Mapping the global distribution of trachoma: why an updated atlas is needed

The simplified trachoma grading system, amended

A simplified grading system for trachoma was published by the World Health Organization (WHO) in 1987. Intended for use by non-specialist personnel working at community level, the system includes five signs, each of which can be present or absent in any eye: (i) trachomatous trichiasis; (ii) corneal opacity; (iii) trachomatous inflammation—follicular; (iv) trachomatous inflammation—intense; and (v) trachomatous scarring. Though neither perfectly sensitive nor perfectly specific for trachoma, these signs have been essential tools for identifying populations that need interventions to eliminate trachoma as a public health problem. In 2018, at WHO’s 4th global scientific meeting on trachoma, the definition of one of the signs, trachomatous trichiasis, was amended to exclude trichiasis that affects only the lower eyelid. This paper presents the amended system, updates its presentation, offers notes on its use and identifies areas of ongoing debate.

Prevalence of Trachoma in Kogi State, Nigeria: Results of four Local Government Area-Level Surveys from the Global Trachoma Mapping Project

PURPOSE

To determine the prevalence of trachoma in four Local Government Areas (LGAs) of Kogi State, Nigeria.

METHODS

In June 2014, we conducted population-based, cross-sectional surveys according to Global Trachoma Mapping Project (GTMP) protocols in selected LGAs of Kogi State. In each LGA, 25 clusters were selected with probability proportional to size. In each of these clusters, 25 households were enrolled for the survey. All residents of selected households aged ≥1 year were examined by GTMP-certified graders for trachomatous inflammation-follicular (TF) and trichiasis using the simplified trachoma grading scheme. Data on sources of household water and types of sanitation facilities were collected through questioning and direct observation.

RESULTS

The age-adjusted TF prevalence in 1-9-year-olds ranged from 0.4% (95% CI 0.1-0.8%) in Bassa to 1.0% (95% CI 0.3-1.9%) in Omala. Across all four LGAs, only one case of trichiasis was found; this individual was in Omala, giving that LGA a trichiasis prevalence in individuals aged ≥15 years of 0.02% (95% CI 0.00-0.07%). Between 77 and 88% of households had access to water for hygiene purposes, while only 10-30% had access to improved sanitation facilities.

CONCLUSION

Trachoma is not a public health problem in any of the 4 LGAs surveyed. There is, however, the need to increase access to adequate water and sanitation services to contribute to the health and social and economic well-being of these communities.

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. In each of the 32 evaluation units (EUs), we selected 31 households in each of 24 clusters. In selected households, trained, certified graders examined all residents aged 1 year and above for evidence of trachomatous inflammation—follicular (TF) and trichiasis. In eyes that had trichiasis, the presence or absence of trachomatous scarring (TS) was recorded, and the subject was asked about previous trichiasis management recommendations from health workers.

Results: Five EUs (encompassing seven administrative districts) had prevalence estimates of trichiasis+TS unknown to the health system in ≥15-year-olds of ≥0.2%, and require public-health-level implementation of trichiasis surgery services. Eleven EUs (encompassing 16 administrative districts) had TF prevalence estimates in 1–9-year-olds of ≥5%. Intervention with the A, F and E components of the SAFE strategy for trachoma elimination is required for nearly 1.5 million people.

Conclusion: Trachoma is a public health problem in some parts of Zambia. The Ministry of Health will continue to partner with other stakeholders to implement the multi-sectoral SAFE strategy. Consideration should be given to re-surveying other suspected-endemic administrative districts in which surveys using older methodologies returned TF prevalence estimates ≥5%.

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. A total of 5582 adults aged ≥15 years living in the same households were examined for trachomatous trichiasis (TT). Household-level access to water and sanitation was recorded.

RESULTS

Three of four marakez had age-adjusted TF prevalence estimates in 1-9-year olds of >10%; the other markaz had a TF prevalence estimate of 5-9.9%. Estimates of the age- and gender-adjusted prevalence of unmanaged TT in adults ranged from 0.7% to 2.3%. Household-level access to water and sanitation was high. (We did not, however, measure use of water or sanitation facilities.) Conclusions: Each of the four marakez surveyed has trachoma as a public health problem, with a need for implementation of the SAFE (surgery, antibiotics, facial cleanliness, environmental improvement) strategy. Further mapping is also required to determine the need for interventions in other areas of Egypt.

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. Fieldwork was undertaken from September 2013 to March 2015. Risk factors for TF in children aged 1–9 years were evaluated using multilevel random effects logistic regression.

Results: The TF prevalence in children aged 1–9 years was ≥10% in two EUs (7 districts) and 5–9.9% in six EUs (24 districts). In adults aged ≥15 years, trichiasis prevalence was ≥0.2% in five EUs (19 districts). Being older (within the 1–9-year age bracket), being male, living in a household with higher numbers of children, and living in a household that reported the use of open defecation, were each independently associated with higher odds of TF.

Conclusions: These surveys provided baseline data to enable planning for trachoma elimination. The World Health Organization Alliance for the Global Elimination of Trachoma by 2020 stands ready to assist Yemen once security considerations permit further surveys and implementation of control activities.

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.

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. In each EU, the goal was to examine at least 1019 children aged 1-9 years by recruiting 649 households; all consenting residents aged ≥ 1 year living in those households were examined. Each participant was examined for trachomatous inflammation-follicular (TF), trachomatous inflammation-intense (TI), and trichiasis.

