Risk factors for trachoma in Mali

Beyond the SAFE strategy: Systematic review and meta-analysis of prevalence and associated factors of active trachoma among children in Ethiopia

BACKGROUND

Although the Surgery, Antibiotic, facial cleanliness, and environmental improvement (SAFE) strategy was adopted in Ethiopia over the last five years, there is still a high incidence of trachoma in areas with poor hygiene. In Ethiopia, a systematic review and meta-analysis were conducted before the implementation of SAFE implying, a need for the update. Therefore, this review gives the updated pooled prevalence and associated factors of active trachoma in Ethiopia after the implementation of SAFE.

METHOD

The literature search was performed from PubMed, Google Scholar, EMBASE, HINARI, Scopus, and Web of Sciences from January 1-30, 2024. Data were extracted by using a pre-tested and standardized data extraction format and analyzed using STATA 17 statistical software. I2 tests to appraise the heterogeneity across the included studies, a random-effect model to estimate the pooled prevalence, and a sub-group analysis to discern the viable source of heterogeneity were executed. Potential publication bias was also assessed by funnel plot, Egger's weighted correlation, and Begg's regression. The odds ratio with its 95% confidence was used to reckon the association between the prevalence and factors.

RESULT

From 504 identified studies, 20 articles were included. After the SAFE intervention, the national pooled prevalence of active trachoma among children was 21.16% (95% CI 17.28, 25.04). Fly-eye contact(Adjusted odds ratio (AOR) = 3.83, 95% CI: 2.25, 6.52), facial uncleanliness(AOR = 5.48, 95% CI: 3.02, 9.96), non-utilization of latrine (AOR = 3.30, 95% CI: 2.10, 5.18), and retrieving water from river(AOR = 2.94; 95%CI: 1.42, 6.05) were significantly associated with active trachoma.

CONCLUSION

In Ethiopia, the pooled prevalence of active trachoma after SAFE intervention was much higher than the World Health Organization (WHO) threshold prevalence. It continues to pose a significant public health concern and is far from the elimination of trachoma as a public health problem. Fly-eye contact, facial cleanliness, latrine utilization, and source of water increase the odds of active trachoma. Therefore, it is imperative to fine-tune the intervention focus on personal hygiene-related activities in removing dirt, fly-eye contact, and a well-structured approach for both constructing and ensuring the functionality of household taps and latrines. Additionally, It is crucial to initiate a reliable SAFE intervention in Ethiopia.

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

BACKGROUND

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

METHODS

Face photographs, conjunctival photographs, and conjunctival swabs were obtained on a random sample of 0-9-year-old children from each of 40 communities in Amhara region, Ethiopia. Face photographs were assessed for the presence of seven measures of an unclean face (i.e., wet nasal discharge, dry nasal discharge, wet ocular discharge, dry ocular discharge, food, dust/dirt, and flies) by three independent masked photo-graders. Conjunctival photographs were similarly graded in a masked fashion for signs of clinically active trachoma. Conjunctival swabs were processed for Chlamydia trachomatis DNA.

RESULTS

Of 2073 children with complete data, 808 (39%) had evidence of clinically active trachoma, 150 (7%) had evidence of ocular chlamydia infection, and 2524 (91%) had at least one measure of an unclean face. Dry ocular discharge had the strongest association with clinically active trachoma (age- and sex-adjusted prevalence ratio [PR] 1.4, 95% CI 1.2-1.6) and ocular chlamydia infection (PR 1.9, 95%CI 1.3-2.9), although significant associations were observed between each of the measures of facial uncleanliness and trachoma.

CONCLUSIONS

Masked assessment of face and conjunctival photographs confirmed prior observational studies that have noted associations between various measures of facial uncleanliness and trachoma. The causal relationship between facial uncleanliness and trachoma is unclear since many features used to measure facial cleanliness (e.g., ocular discharge, nasal discharge, and flies) could be consequences of antecedent ocular chlamydia infection.

TRIAL REGISTRATION

NCT02754583, clinicaltrials.gov.

Water, Sanitation, and Hygiene (WASH) Factors Influencing the Effectiveness of Mass Drug Administration to Eliminate Trachoma as a Public Health Problem in Malawi

PURPOSE

Following a national population-based trachoma survey in Malawi one round of azithromycin mass drug administration (MDA) was carried out, with a post-MDA impact survey showing TF prevalence below 5% and considered eliminated as a public health problem. However, active trachoma was still present in over 200 children. We assessed whether water, sanitation, and hygiene (WASH) factors were associated with ongoing presence of TF in children aged 1-9 years following MDA.

