of transmission of these diseases in the country.

The global burden of trichiasis in 2016

Background

Trichiasis is present when one or more eyelashes touches the eye. Uncorrected, it can cause blindness. Accurate estimates of numbers affected, and their geographical distribution, help guide resource allocation.

Methods

We obtained district-level trichiasis prevalence estimates in adults for 44 endemic and previously-endemic countries. We used (1) the most recent data for a district, if more than one estimate was available; (2) age- and sex-standardized corrections of historic estimates, where raw data were available; (3) historic estimates adjusted using a mean adjustment factor for districts where raw data were unavailable; and (4) expert assessment of available data for districts for which no prevalence estimates were available.

Findings

Internally age- and sex-standardized data represented 1,355 districts and contributed 662 thousand cases (95% confidence interval [CI] 324 thousand–1.1 million) to the global total. Age- and sex-standardized district-level prevalence estimates differed from raw estimates by a mean factor of 0.45 (range 0.03–2.28). Previously non- stratified estimates for 398 districts, adjusted by ×0.45, contributed a further 411 thousand cases (95% CI 283–557 thousand). Eight countries retained previous estimates, contributing 848 thousand cases (95% CI 225 thousand-1.7 million). New expert assessments in 14 countries contributed 862 thousand cases (95% CI 228 thousand–1.7 million). The global trichiasis burden in 2016 was 2.8 million cases (95% CI 1.1–5.2 million).

Interpretation

The 2016 estimate is lower than previous estimates, probably due to more and better data; scale-up of trichiasis management services; and reductions in incidence due to lower active trachoma prevalence.

As an individual with trichiasis blinks, the eyelashes abrade the cornea, which can lead to corneal opacity and blindness. Through high quality surgery, which involves altering the position of the eyelid margin, it is possible to reduce the number of people with trichiasis. Accurate estimates of the number of persons with trichiasis and their geographical distribution are needed in order to effectively align resources for surgery and other necessary services. We obtained district-level trichiasis prevalence estimates for 44 endemic and previously-endemic countries. We used the most recently available data and expert assessments to estimate the global burden of trichiasis. We estimated that in 2016 the global burden was 2.8 million cases (95% CI 1.1–5.2 million).

The 2016 estimate is lower than previous estimates, probably due to more and better data; scale-up of trichiasis management services; and reductions in incidence due to lower active trachoma prevalence.

Quality Assurance and Quality Control in the Global Trachoma Mapping Project

In collaboration with the health ministries that we serve and other partners, we set out to complete the multiple-country Global Trachoma Mapping Project. To maximize the accuracy and reliability of its outputs, we needed in-built, practical mechanisms for quality assurance and quality control. This article describes how those mechanisms were created and deployed. Using expert opinion, computer simulation, working groups, field trials, progressively accumulated in-project experience, and external evaluations, we developed 1) criteria for where and where not to undertake population-based prevalence surveys for trachoma; 2) three iterations of a standardized training and certification system for field teams; 3) a customized Android phone–based data collection app; 4) comprehensive support systems; and 5) a secure end-to-end pipeline for data upload, storage, cleaning by objective data managers, analysis, health ministry review and approval, and online display. We are now supporting peer-reviewed publication. Our experience shows that it is possible to quality control and quality assure prevalence surveys in such a way as to maximize comparability of prevalence estimates between countries and permit high-speed, high-fidelity data processing and storage, while protecting the interests of health ministries.

Impact Survey Results after SAFE Strategy Implementation in 15 Local Government Areas of Kebbi, Sokoto and Zamfara States, Nigeria

Purpose: To determine prevalence of trachoma after interventions in 15 local government areas (LGAs) of Kebbi, Sokoto and Zamfara States, Nigeria.

Methods: A population-based impact survey was conducted in each LGA using Global Trachoma Mapping Project (GTMP) protocols. In each LGA, 25 villages were selected, except in Arewa LGA, where we selected 25 villages from each of four subunits to obtain finer-resolution prevalence information. Villages were selected with probability proportional to size. In each village, 25 households were enrolled and all consenting residents aged ≥1 year were examined by GTMP-certified graders for trachomatous inflammation—follicular (TF) and trachomatous trichiasis (TT). Information on sources of household water and types of sanitation facilities used was collected through questioning and direct observation.

Results: The number of households enrolled per LGA ranged from 623 (Kware and Tangaza) to 2488 (Arewa). There have been marked reductions in the prevalence of TF and TT since baseline surveys were conducted in all 15 LGAs. Eight of the 15 LGAs have attained TF prevalences <5% in children, while 10 LGAs have attained TT prevalences <0.2% in persons aged ≥15 years. Between 49% and 96% of households had access to water for hygiene purposes within 1 km of the household, while only 10–59% had access to improved sanitation facilities.

Conclusion: Progress towards elimination of trachoma has been made in these 15 LGAs. Collaboration with water and sanitation agencies and community-based trichiasis surgery are still needed in order to eliminate trachoma by the year 2020.

Strengthening the links between mapping, planning and global engagement for disease elimination: lessons learnt from trachoma

BACKGROUND

Trachoma is the leading infectious cause of blindness. Until recently, reliable data on the global extent of the disease, detailed plans for elimination, and government, donor and partner engagement were all inadequate.

METHODS

The trachoma community undertook a systematic, three-pronged strategy to map trachoma district by district, develop national-level trachoma elimination plans, and create a framework for governments, donors and partners to convene and coordinate in support of trachoma elimination.  RESULT: There has been a frame-shift in internal and external perceptions of the global trachoma programme, from being an effort working towards disease control in focussed geographical areas, to one in the process of achieving worldwide disease elimination. Multiple factors contributed to the successful implementation of mapping, planning, and cross-sectional engagement of governments, partners and donors.