RESULTS

Two EUs had data that could not be validated, and were excluded from the analysis. GPS data for three other pairs of EUs suggested that EU divisions were inaccurate; data for each pair were combined within the pair. In the 41 resulting EUs, 29,924 households in 967 clusters were visited, and 104,584 people were examined. The age-adjusted EU-level prevalence of TF in 1-9-year-olds ranged from 0.0% to 23.3%, and the age- and gender-adjusted EU-level prevalence of trichiasis in ≥ 15-year-olds ranged from 0.02% to 1.3%. TF was above the WHO elimination threshold in 16 EUs (39%) and trichiasis was above the WHO elimination threshold in 29 EUs (71%). Women had a higher prevalence of trichiasis than did men in 31 EUs (76%). A higher ratio of trichiasis prevalence in women to trichiasis prevalence in men was associated (p = 0.03) with a higher prevalence of trichiasis at EU level.

CONCLUSION

Public health-level interventions against trachoma are needed in Chad. Over 10,000 people need management of their trichiasis; women account for about two-thirds of this total. The association between a higher ratio of trichiasis prevalence in women to that in men with higher overall trichiasis prevalence needs further investigation.

Completing Baseline Mapping of Trachoma in Nepal: Results of 27 Population-Based Prevalence Surveys Conducted in 2013 and 2014

PURPOSE

Trachoma is endemic in parts of Nepal; implementation of the surgery, antibiotics, facial cleanliness, environmental improvement (SAFE) strategy started in 2002. Some suspected-endemic districts had not previously been mapped. We aimed to estimate the prevalences of trachomatous inflammation-follicular (TF) and trichiasis in those districts.

METHODS

Population-based prevalence surveys were undertaken in 27 districts. In each of those districts, two-stage cluster sampling was used to select a sample of 2000 children aged 1-9 years and 4000 adults aged ≥15 years from a total of 40 wards (clusters), drawn evenly from two subdistricts. Consenting eligible participants were examined for trachoma by Global Trachoma Mapping Project (GTMP)-certified graders, using the World Health Organization simplified grading system. Data were analyzed at district level using GTMP methods.

RESULTS

A total of 43,200 households were surveyed, and 162,094 people were examined for trachoma. District-level TF prevalence in 1-9-year-olds ranged from 0% to 4.3% (95% confidence interval [CI] 2.4-6.2). Among adults aged ≥15 years, trichiasis prevalence ranged from 0% to 0.33% (95% CI 0.08-0.65).

CONCLUSION

TF was not a public health problem in any of the 27 districts surveyed; thus, antibiotic mass drug administration is not needed. In two districts (Dhanusa and Gorkha), trichiasis prevalence in adults aged ≥15 years was ≥0.2%; thus, further trichiasis surgery interventions at public health level are warranted to achieve elimination. These findings will facilitate planning for elimination of trachoma as a public health problem in Nepal.

Prevalence of Trachoma and Access to Water and Sanitation in Benue State, Nigeria: Results of 23 Population-Based Prevalence Surveys

PURPOSE

We sought to determine the prevalence of trachoma in each local government area (LGA) of Benue State, Nigeria.

METHODS

Two-stage cluster sampling was used to conduct a series of 23 population-based prevalence surveys. LGAs were the evaluation units surveyed. In each LGA, 25 households were selected in each of 25 clusters, and individuals aged 1 year and above resident in those households were invited to be examined for trachoma. Data on access to water and sanitation were also collected at household level.

RESULTS

A total of 91,888 people were examined from among 93,636 registered residents across the 23 LGAs. The LGA-level prevalence of trachomatous inflammation-follicular (TF) in 1-9 year olds ranged from 0.3% to 5.3%. Two LGAs had TF prevalences of 5.0-9.9%. The LGA-level prevalence of trichiasis in ≥15-year-olds ranged from 0.0% to 0.35%. Access to improved drinking water sources ranged from 0% in Gwer West to 99% in Tarka, while access to improved sanitation ranged from 1% in Gwer West to 92% in Oturkpo.

CONCLUSION

There is a need for public health-level interventions against trachoma in three LGAs of Benue State.

Prevalence of trachoma in the area councils of the Federal Capital Territory, Nigeria: results of six population-based surveys

PURPOSE

The World Health Organization's (WHO's) global trachoma elimination programme recommends mapping of trachoma at district level for planning of elimination activities in affected populations. This study aimed to provide data on trachoma prevalence for the Area Councils of Nigeria's Federal Capital Territory (FCT).

METHODS

Using the Global Trachoma Mapping Project (GTMP) protocols, in March and April 2014, we conducted a population-based cross-sectional survey in each of the six Area Councils of FCT. Signs were defined based on the WHO simplified grading scheme.

RESULTS

98% to 100% of the targeted households were enrolled in each Area Council. The number of children aged 1-9 years examined per Area Council ranged from 867 to 1248. The number of persons aged ≥15 years examined ranged from 1302 to 1836. The age-adjusted prevalence of trachomatous inflammation-follicular in 1-9-year-olds was <5% in each Area Council. The age- and gender-adjusted prevalence of trichiasis in those aged ≥15 years ranged from 0.0% to 0.3%; two Area Councils (Gwagwalada and Kwali) had prevalences above the 0.2% elimination threshold. The proportion of households with access to improved latrines and water sources ranged from 17 to 90% and 39 to 85% respectively.