METHODS

A secondary analysis was performed on a sub-set of the post-MDA impact survey data for children aged 1-9 years. We used a logistic regression analysis, adjusted for clustering at the household and village level.

RESULTS

Among 16,142 children aged 1-9 years, 209 (1.3%) had TF after MDA. Factors associated with a significantly lower odds of TF after MDA were living in a household with a handwashing facility (aOR: 0.37) and living in a household where water for washing is located further away from the home (30 min away aOR: 0.39, p = .034, or more than 1 h away aOR: 0.31, p = .018) compared with water in the yard.

CONCLUSION

The inverse association between a domestic handwashing facility and TF is consistent with previous findings, but the association of increasing distance to collect water for washing with a reduced risk of TF was unexpected and may reflect the impact of drought and unmeasured behavioural factors related to water usage. A more comprehensive collection of sociodemographic and WASH factor information in population-based trachoma surveys will provide insight into achieving and maintaining low levels of trachoma.

Time trends and heterogeneity in the disease burden of trachoma, 1990-2019: a global analysis

PURPOSE

To evaluate the epidemiological trends and associated risk factors of disease burden due to trachoma.

METHODS

Data for the country-specific disability-adjusted life year (DALY) number, rate and age-standardised rate of trachoma together with related data of other common eye diseases were acquired from the Global Burden of Disease Study 2019 database. The Socio-Demographic Index (SDI), Human Development Index (HDI), inequality-adjusted HDI and other related indices were obtained from published data or publicly available databases. Regression analyses were conducted to evaluate the associations between potential risk factors and the age-standardised DALY burden of trachoma.

RESULTS

The global DALY burden due to trachoma decreased by 37% from 1990 to 2019 and decreased by 69.8% after adjusting for age and population growth, and, in available 1990-2019 data, had the greatest reduction in attributable DALYs of all common eye disease, with the others analysed being cataract, glaucoma, refractive disorders and age-related macular degeneration. Women had higher age-standardised DALY burden due to trachoma than men (p<0.001). The African region (p<0.001) had the heaviest burden among global regions. The age-standardised DALY rate was higher in countries with lower income (p<0.001) and lower SDI (p<0.001). Higher disease burden due to trachoma was associated with lower HDI (β=-48.102, 95% CI -86.888 to -9.316, p=0.016), lower SDI (β=-48.063, 95% CI -83.702 to -12.423, p<0.001) and lower expected years of schooling (β=-2.352, 95% CI -3.756 to -0.948, p=0.002).

CONCLUSIONS

The global disease burden due to trachoma decreased from 1990 to 2019 and it had the greatest reduction compared with other common eye diseases. Lower HDI, socioeconomic status and educational level were related to a higher national disease burden of trachoma. Our findings could provide necessary information for trachoma control and prevention.

Trachoma

Trachoma is a neglected tropical disease caused by infection with conjunctival strains of Chlamydia trachomatis. It can result in blindness. Pathophysiologically, trachoma is a disease complex composed of two linked chronic processes: a recurrent, generally subclinical infectious-inflammatory disease that mostly affects children, and a non-communicable, cicatricial and, owing to trichiasis, eventually blinding disease that supervenes in some individuals later in life. At least 150 infection episodes over an individual's lifetime are needed to precipitate trichiasis; thus, opportunity exists for a just global health system to intervene to prevent trachomatous blindness. Trachoma is found at highest prevalence in the poorest communities of low-income countries, particularly in sub-Saharan Africa; in June 2021, 1.8 million people worldwide were going blind from the disease. Blindness attributable to trachoma can appear in communities many years after conjunctival C. trachomatis transmission has waned or ceased; therefore, the two linked disease processes require distinct clinical and public health responses. Surgery is offered to individuals with trichiasis and antibiotic mass drug administration and interventions to stimulate facial cleanliness and environmental improvement are designed to reduce infection prevalence and transmission. Together, these interventions comprise the SAFE strategy, which is achieving considerable success. Although much work remains, a continuing public health problem from trachoma in the year 2030 will be difficult for the world to excuse.