CONCLUSIONS

Elimination of trachoma is possible if the right combination of factors is in place. Planning for success is a critical first step. Some remaining challenges must still be addressed if the elimination targets are to be successfully attained.

A diagnostic instrument to help field graders evaluate active trachoma

The SAFE strategy (Surgery for trichiasis, mass treatment with Antibiotics to clear ocular Chlamydia trachomatis infection, and Facial cleanliness and Environmental improvement to reduce transmission) is being used to eliminate trachoma as a public health problem. Decisions on whether or not to implement the A, F, and E components of SAFE are made on the basis of the prevalence of trachomatous inflammation-follicular (TF) in 1-9-year-olds. TF has a precise definition: at least five follicles, each of which is at least 0.5-mm diameter, in the central part of the upper tarsal conjunctiva. Determining whether a follicle has a diameter ≥0.5mm is difficult using magnifying loupes alone. We have developed an ultra-low-cost solution: a follicle size guide that takes the form of a durable printed adhesive sticker which can be fixed to graders' thumb nails for direct size comparison. This tool will be made available to health ministries free of charge. It is anticipated to simplify grader training, increase grader trainee pass rates, and prevent in-service diagnostic drift after training is complete.

The cost of mapping trachoma: Data from the Global Trachoma Mapping Project

Background

The Global Trachoma Mapping Project (GTMP) was implemented with the aim of completing the baseline map of trachoma globally. Over 2.6 million people were examined in 1,546 districts across 29 countries between December 2012 and January 2016. The aim of the analysis was to estimate the unit cost and to identify the key cost drivers of trachoma prevalence surveys conducted as part of GTMP.

Methodology and principal findings

In-country and global support costs were obtained using GTMP financial records. In-country expenditure was analysed for 1,164 districts across 17 countries. The mean survey cost was $13,113 per district [median: $11,675; IQR = $8,365-$14,618], $17,566 per evaluation unit [median: $15,839; IQR = $10,773-$19,915], $692 per cluster [median: $625; IQR = $452-$847] and $6.0 per person screened [median: $4.9; IQR = $3.7-$7.9]. Survey unit costs varied substantially across settings, and were driven by parameters such as geographic location, demographic characteristics, seasonal effects, and local operational constraints. Analysis by activities showed that fieldwork constituted the largest share of in-country survey costs (74%), followed by training of survey teams (11%). The main drivers of in-country survey costs were personnel (49%) and transportation (44%). Global support expenditure for all surveyed districts amounted to $5.1m, which included grant management, epidemiological support, and data stewardship.

Conclusion

This study provides the most extensive analysis of the cost of conducting trachoma prevalence surveys to date. The findings can aid planning and budgeting for future trachoma surveys required to measure the impact of trachoma elimination activities. Furthermore, the results of this study can also be used as a cost basis for other disease mapping programmes, where disease or context-specific survey cost data are not available.

There are currently few data sets available to aid programmes in planning and budgeting for population-based surveys in low- and middle- income countries. With the objective of identifying cost drivers and key variables influencing prevalence survey costs, the authors collected expenses incurred during the Global Trachoma Mapping Project (GTMP) which surveyed 2.6 million people across 29 countries. Expenditure from surveying 1,164 districts in 17 countries was analysed. Our results showed that the majority of in-country expenditure was spent on personnel (per diems, accommodation, meals and beverages) (49%) and local transportation (44%) and that the median survey expenditure was US$11,675 per district (or US$15,839 per evaluation unit, US$625 per cluster and US$4.9 per person examined). There were large variations in survey unit costs across settings, based on local geographic, demographic, seasonal effects and local operational characteristics. In addition, the resources required for the global support and coordination of the GTMP were analysed and amounted to US$5.1m (US$3,318 per district or US$5,668 per EU). Global support expenses can be substantial for a large multi-country mapping exercise conducted in a limited period of time such as the GTMP. Findings from this study can be used to inform other disease mapping projects, and to inform planning and budgeting for the prevalence surveys that will assess the impact of trachoma elimination interventions.

The Burden of and Risk Factors for Trachoma in Selected Districts of Zimbabwe: Results of 16 Population-Based Prevalence Surveys

Background: Trachoma, a leading cause of blindness, is targeted for global elimination as a public health problem by 2020. In order to contribute to this goal, countries should demonstrate reduction of disease prevalence below specified thresholds, after implementation of the SAFE strategy in areas with defined endemicity. Zimbabwe had not yet generated data on trachoma endemicity and no specific interventions against trachoma have yet been implemented.

Methods: Two trachoma mapping phases were successively implemented in Zimbabwe, with eight districts included in each phase, in September 2014 and October 2015. The methodology of the Global Trachoma Mapping Project was used.

Results: Our teams examined 53,211 people for trachoma in 385 sampled clusters. Of 18,196 children aged 1–9 years examined, 1526 (8.4%) had trachomatous inflammation–follicular (TF). Trichiasis was observed in 299 (1.0%) of 29,519 people aged ≥15 years. Of the 16 districts surveyed, 11 (69%) had TF prevalences ≥10% in 1–9-year-olds, indicative of active trachoma being a significant public health problem, requiring implementation of the A, F and E components of the SAFE strategy for at least 3 years. The total estimated trichiasis backlog across the 16 districts was 5506 people. The highest estimated trichiasis burdens were in Binga district (1211 people) and Gokwe North (854 people).

Conclusion: Implementation of the SAFE strategy is needed in parts of Zimbabwe. In addition, Zimbabwe needs to conduct more baseline trachoma mapping in districts adjacent to those identified here as having a public health problem from the disease.