CONCLUSIONS

Gwagwalada and Kwali Area Councils need to perform more trichiasis surgeries to attain the trichiasis elimination prevalence target of 0.2% in persons aged ≥15 years. No Area Council requires mass antibiotic administration for the purposes of trachoma's elimination as a public health problem. All Area Councils need to accelerate provision of access to improved water sources and latrine facilities, to achieve universal coverage.

Global epidemiology of podoconiosis: A systematic review

Background

Podoconiosis is one of the few diseases that could potentially be eliminated within one generation. Nonetheless, the global distribution of the disease remains largely unknown. The global atlas of podoconiosis was conceived to define the epidemiology and distribution of podoconiosis through dedicated surveys and assembling the available epidemiological data.

Methods

We have synthesized the published literature on the epidemiology of podoconiosis. Through systematic searches in SCOPUS and MEDLINE from inception to February 14, 2018, we identified observational and population-based studies reporting podoconiosis. To establish existence of podoconiosis, we used case reports and presence data. For a study to be included in the prevalence synthesis, it needed to be a population-based survey that involved all residents within a specific area. Studies that did not report original data were excluded. We undertook descriptive analyses of the extracted data. This study is registered with PROSPERO, number CRD42018084959.

Results

We identified 3,260 records, of which 27 studies met the inclusion criteria. Podoconiosis was described to exist or be endemic in 32 countries, 18 from the African Region, 3 from Asia and 11 from Latin America. Overall, podoconiosis prevalence ranged from 0·10% to 8.08%, was highest in the African region, and was substantially higher in adults than in children and adolescents. The highest reported prevalence values were in Africa (8.08% in Cameroon, 7.45% in Ethiopia, 4.52% in Uganda, 3.87% in Kenya and 2.51% in Tanzania). In India, a single prevalence of 0.21% was recorded from Manipur, Mizoram and Rajasthan states. None of the Latin American countries reported prevalence data.

Conclusion

Our data suggest that podoconiosis is more widespread in the African Region than in the rest of the regions, although this could be related to the fact that most podoconiosis epidemiological research has been focused in the African continent. The assembled dataset confirms that comprehensive podoconiosis control strategies such as promotion of footwear and personal hygiene are urgently needed in endemic parts of Africa. Mapping, active surveillance and a systematic approach to the monitoring of disease burden must accompany the implementation of podoconiosis control activities.

Podoconiosis is one of the Neglected Tropical Diseases, and causes painful and massive swelling of the lower legs. Despite the importance of the disease, its global distribution and epidemiology are poorly understood. We conducted a systematic review to assess the global epidemiology of podoconiosis. We found that podoconiosis was described to exist or be endemic in 32 countries, 18 from Africa, 3 from Asia and 11 from Latin America. Almost all prevalence data recorded corresponded to the African region. None of the Latin American countries reported prevalence data, although some countries are suspected to be endemic. We recommend that comprehensive podoconiosis control strategies such as promotion of footwear and personal hygiene are urgently needed in endemic countries in the African Region. Mapping, active surveillance and a systematic approach to the monitoring of disease burden must accompany the implementation of podoconiosis control activities.

Spatial clustering of high load ocular Chlamydia trachomatis infection in trachoma: a cross-sectional population-based study

Chlamydia trachomatis (Ct) is the most common cause of bacterial sexually transmitted infection and infectious cause of blindness (trachoma) worldwide. Understanding the spatial distribution of Ct infection may enable us to identify populations at risk and improve our understanding of Ct transmission. In this study, we sought to investigate the spatial distribution of Ct infection and the clinical features associated with high Ct load in trachoma-endemic communities on the Bijagós Archipelago (Guinea Bissau). We collected 1507 conjunctival samples and corresponding detailed clinical data during a cross-sectional population-based geospatially representative trachoma survey. We used droplet digital PCR to estimate Ct load on conjunctival swabs. Geostatistical tools were used to investigate clustering of ocular Ct infections. Spatial clusters (independent of age and gender) of individuals with high Ct loads were identified using local indicators of spatial association. We did not detect clustering of individuals with low load infections. These data suggest that infections with high bacterial load may be important in Ct transmission. These geospatial tools may be useful in the study of ocular Ct transmission dynamics and as part of trachoma surveillance post-treatment, to identify clusters of infection and thresholds of Ct load that may be important foci of re-emergent infection in communities.

Burden of trachoma in five counties of Eastern Equatoria state, South Sudan: Results from population-based surveys

BACKGROUND

In order to decrease the prevalence of trachoma within the country, the Republic of South Sudan has implemented components of the SAFE strategy in various counties since 2001. Five counties in Eastern Equatoria state were surveyed in order to monitor progress of programmatic interventions and determine if additional rounds of Mass Drug Administration with azithromycin were needed.

METHODOLOGY/ PRINCIPAL FINDINGS

Five counties (Budi, Lafon, Kapoeta East, Kapoeta South and Kapoeta North) were surveyed from April to October 2015. A cross-sectional, multi-stage, cluster-random sampling was used. All present, consenting residents of selected households were examined for all clinical signs of trachoma using the World Health Organization (WHO) simplified grading system. 14,462 individuals from 3,446 households were surveyed. The prevalence of trachomatous inflammation-follicular (TF) in children ages one to nine years ranged from 17.4% (95% Confidence Interval (CI): 11.4%, 25.6%) in Budi county to 47.6%, (95% CI: 42.3%, 53.0%) in Kapoeta East county. Trachomatous trichiasis (TT) was also highly prevalent in those 15 years and older, ranging between 2.6% (95% CI: 1.6%, 4.0%) in Kapoeta South to 3.9% (95% CI: 2.4%, 6.1%) in Lafon. The presence of water and sanitation were low in all five counties, including two counties which had a complete absence of latrines in all surveyed clusters.