Community-level trachoma ecological associations and the use of geospatial analysis methods: A systematic review

Background

Trachoma is targeted for global elimination as a public health problem by 2030. Understanding individual, household, or community-associated factors that may lead to continued transmission or risk of recrudescence in areas where elimination has previously been achieved, is essential in reaching and maintaining trachoma elimination. We aimed to identify climatic, demographic, environmental, infrastructural, and socioeconomic factors associated in the literature with trachoma at community-level and assess the strength of their association with trachoma. Because of the potential power of geospatial analysis to delineate the variables most strongly associated with differences in trachoma prevalence, we then looked in detail at geospatial analysis methods used in previous trachoma studies.

Methods

We conducted a systematic literature review using five databases: Medline, Embase, Global Health, Dissertations & Theses Global, and Web of Science, including publications from January 1950 to January 2021. The review protocol was prospectively registered with PROSPERO (CRD42020191718).

Results

Of 35 eligible studies, 29 included 59 different trachoma-associated factors, with eight studies also including spatial analysis methods. Six studies included spatial analysis methods only. Higher trachomatous inflammation—follicular (TF) prevalence was associated with areas that: had lower mean annual precipitation, lower mean annual temperatures, and lower altitudes; were rural, were less accessible, had fewer medical services, had fewer schools; and had lower access to water and sanitation. Higher trachomatous trichiasis (TT) prevalence was associated with higher aridity index and increased distance to stable nightlights. Of the 14 studies that included spatial methods, 11 used exploratory spatial data analysis methods, three used interpolation methods, and seven used spatial modelling methods.

Conclusion

Researchers and decision-makers should consider the inclusion and potential influence of trachoma-associated factors as part of both research activities and programmatic priorities. The use of geospatial methods in trachoma studies remains limited but offers the potential to define disease hotspots and areas of potential recrudescence to inform local, national, and global programmatic needs.

The ambitious target to eliminate trachoma as a public health problem has led to impressive strides in reducing the disease burden worldwide, with the implementation of the World Health Organization (WHO)-endorsed surgery, antibiotics, facial cleanliness and environmental improvement (SAFE) strategy. However, some areas have struggled to reach the elimination threshold after the prescribed number of antibiotic mass drug administration rounds, and some areas have had evidence of trachoma recrudescence after previously having reached the elimination threshold. This systematic review assessed climatic, demographic, environmental, infrastructural, and socioeconomic factors associated with trachoma to reveal which covariates are associated with ongoing or renewed trachoma transmission. We also explored how geospatial analysis, which could help identify areas with ongoing trachoma transmission or heightened risk of recrudescence, has been used in previous trachoma studies. Thirty-five studies met the inclusion criteria for the review. Results indicated that researchers and decision-makers should consider the inclusion and potential influence of precipitation, temperature, and altitude along with variables related to ruralness, accessibility, access to medical services and schools, and community-level water and sanitation coverage, as part of both research activities and programmatic priorities for trachoma elimination.

Predicting future community-level ocular Chlamydia trachomatis infection prevalence using serological, clinical, molecular, and geospatial data

Trachoma is an infectious disease characterized by repeated exposures to Chlamydia trachomatis (Ct) that may ultimately lead to blindness. Efficient identification of communities with high infection burden could help target more intensive control efforts. We hypothesized that IgG seroprevalence in combination with geospatial layers, machine learning, and model-based geostatistics would be able to accurately predict future community-level ocular Ct infections detected by PCR. We used measurements from 40 communities in the hyperendemic Amhara region of Ethiopia to assess this hypothesis. Median Ct infection prevalence among children 0-5 years old increased from 6% at enrollment, in the context of recent mass drug administration (MDA), to 29% by month 36, following three years without MDA. At baseline, correlation between seroprevalence and Ct infection was stronger among children 0-5 years old (ρ = 0.77) than children 6-9 years old (ρ = 0.48), and stronger than the correlation between active trachoma and Ct infection (0-5y ρ = 0.56; 6-9y ρ = 0.40). Seroprevalence was the strongest concurrent predictor of infection prevalence at month 36 among children 0-5 years old (cross-validated R2 = 0.75, 95% CI: 0.58-0.85), though predictive performance declined substantially with increasing temporal lag between predictor and outcome measurements. Geospatial variables, a spatial Gaussian process, and stacked ensemble machine learning did not meaningfully improve predictions. Serological markers among children 0-5 years old may be an objective tool for identifying communities with high levels of ocular Ct infections, but accurate, future prediction in the context of changing transmission remains an open challenge.

Active trachoma prevalence and its associated factors among children aged 1-9 years in rural residents of Lare District, Southwest Ethiopia

AIM

To determine the prevalence of active trachoma and its associated factors among children in Lare District, Southwest Ethiopia, 2019.