CONCLUSIONS/ SIGNIFICANCE

To our knowledge, these were the first trachoma surveys conducted in the Republic of South Sudan since their independence in 2011. The results show that despite years of interventions, four of the five surveyed counties require a minimum of five additional years of SAFE strategy implementation, with the fifth requiring at minimum three more years.

Preventing Long-Term Ocular Complications of Trachoma With Topical Azithromycin: A 3-Year Follow-up Study

PURPOSE

To determine the role of a single cycle of topical azithromycin in preventing long-term trachoma complications in children from an area with endemic trachoma.

DESIGN

A longitudinal cohort study.

METHODS

Two hundred thirty-eight (n = 238) children with active trachoma were enrolled in the current study. They were aged 1 to 10 years, with trachomatous inflammation based on the simplified World Health Organization grading system. These children were identified out of a survey of 8600 children from 7 villages in Punjab, Pakistan, where trachoma was endemic. The studied patients with active trachoma were treated with a single regimen of azithromycin 1.5% eye drops, given twice daily for 3 days, and were followed up for 3 years. The long-term effects of this therapy were documented for the first time in an endemic area.

RESULTS

Two hundred fourteen children (90%) were present at 1-year follow-up with 10% dropout, and 178 (75%) were present at 3-year follow-up with 25% dropout. Of these, 23% and 11% had active trachoma at 1 and 3 years, respectively. Active trachoma was minimized from 100% at baseline to 11% at the end of 3 years. The reinfection rate was 4%. None of the patients developed trachoma-related ocular complications during the study period.

CONCLUSIONS

A single cycle of topical azithromycin can be used as an effective and safe option for treating active trachoma in children in endemic areas. This study also documented that a single cycle of topical azithromycin prevents trachoma-related ocular complications in an endemic area.

Mapping Trachoma in Kaduna State, Nigeria: Results of 23 Local Government Area-Level, Population-Based Prevalence Surveys

INTRODUCTION

To prepare for global elimination of trachoma by 2020, the World Health Organization (WHO) recommends mapping of trachoma at district-level to enable planning of elimination activities in affected populations. The aim of our study was to provide data on trachoma for each local government area (LGA) of Kaduna State, Nigeria, as such data were previously unavailable.

METHOD

As part of the Global Trachoma Mapping Project (GTMP), a population-based cross-sectional trachoma survey was conducted in each of the 23 LGAs of Kaduna State, between May and June 2013. The protocols of the GTMP were used.

RESULTS

The prevalence of trachomatous inflammation - follicular (TF) in children aged 1-9 years was between 0.03% and 8% across the LGAs, with only one LGA (Igabi) having a TF prevalence ≥5%. The LGA-level prevalences of trichiasis in persons aged 15 years and older were between 0.00% and 0.78%. Eleven LGAs had trichiasis prevalences of 0.2% and over in adults; a threshold equivalent to 1 case per 1000 total population. The LGA-level proportion of households with access to improved water sources ranged from 9% to 96%, while household access to latrines ranged from 5% to 99%.

CONCLUSION

Kaduna State has generally hypoendemic trachoma, but a few trichiasis surgeries are still required to attain the WHO elimination targets. Better access to improved water and sanitation is needed.

Perspectives of National Coordinators and Partners on the Work of the Global Trachoma Mapping Project

Purpose

Neglected tropical diseases (NTDs) affect people living in the poorest regions of the world and their debilitating effects perpetuate the poverty cycle. Understanding the distribution of NTDs is crucial for effective intervention delivery. In 2012, the Global Trachoma Mapping Project (GTMP) was initiated to map >1800 suspected trachoma endemic districts by March 2015. This research was carried out to better understand the implementation experience and identify lessons which might inform the GTMP and similar initiatives.

Methods

Using grounded theory methodology, semi-structured interviews were conducted with key informants from six countries with 63% of the global mapping backlog (Ethiopia, Malawi, Mozambique, Nigeria, Solomon Islands, and Yemen). Interviews were transcribed, coded, and findings separated into categories.

Results

Three themes were identified during the research; planning and operations, technical implementation, and governance. The project was felt to be most successful in countries where the Ministry of Health was actively engaged in setting standards, ensuring capacity building for government staff, and guiding the training, data collection, analysis, and interpretation of data. Standardized tools, training platforms, and the use of electronic data capture increased confidence in the reliability of the survey data, informed quality improvement efforts within survey implementation, and the immediate release of results empowered end-user decision-makers. Regional collaboration between endemic countries bolstered program manager competence and confidence, while reinforcing partnerships essential to the success of the GTMP.

Conclusions

We depict how innovative characteristics of the GTMP, and lessons learned from its implementation, can strengthen similar initiatives to map disease prevalence and risk factors.

Completion of Baseline Trachoma Mapping in Malawi: Results of Eight Population-Based Prevalence Surveys Conducted with the Global Trachoma Mapping Project

Purpose: Following a first phase of trachoma mapping in Malawi with the Global Trachoma Mapping Project, we identified and mapped trachoma districts previously suspected to be non-endemic, although adjacent to districts with estimated trachoma prevalences indicating a public health problem.