METHODS

A community-based cross-sectional study was conducted. A total of 620 participants were recruited using a multi-stage sampling technique. A structured questionnaire, torch, and magnifying loupes were used for data collection. The data was entered into epidemiological information and exported to statistical package for social science version 20 for analysis. The bi-variable and multivariable Logistic regression analysis model was fitted to identify factors associated with active trachoma. Odds ratio with a 95%CI was used to show the direction and strength of association between independent and outcome variables.

RESULTS

A total of 610 children participated in this study with a response rate of 98.39%. The prevalence of active trachoma was 132 (21.60%; 95%CI: 18.40-24.70). Family size being 6-9 (AOR=2.34; 95%CI: 1.14-5.02), presence of more than two preschool children in a house (AOR=2.04; 95%CI: 1.12-3.70), open field waste disposal system (AOR=2.62; 95%CI: 1.00-6.80) and type of latrine being uncovered (AOR=4.12; 95%CI: 2.00-8.51) were positively associated with active trachoma. On the other side, water consumption being 40-60 liters per day was a protective factor for active trachoma.

CONCLUSION

The prevalence of active trachoma is high among children aged 1-9y in Lare District. Uncovered latrine, open field waste disposal system, family sizes of 6-9, and the presence of more than two preschool children in a house are associated with the occurrence of active trachoma. On the other side, water consumption of 40-60 liters is a protective factor.

Community-based health financing: empirical evaluation of the socio-demographic factors determining its uptake in Awka, Anambra state, Nigeria

BACKGROUND

There is an increasing global concern of financing poor people who live in low- and middle-income countries. The burden of non-communicable diseases of these people is, by in large, connected to a lack of access to effective and affordable medical care, weak financing, and delivery of health services. Policymakers have assumed, until recently, that poor people in developing countries would not pay health insurance premiums for the cost of future hospitalization. The emergence of community-based health financing (CBHF) has brought forth a renewed and empowered alternative. CBHF schemes are designed to be sustainable, varying in size, and well organized. Developing countries, such as Nigeria, have been testing and finetuning such schemes in the hope that they may 1 day reciprocate high-income countries.

METHODS

A sample size of 372 respondents was used to assess the slums of Awka, the capital city of Anambra State, Nigeria, and empirically evaluate the socio-demographic characteristics of those who uptake CBHF using the provider Jamii Bora Trust (JBT). Cross-sectional research used a quantitative research approach with the instrumentality of structured questionnaires. Descriptive analysis was adopted to determine the socio-demographic characteristics of those who have CBHF uptake in Awka and evaluate the presence and benefits of CBHF in the city's slums.

RESULTS

The results show that more youth and middle-aged persons from 18 to 50 years are more insured (i.e., 73.8% combined) than those who are over 50 years of age. Gender distribution confirm more females (i.e., 61.9%) to be health-insured than their male counterpart (i.e., 38.1%). This perhaps reflected the reproductive roles by women and the fact that women have better health-seeking behavioral attitude. Moreover, the results correlate with previous studies that confirm women are more involved in local sustainable associations in low-income settings, of this nature, in sub-Saharan Africa. Corroborating this further, married people are more insured (i.e., 73.8%) than those who are not married (i.e., 26.2%) and insured members report higher use of hospitalization care than the non-insured.

CONCLUSION

CBHF uptake favored members in the lower income quintiles who are more likely to use healthcare services covered by the JBT scheme. This confirmed that prepayment schemes and the pooling of risk could reduce financial barriers to healthcare among the urban poor. Recommendations are suggested to improve enrollment levels in the CBHF programs.

The impact of access to water supply and sanitation on the prevalence of active trachoma in Ethiopia: A systematic review and meta-analysis

Background

Trachoma is a worldwide infectious disease causing blindness. Trachoma continued as a public health problem in Ethiopia due to a lack of sanitation and inadequate prevention strategies. This study aimed to identify the impact of water supply and sanitation intervention on preventing active trachoma among children.

Methods

Systematic literature searches were performed from 4 international databases. The search involved articles published from January 1995 up to March 2019. The Cochran Q and I² statistical tests were used to check heterogeneity among the studies. A random-effect meta-analysis was employed to determine the pooled estimates with a 95% confidence interval (CI). Data analysis was performed using the CMA V.3 and RevMan 5 software program, and the result of the systematic review was reported using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Findings

Out of 211 studies screened for the analysis, only 29 studies were finally included in this systematic review and meta-analysis. The result revealed factors that are significantly associated with increased odds of active trachoma. Accordingly, households with no access to toilet facilities (odds ratio [OR]: 2.04, 95% CI: 1.75–2.38), no access to improved water (OR: 1.58, 95% CI: 1.27–1.96), and do not practice regular face washing for children (OR: 4.19, 95% CI: 3.02–5.81) have shown increased odds of active trachoma. Besides, the results show a higher prevalence of active trachoma among children who did not wash their faces with soap and frequently.

Conclusions

The study found strong evidence that lack of access to water, sanitation, and hygiene (WASH) was associated with increased prevalence of active trachoma among children. Therefore, a comprehensive and partnership-oriented program is needed to tackle the problem, but further study will be required to strengthen its implementation.

Empowering Maasai women behind the camera: Photovoice as a tool for trachoma control

BACKGROUND

Photovoice is a method used to help engage community members to understand local realities and promote social change. Photovoice uses cameras in the hands of participants as a tool to visually document a specified topic. Photos taken by participants allow for reflection and stimulate dialog on an issue to ideally lead to social change. Trachoma, hyperendemic in Maasai communities in Northern Tanzania, is the commonest infectious cause of blindness worldwide, caused by chlamydia trachomatis. The bacterial infection commonly occurs in childhood and over many years repeated infections leads to inflammation and scarring of the eyelid. Often as adults this leads to the upper eyelid turning inward and eyelashes scratching the eye, resulting in pain and eventually blindness. We used photovoice as a tool for Maasai women to share their lived experiences of educating peers on trachoma and ultimately empowering women in this society.

METHODS

This public engagement intervention was conducted September thru October 2017. We held a workshop on trachoma control for 20 Maasai women including use of photovoice method. Women were asked to disseminate information from the trachoma control workshop to their community and to capture their experiences using disposable cameras. Five weeks post-workshop we facilitated a discussion and women displayed photos of the successes and challenges they encountered as advocates for trachoma control in their community.

INTERVENTION OUTCOMES

It was observed throughout the process and at the photo discussion meeting, that women articulated empowerment by this experience; as educators, agents of change and a source of valued information.

CONCLUSION

Photovoice should be considered for future interventions as a communication tool on health issues and to empower women to be ambassadors for health promotion.

Children as messengers of health knowledge? Impact of health promotion and water infrastructure in schools on facial cleanliness and trachoma in the community

BACKGROUND

Health promotion is essential to the SAFE strategy for trachoma elimination. Schools are a valuable venue for health promotion. However, there is little literature about the impact of health education and water infrastructure in schools on facial cleanliness and trachoma in the community. Our study aimed to describe the current state of school health promotion in Kongwa, Tanzania, and to examine the transferability of health messages from schools to the community at large.

METHODOLOGY/FINDINGS

A cross-sectional survey was carried out in all 92 villages in Kongwa district, which included 85 primary schools. Data were collected on health messages and water infrastructure in the schools. A random sample of 3084 children aged 0-5 were examined for facial cleanliness in all villages. In 50 villages, a random sample of 50 children aged 1-9 per village were examined for follicular trachoma (TF). Thirty-seven (44.6%) schools had educational materials on face-washing. Fifty (60.2%) schools had a washing station. The presence of a health teacher was correlated with having posters on face washing in classrooms. The presence of face-washing materials was correlated with the availability of washing stations. Neither teachers mentioning face-washing in health curricula nor educational materials in classrooms were associated with clean faces or trachoma in the community. Having a washing station in the school was associated with lower community rates of trachoma.

CONCLUSIONS

Primary school health messages and materials on trachoma were not associated with clean faces or lower rates of trachoma in the community. The target audience for primary school health promotion is likely the students themselves, without immediate rippling effects in the community. A long-term perspective should be considered during the implementation of health promotion in schools. The goal of school health promotion should be training the next generation of parents and community health leaders in combatting trachoma.

Prevalence and risk factors of active trachoma among primary school children of Amhara Region, Northwest Ethiopia

Purpose:

Trachoma is the leading infectious cause of blindness in the world. It is caused by conjunctival infection with the bacterium Chlamydia trachomatis. The objective of this study was to determine the prevalence and risk factors of active trachoma among primary school children in Amhara region, Ethiopia.