Methods: We conducted population-based surveys in eight evaluation units (EUs) comprising eight districts in Malawi (total population 3,230,272). A 2-stage cluster random sampling design allowed us to select 30 households from each of 30 clusters per EU; all residents aged 1 year and older in selected households were examined for evidence of trachomatous inflammation–follicular (TF) and trachomatous trichiasis (TT).

Results: None of the eight EUs had a TF prevalence in 1–9-year-olds ≥10%, one district (Dedza) had a TF prevalence between 5.0% and 9.9%, and only one district (Karonga) had a trichiasis prevalence in adults ≥0.2%.

Conclusion: The prevalence of TF and TT in six of eight EUs surveyed was consistent with an original categorization of trachoma being unlikely to be a public health problem. In the absence of formal surveys, health management information system data and other locally available information about trachoma is likely to be useful in predicting areas where public health interventions against trachoma are required.

The Global Trachoma Mapping Project: Methodology of a 34-Country Population-Based Study

Purpose: To complete the baseline trachoma map worldwide by conducting population-based surveys in an estimated 1238 suspected endemic districts of 34 countries.

Methods: A series of national and sub-national projects owned, managed and staffed by ministries of health, conduct house-to-house cluster random sample surveys in evaluation units, which generally correspond to “health district” size: populations of 100,000–250,000 people. In each evaluation unit, we invite all residents aged 1 year and older from h households in each of c clusters to be examined for clinical signs of trachoma, where h is the number of households that can be seen by 1 team in 1 day, and the product h × c is calculated to facilitate recruitment of 1019 children aged 1–9 years. In addition to individual-level demographic and clinical data, household-level water, sanitation and hygiene data are entered into the purpose-built LINKS application on Android smartphones, transmitted to the Cloud, and cleaned, analyzed and ministry-of-health-approved via a secure web-based portal. The main outcome measures are the evaluation unit-level prevalence of follicular trachoma in children aged 1–9 years, prevalence of trachomatous trichiasis in adults aged 15 + years, percentage of households using safe methods for disposal of human feces, and percentage of households with proximate access to water for personal hygiene purposes.

Results: In the first year of fieldwork, 347 field teams commenced work in 21 projects in 7 countries.

Conclusion: With an approach that is innovative in design and scale, we aim to complete baseline mapping of trachoma throughout the world in 2015.

Baseline Trachoma Mapping in Malawi with the Global Trachoma Mapping Project (GTMP)

Purpose: To determine the prevalence of trachoma in all suspected endemic districts in Malawi.

Methods: A population-based survey conducted in 16 evaluation units from 12 suspected endemic districts in Malawi (population 6,390,517), using the standardized Global Trachoma Mapping Project (GTMP) protocol. A 2-stage cluster-random sampling design selected 30 households from each of 30 clusters per evaluation unit; all residents aged 1 year and older in selected households were examined for evidence of follicular trachoma (TF), intense trachomatous inflammation (TI), and trachomatous trichiasis (TT).

Results: Four of the 16 evaluation units were found to be endemic for trachoma, with a prevalence range of 10.0–13.5% for TF and 0.2–0.6% for TT. Nine evaluation units had a TF prevalence between 5.0% and 9.9% while three evaluation units had a TF prevalence <5.0%.

Conclusion: The prevalence rates of active trachoma in Malawi were not uniform among suspected endemic evaluation units, with rates higher than the World Health Organization (WHO) threshold for implementation of community-based control measures (TF ≥ 10.0%) in only 4 of the 16 evaluation units. Trachoma remains a disease of public health importance in some parts of Malawi and adjoining (unmapped) districts should be prioritized for mapping. According to the survey, an additional 3,169,362 people require intervention to reduce active disease and 1557 trichiasis surgeries are needed to reduce the prevalence of TT below WHO recommended thresholds.

The impact of climate on the abundance of Musca sorbens, the vector of trachoma

BACKGROUND

To assess the extent to which climate may affect the abundance of Musca sorbens, a putative vector of trachoma.

DATA SOURCES

Studies were identified by systematically searching online databases including CAB abstracts, Embase, Global Health, Medline, Web of Science and BIOS Online, references from key articles, and the websites of relevant international agencies.

METHODS

A systematic literature review was conducted of field and laboratory studies that reported the impact of climate factors (e.g., temperature, humidity) on the synanthropic fly Musca sorbens. Data were systematically extracted and studies assessed for quality by two readers. Study results were reported narratively.

RESULTS

A total of 16 studies met the inclusion criteria but only three evaluated associations between climatic/abiotic factors and M. sorbens. Limited evidence indicates that M. sorbens abundance has an optimal temperature and humidity range. Thirteen studies reported seasonal patterns but no consistent pattern was found between season and the abundance of M. sorbens.

CONCLUSIONS

The evidence base regarding the effect of climatic factors on M. sorbens is limited, so it is difficult to construct a biological model driven by climate for this species. A multivariate statistical approach based on the climate of sites where M. sorbens is found may better capture its complex relationship with climatic factors as well as aid in mapping the global range of M. sorbens.

Short-term Forecasting of the Prevalence of Trachoma: Expert Opinion, Statistical Regression, versus Transmission Models

Background

Trachoma programs rely on guidelines made in large part using expert opinion of what will happen with and without intervention. Large community-randomized trials offer an opportunity to actually compare forecasting methods in a masked fashion.

Methods

The Program for the Rapid Elimination of Trachoma trials estimated longitudinal prevalence of ocular chlamydial infection from 24 communities treated annually with mass azithromycin. Given antibiotic coverage and biannual assessments from baseline through 30 months, forecasts of the prevalence of infection in each of the 24 communities at 36 months were made by three methods: the sum of 15 experts’ opinion, statistical regression of the square-root-transformed prevalence, and a stochastic hidden Markov model of infection transmission (Susceptible-Infectious-Susceptible, or SIS model). All forecasters were masked to the 36-month results and to the other forecasts. Forecasts of the 24 communities were scored by the likelihood of the observed results and compared using Wilcoxon’s signed-rank statistic.

Findings

Regression and SIS hidden Markov models had significantly better likelihood than community expert opinion (p = 0.004 and p = 0.01, respectively). All forecasts scored better when perturbed to decrease Fisher’s information. Each individual expert’s forecast was poorer than the sum of experts.

Interpretation

Regression and SIS models performed significantly better than expert opinion, although all forecasts were overly confident. Further model refinements may score better, although would need to be tested and compared in new masked studies. Construction of guidelines that rely on forecasting future prevalence could consider use of mathematical and statistical models.

Forecasts of infectious diseases are rarely made in a falsifiable manner. Trachoma trials offer an opportunity to actually compare forecasting methods in a masked fashion. The World Health Organization recommends at least three annual antibiotic mass drug administrations where the prevalence of trachoma is greater than 10% in children aged 1–9 years, with coverage at least at 80%. The Program for the Rapid Elimination of Trachoma trials estimated longitudinal prevalence of ocular chlamydial infection from 24 communities treated annually with mass azithromycin. Here, we compared forecasts of the prevalence of infection in each of the 24 communities at 36 months (given antibiotic coverage and biannual assessments from baseline through 30 months, and masked to the 36-month assessments) made by experts, statistical regression, and a transmission model. The transmission model was better than regression, with both far better than experts’ opinion. Construction of guidelines that rely on forecasting future prevalence could consider use of mathematical and statistical models.

Short term outcome of anterior lamellar reposition in treating trachomatous trichiasis

Purpose. To evaluate the outcome of anterior lamellar reposition (ALR) in treating trachomatous trichiasis. Methods. Patients with trachomatous trichiasis or entropion with short tarsus were treated by ALR between February 2009 and November 2013. This included splitting of the lid margin behind the aberrant lash line to separate the lid lamellae. The anterior lamella was recessed and fixated using 4/0 silk sutures. The extra lashes and their routes were excised. Sutures were removed by the 3rd week and patients completed 6 months of follow-up. Recurrence of ≤5 lashes was treated by electrolysis. Results. The study included 752 eyelids (445 patients; 58.4% females, 41.6% males), mean age 53.2 ± 6.9 y. 179 (25.1%) lids had entropion while 287 (64.5%) patients had corneal affection. By the third week, 2.66% lid had trichiasis while 30.8% had no rubbing lashes. By the 6th month, 14.9% of lids showed recurrence while 66.1% were completely cured (CI = 0.63–0.69) and 19% had partial success (CI = 0.16–0.21). Abnormal lid appearance persisted in 2.66% and 12.9% required another surgery. Conclusion. ALR is a good option for treating trachomatous trichiasis especially without cicatricial entropion. Excision of dysplastic lashes is thought to augment the surgical outcome.

Addressing healthy aging populations in developing countries: unlocking the opportunity of eHealth and mHealth

Aging societies worldwide propose a significant challenge to the model and organisation of the delivery of healthcare services. In developing countries, communicable and non-communicable diseases are affecting how the ageing population access healthcare; this could be due to varying reasons such as geographical barriers, limited financial support and poor literacy. New information and communication technology, such as eHealth have the potential to improve access to healthcare, information exchange and improving public and personalised medicine for elderly groups. In this article we will first frame the context of information and communication technologies in light of an aging landscape. We will also discuss the problems related to implementing the needed infrastructure for uptake of new technology, with particular emphasis on developing countries. In so doing, we highlight areas where newer technologies can serve as promising tools or vehicles to address health and healthcare-related gaps and needs of elderly people living in resource-constrained settings.

Surveillance systems for neglected tropical diseases: global lessons from China's evolving schistosomiasis reporting systems, 1949-2014

Though it has been a focus of the country’s public health surveillance systems since the 1950s, schistosomiasis represents an ongoing public health challenge in China. Parallel, schistosomiasis-specific surveillance systems have been essential to China’s decades-long campaign to reduce the prevalence of the disease, and have contributed to the successful elimination in five of China’s twelve historically endemic provinces, and to the achievement of morbidity and transmission control in the other seven. More recently, an ambitious goal of achieving nation-wide transmission interruption by 2020 has been proposed. This paper details how schistosomiasis surveillance systems have been structured and restructured within China’s evolving public health system, and how parallel surveillance activities have provided an information system that has been integral to the characterization of, response to, and control of the disease. With the ongoing threat of re-emergence of schistosomiasis in areas previously considered to have achieved transmission control, a critical examination of China’s current surveillance capabilities is needed to direct future investments in health information systems and to enable improved coordination between systems in support of ongoing control. Lessons drawn from China’s experience are applied to the current global movement to reduce the burden of helminthiases, where surveillance capacity based on improved diagnostics is urgently needed.