Methods:

A cross-sectional study was conducted from April to May 2018. Data on sociodemographic and health characteristics of a child were collected using a structured questionnaire and eye examination for this study. Bivariate and multiple logistic regression statistical analyses were used to determine the prevalence and risk factors of active trachoma among primary school children living in Amhara region, Northwest Ethiopia.

Results:

The prevalence of active trachoma among primary school children living in Amhara region was 10.3% in this study. The results of multiple logistic regression analysis revealed that children who wash their face at least two times per day (AOR = 0.37, 95% CI: 0.14–0.97), children with no flies on their face (AOR = 0.12, 95% CI: 0.10–0.30) had significantly lower risk of being infected by trachoma and children of households who spend 30 min to 1 h to fetch water (AOR = 10.02, 95% CI: 1.10–93.53) had significantly higher risk of being infected by trachoma in the study area.

Conclusion:

The result of this study showed that risk factors: frequency of face washing per day, presence of flies on child's face during interview, and time required to fetch water for the household were found to be significantly associated with trachoma. Therefore, the study recommends that any concerned bodies directed at prevention and control of trachoma among primary school children living in Amhara region should give special attention to these factors. Implementing the World Health Organization (WHO) endorsed SAFE (Surgery, Antibiotics, Facial cleanliness, Environmental improvement) strategy was recommended for the effective prevention and control of trachoma in the study area since the prevalence of active trachoma, 10.3% was higher than the WHO recommended thresholds (>10% prevalence).

Association of environmental risk factors and trachoma in Gashoho Health District, Burundi

Background

Burundi is currently not meeting targets for elimination of trachoma and trichiasis by 2020 (GET2020). The recommended SAFE strategy (Surgery, antibiotics, face washing and environmental improvement) is currently not fully implemented in many areas of Burundi. The existence of associations between face-washing, sanitation and trachoma prevalence remain undocumented.

Methods

A convenience sample of 468 individuals from 117 households was drawn from attendees at trachoma clinics set up in four villages. Trachoma status, sex and age were recorded for all household members. Adult household members were surveyed about access to clean water and toilets, and knowledge of trachoma risk factors. Associations between cases of active trachoma per household and environmental risk factors were evaluated using generalised estimating equations.

Results

The overall prevalence of active trachoma was 7.1% (95% CI 5.0–9.6%), but 19.5% (95% CI13.7–26.4%) in children under nine years old. 0.9% (95% CI 0.3–2.0) of participants had trichiasis. Access to a sanitary toilet more than halved the odds of active trachoma (OR 0.43, 95% CI 0.25–0.74%), however, participants did not appreciate this association.

Conclusion

Access to sanitation was associated with the occurrence of active trachoma. Future research should focus on whether improving knowledge of and access to sanitation might reduce trachoma prevalence.

Perceptions and practices of community members relating to trachoma in Africa: a qualitative systematic review protocol

OBJECTIVE

The objective of this systematic review is to synthesize and present the best available evidence on community perceptions and practices relating to trachoma in Africa.

INTRODUCTION

Globally, trachoma is the leading cause of blindness and is responsible for about 1.4% of all cases of blindness. The African continent is the worst affected, with about 1.9 million cases of trichiasis (61%). While interventions are currently being implemented to combat the disease in Africa, very little is known by decision makers about community perceptions and practices relating to trachoma, which may hinder successful implementation.

INCLUSION CRITERIA

Studies with participants, regardless of their health status, gender, religion and ethnicity, aged 14 and over conducted in any African country, will be considered. Studies on Africans, conducted out of the continent and those involving healthcare professionals, will not be included in this review.

METHODS

Qualitative studies, published in English from 1996 onwards. will be considered. Databases to be searched will include, but not be limited to: PubMed, CINAHL, Embase and PsycINFO. Study selection, critical appraisal and data extraction will be conducted by two independent reviewers, using the appropriate JBI methodology and any disagreement will be resolved by discussion or with a third reviewer. Qualitative findings will be synthesized using the appropriate JBI methodology, following the meta-aggregation approach. Where textual pooling is not possible, the findings will be presented in narrative form. The ConQual approach will be used to grade synthesized findings, and these will be presented in a Summary of Findings.