The geographical distribution and burden of trachoma in Africa

Background

There remains a lack of epidemiological data on the geographical distribution of trachoma to support global mapping and scale up of interventions for the elimination of trachoma. The Global Atlas of Trachoma (GAT) was launched in 2011 to address these needs and provide standardised, updated and accessible maps. This paper uses data included in the GAT to describe the geographical distribution and burden of trachoma in Africa.

Methods

Data assembly used structured searches of published and unpublished literature to identify cross-sectional epidemiological data on the burden of trachoma since 1980. Survey data were abstracted into a standardised database and mapped using geographical information systems (GIS) software. The characteristics of all surveys were summarized by country according to data source, time period, and survey methodology. Estimates of the current population at risk were calculated for each country and stratified by endemicity class.

Results

At the time of writing, 1342 records are included in the database representing surveys conducted between 1985 and 2012. These data were provided by direct contact with national control programmes and academic researchers (67%), peer-reviewed publications (17%) and unpublished reports or theses (16%). Prevalence data on active trachoma are available in 29 of the 33 countries in Africa classified as endemic for trachoma, and 1095 (20.6%) districts have representative data collected through population-based prevalence surveys. The highest prevalence of active trachoma and trichiasis remains in the Sahel area of West Africa and Savannah areas of East and Central Africa and an estimated 129.4 million people live in areas of Africa confirmed to be trachoma endemic.

Conclusion

The Global Atlas of Trachoma provides the most contemporary and comprehensive summary of the burden of trachoma within Africa. The GAT highlights where future mapping is required and provides an important planning tool for scale-up and surveillance of trachoma control.

In order to target resources and drugs to reach trachoma elimination targets by the year 2020, data on the burden of disease are required. Using prevalence data in African countries derived from the Global Atlas of Trachoma (GAT), the distribution of trachoma continues to be focused in East and West Sub-Saharan Africa, North Africa and a few endemic countries in Central Sub-Saharan Africa. Currently, 129.4 million people are estimated to live in areas that are confirmed to be trachoma endemic and 98 million are known to require access to the SAFE strategy. The maps and information presented in this work highlight the GAT as important open-access planning and advocacy tool for efforts to finalize trachoma mapping and assist national programmes in planning interventions.

Millennium development health metrics: where do Africa's children and women of childbearing age live?

The Millennium Development Goals (MDGs) have prompted an expansion in approaches to deriving health metrics to measure progress toward their achievement. Accurate measurements should take into account the high degrees of spatial heterogeneity in health risks across countries, and this has prompted the development of sophisticated cartographic techniques for mapping and modeling risks. Conversion of these risks to relevant population-based metrics requires equally detailed information on the spatial distribution and attributes of the denominator populations. However, spatial information on age and sex composition over large areas is lacking, prompting many influential studies that have rigorously accounted for health risk heterogeneities to overlook the substantial demographic variations that exist subnationally and merely apply national-level adjustments.

Here we outline the development of high resolution age- and sex-structured spatial population datasets for Africa in 2000-2015 built from over a million measurements from more than 20,000 subnational units, increasing input data detail from previous studies by over 400-fold. We analyze the large spatial variations seen within countries and across the continent for key MDG indicator groups, focusing on children under 5 and women of childbearing age, and find that substantial differences in health and development indicators can result through using only national level statistics, compared to accounting for subnational variation.

Progress toward meeting the MDGs will be measured through national-level indicators that mask substantial inequalities and heterogeneities across nations. Cartographic approaches are providing opportunities for quantitative assessments of these inequalities and the targeting of interventions, but demographic spatial datasets to support such efforts remain reliant on coarse and outdated input data for accurately locating risk groups. We have shown here that sufficient data exist to map the distribution of key vulnerable groups, and that doing so has substantial impacts on derived metrics through accounting for spatial demographic heterogeneities that exist within nations across Africa.

Mass treatment with azithromycin for trachoma: when is one round enough? Results from the PRET Trial in the Gambia

BACKGROUND

The World Health Organization has recommended three rounds of mass drug administration (MDA) with antibiotics in districts where the prevalence of follicular trachoma (TF) is ≥10% in children aged 1-9 years, with treatment coverage of at least 80%. For districts at 5-10% TF prevalence it was recommended that TF be assessed in 1-9 year olds in each community within the district, with three rounds of MDA provided to any community where TF≥10%. Worldwide, over 40 million people live in districts whose TF prevalence is estimated to be between 5 and 10%. The best way to treat these districts, and the optimum role of testing for infection in deciding whether to initiate or discontinue MDA, are unknown.

METHODS

In a community randomized trial with a factorial design, we randomly assigned 48 communities in four Gambian districts, in which the prevalence of trachoma was known or suspected to be above 10%, to receive annual mass treatment with expected coverage of 80-89% ("Standard"), or to receive an additional visit in an attempt to achieve coverage of 90% or more ("Enhanced"). The same 48 communities were randomised to receive mass treatment annually for three years ("3×"), or to have treatment discontinued if Chlamydia trachomatis (Ct) infection was not detected in a sample of children in the community after mass treatment (stopping rule("SR")). Primary outcomes were the prevalence of TF and of Ct infection in 0-5 year olds at 36 months.