Community-level Association between Clinical Trachoma and Ocular Chlamydia Infection after MASS Azithromycin Distribution in a Mesoendemic Region of Niger

Purpose: The clinical sign trachomatous inflammation - follicular (TF) is used to monitor indication for and response to mass azithromycin distribution in trachoma-endemic communities. Here, we assess the relationship between TF, trachomatous inflammation - intense (TI), and infection with ocular Chlamydia trachomatis over time during annual mass azithromycin distribution. Methods: We used data from a cluster-randomized trial of mass azithromycin distribution for trachoma control in a mesoendemic region of Niger. This study includes 24 communities that received 3 years of annual mass azithromycin distribution. TF, TI, and ocular chlamydia infection were monitored among children aged 0-5 years. We assessed the correlation between the prevalence of ocular chlamydia infection and 1) TF and 2) TI prevalence over time. Results: At baseline, ocular chlamydia prevalence was 21.2% (95% CI 14.3-28.1%), TF prevalence was 27.7% (95% CI 21.2-34.2%), and TI prevalence was 8.3% (95% CI 5.2-11.5%). The prevalence of all three measures decreased significantly over time (P < 0.001). At baseline, ocular chlamydia infection prevalence was strongly correlated with both TF (rho = 0.78, P < 0.0001) and TI (rho = 0.76, P < 0.0001). The correlation between ocular chlamydia infection and both TF and TI was weak at months 12 and 24. At 36 months, when TF prevalence had dropped below 10%, ocular chlamydia infection and TF were moderately correlated (rho = 0.70, P= 0.0002). Conclusions: Both TF and TI are good indicators of infection prevalence prior to mass azithromycin distribution. However, this relationship may be affected by repeated rounds of mass azithromycin distribution.

Knowledge, perceptions and experiences of trachoma among Maasai in Tanzania: Implications for prevention and control

BACKGROUND

The Alliance for the Global Elimination of Trachoma has set the target for eliminating trachoma as a public health problem by 2020. However, challenges remain, including socio-cultural issues. Districts in Northern Tanzania, predominantly inhabited by the Maasai ethnic group, remain endemic for trachoma. We explored socio-cultural factors that may impact the elimination of trachoma.

METHODS/FINDINGS

This study was nested within a larger ethnographic study of trachoma among Maasai in Northern Tanzania. We used stratified random sampling and semi-structured interviews to examine knowledge and understanding. Interviews were conducted and recorded in Maa, by a native Maa speaking trained interviewer. Transcripts were translated into English. A framework method for a content analysis was used. There was awareness of trachoma and basic symptoms. Yet understanding of etiology and prevention was poor. Trachoma was attributed to pollen, dust, and smoke. Water was recognized as beneficial, but seen as treatment and not prevention. Traditional medicines were most often used for treating conjunctival inflammation, with the most common being a rough leaf used to scratch the inside of the eyelid until it bleeds. Knowledge of mass drug administration (MDA) was inconsistent, although many thought it helped the community, but it was perceived as only for children and the sick. Many participants reported not taking azithromycin and some had no recollection of MDA six months earlier. There was little connection between childhood infection, trichiasis and related blindness. Trichiasis was often seen as a problem of old women, and treated locally by epilation.

CONCLUSION/SIGNIFICANCE

Understanding indigenous knowledge may help guide control programs, tailor them to local contexts, address local beliefs and dispel misunderstandings. There is an essential need to understand the social, cultural and political context of the target community to deliver effective programs. Despite limited knowledge, the community recognized trachoma as a public health problem. Results have implications for disease control programs in other marginalized communities.

Understanding the spatial distribution of trichiasis and its association with trachomatous inflammation-follicular

BACKGROUND

Whilst previous work has identified clustering of the active trachoma sign "trachomatous inflammation-follicular" (TF), there is limited understanding of the spatial structure of trachomatous trichiasis (TT), the rarer, end-stage, blinding form of disease. Here we use community-level TF prevalence, information on access to water and sanitation, and large-scale environmental and socio-economic indicators to model the spatial variation in community-level TT prevalence in Benin, Cote d'Ivoire, DRC, Guinea, Ethiopia, Malawi, Mozambique, Nigeria, Sudan and Uganda.

METHODS

We fit binomial mixed models, with community-level random effects, separately for each country. In countries where spatial correlation was detected through a semi-variogram diagnostic check we then fitted a geostatistical model to the TT prevalence data including TF prevalence as an explanatory variable.

RESULTS

The estimated regression relationship between community-level TF and TT was significant in eight countries. We estimate that a 10% increase in community-level TF prevalence leads to an increase in the odds for TT ranging from 20 to 86% when accounting for additional covariates.

CONCLUSION

We find evidence of an association between TF and TT in some parts of Africa. However, our results also suggest the presence of additional, country-specific, spatial risk factors which modulate the variation in TT risk.