RESULTS

The baseline prevalence of TF and of Ct infection in the target communities was 6.5% and 0.8% respectively. At 36 months the prevalence of TF was 2.8%, and that of Ct infection was 0.5%. No differences were found between the arms in TF or Ct infection prevalence either at baseline (Standard-3×: TF 5.6%, Ct 0.7%; Standard-SR: TF 6.1%, Ct 0.2%; Enhanced-3×: TF 7.4%, Ct 0.9%; and Enhanced-SR: TF 6.2%, Ct 1.2%); or at 36 months (Standard-3×: TF 2.3%, Ct 1.0%; Standard-SR TF 2.5%, Ct 0.2%; Enhanced-3× TF 3.0%, Ct 0.2%; and Enhanced-SR TF 3.2%, Ct 0.7% ). The implementation of the stopping rule led to treatment stopping after one round of MDA in all communities in both SR arms. Mean treatment coverage of children aged 0-9 in communities randomised to standard treatment was 87.7% at baseline and 84.8% and 88.8% at one and two years, respectively. Mean coverage of children in communities randomized to enhanced treatment was 90.0% at baseline and 94.2% and 93.8% at one and two years, respectively. There was no evidence of any difference in TF or Ct prevalence at 36 months resulting from enhanced coverage or from one round of MDA compared to three.

CONCLUSIONS

The Gambia is close to the elimination target for active trachoma. In districts prioritised for three MDA rounds, one round of MDA reduced active trachoma to low levels and Ct infection was not detectable in any community. There was no additional benefit to giving two further rounds of MDA. Programmes could save scarce resources by determining when to initiate or to discontinue MDA based on testing for Ct infection, and one round of MDA may be all that is necessary in some settings to reduce TF below the elimination threshold.

Will the SAFE strategy be sufficient to eliminate trachoma by 2020? Puzzlements and possible solutions

Since the inception of (the Global Elimination of Blinding Trachoma) GET 2020 in 1997 and the implementation of the SAFE strategy a year later, much progress has been made toward lowering the prevalence of trachoma worldwide with elimination of the disease in some countries. However, high recurrence of trichiasis after surgery, difficulty in controlling the reemergence of infection after mass distribution of azithromycin in some communities, the incomplete understanding of environment in relation to the disease, and the difficulty in establishing the prevalence of the disease in low endemic areas are some of the issues still facing completion of the GET 2020 goals. In this narrative review, literature was searched from 1998 to January 2013 in PubMed for original studies and reviews. Reasons for these ongoing problems are discussed, and several suggestions are made as avenues for exploration in relation to improving the SAFE strategy with emphasis on improving surgical quality and management of the mass treatment with antibiotics. In addition, more research needs to be done to better understand the approach to improve sanitation, hygiene, and environment. The main conclusion of this review is that scale-up is needed for all SAFE components, and more research should be generated from communities outside of Africa and Asia.

Toward an open-access global database for mapping, control, and surveillance of neglected tropical diseases

Background

After many years of general neglect, interest has grown and efforts came under way for the mapping, control, surveillance, and eventual elimination of neglected tropical diseases (NTDs). Disease risk estimates are a key feature to target control interventions, and serve as a benchmark for monitoring and evaluation. What is currently missing is a georeferenced global database for NTDs providing open-access to the available survey data that is constantly updated and can be utilized by researchers and disease control managers to support other relevant stakeholders. We describe the steps taken toward the development of such a database that can be employed for spatial disease risk modeling and control of NTDs.

Methodology

With an emphasis on schistosomiasis in Africa, we systematically searched the literature (peer-reviewed journals and ‘grey literature’), contacted Ministries of Health and research institutions in schistosomiasis-endemic countries for location-specific prevalence data and survey details (e.g., study population, year of survey and diagnostic techniques). The data were extracted, georeferenced, and stored in a MySQL database with a web interface allowing free database access and data management.

Principal Findings

At the beginning of 2011, our database contained more than 12,000 georeferenced schistosomiasis survey locations from 35 African countries available under http://www.gntd.org. Currently, the database is expanded to a global repository, including a host of other NTDs, e.g. soil-transmitted helminthiasis and leishmaniasis.

Conclusions

An open-access, spatially explicit NTD database offers unique opportunities for disease risk modeling, targeting control interventions, disease monitoring, and surveillance. Moreover, it allows for detailed geostatistical analyses of disease distribution in space and time. With an initial focus on schistosomiasis in Africa, we demonstrate the proof-of-concept that the establishment and running of a global NTD database is feasible and should be expanded without delay.

There is growing interest in the scientific community, health ministries, and other organizations to control and eventually eliminate neglected tropical diseases (NTDs). Control efforts require reliable maps of NTD distribution estimated from appropriate models and survey data on the number of infected people among those examined at a given location. This kind of data is often available in the literature as part of epidemiological studies. However, an open-access database compiling location-specific survey data does not yet exist. We address this problem through a systematic literature review, along with contacting ministries of health, and research institutions to obtain disease data, including details on diagnostic techniques, demographic characteristics of the surveyed individuals, and geographical coordinates. All data were entered into a database which is freely accessible via the Internet (http://www.gntd.org). In contrast to similar efforts of the Global Atlas of Helminth Infections (GAHI) project, the survey data are not only displayed in form of maps but all information can be browsed, based on different search criteria, and downloaded as Excel files for further analyses. At the beginning of 2011, the database included over 12,000 survey locations for schistosomiasis across Africa, and it is continuously updated to cover other NTDs globally.