Prevalence of Trachoma in Senegal: Results of Baseline Surveys in 17 Districts

Purpose: Senegal is endemic for trachoma, an infectious and potentially blinding eye disease. To complete the country’s district-level baseline map of trachoma, we conducted population-based surveys in 17 health districts that were suspected-endemic but had yet to be surveyed.

Methods: We randomly selected 30 clusters (villages) per district and 30 households per village, and estimated the district-level prevalences of trachomatous inflammation—follicular (TF) in children aged 1–9 years, and trichiasis in persons aged ≥15 years. Data on household-level water, sanitation, and hygiene variables were also collected. Global Trachoma Mapping Project methods were followed in training, fieldwork, and data handling.

Results: 25,704 children aged 1–9 years and 30,345 adults aged 15 years and above were examined. In children aged 1–9 years, the prevalence of TF was <5% in all 17 districts, with the exception of Saint-Louis (5.1%, 95% CI 3.2–7.5). Trichiasis prevalence in participants aged 15 years and above ranged by district from 0%–1.1% (95% CI 0.7–1.5), with 9 districts having trichiasis prevalences above the elimination threshold of 0.2%. Trichiasis was seen to be significantly less frequent in males than in females (0.17% [95% CI 0.12–0.24] versus 0.49% [95% CI 0.38–0.61], p < 0.001). The prevalence of trichiasis rose steeply with age; 62% of cases were observed in people aged 55 years or above.

Conclusions: Active trachoma is not a public health problem in 16 of the 17 surveyed districts, and implementation of the full Surgery (S) – Antibiotics (A) – Facial cleanliness (F) – Environmental improvement (E) strategy is not a programmatic priority. Increased provision of trichiasis surgery is warranted in nine districts.

Comparison of Mass Azithromycin Coverage Targets of Children in Niger: A Cluster-Randomized Trachoma Trial

Repeated oral azithromycin distribution targeted only to children has proven effective in reducing the ocular Chlamydia that causes trachoma. Here, we assess whether an enhanced coverage target of at least 90% of children is superior to the World Health Organization recommendation of at least 80%. Twenty-four trachoma-endemic communities in Matamèye, Niger, were randomized to a single day of azithromycin distribution aiming for at least 80% coverage or up to 4 days of treatment and > 90% coverage of children under age 12. All distributions were biannual. Children < 5 years of age and adults > 15 years were monitored for ocular Chlamydia infection by polymerase chain reaction every 6 months for 36 months in children and at baseline and 36 months in adults. Ocular Chlamydia prevalence in children decreased from 24.9% (95% confidence interval [CI] 15.9-33.8%) to 4.4% (95% CI 0.6-8.2%, P < 0.001) at 36 months in the standard coverage arm and from 15.6% (95% CI 10.0-21.2%) to 3.3% (95% CI 1.0-5.5%; P < 0.001) in the enhanced coverage arm. Enhanced coverage reduced ocular Chlamydia prevalence in children more quickly over time compared with standard (P = 0.04). There was no difference between arms at 36 months in children (2.4% lower with enhanced coverage, 95% CI 7.7-12.5%; P = 0.60). No infection was detected in adults at 36 months. Increasing antibiotic coverage among children from 80% to 90% may yield only short term improvements for trachoma control programs. Targeting treatment to children alone may be sufficient for trachoma control in this setting.

Environmental risk factors and the associated morbidity in a periurban area, Alexandria, Egypt

BACKGROUND

According to the WHO, nearly 24% of the global disease burden is attributable to environmental risk factors (RFs). People living in periurban areas are particularly at risk due to lack of basic sanitation requirements.

OBJECTIVE

To investigate the possible association between environmental RFs and disease prevalence for a community living in a periurban area in Alexandria, Egypt.

MATERIALS AND METHODS

A cross-sectional study was conducted in 2012. The study sample consisted of 355 families. An interviewing questionnaire and an observation checklist were used for data collection. In addition, 10 drinking water samples were randomly collected for physical, chemical, and bacteriological analyses. The questionnaire included questions on indoor environmental RFs as well as morbidity in the study sample, and the observation checklist covered outdoor environmental RFs. The environmental risk was determined using a risk score whose calculation was based upon the presence/absence of 10 indoor and 12 outdoor environmental RFs. The association between risk scores and 14 morbidities was investigated using unconditional logistic regression analysis, expressed as odds ratio (OR) and 95% confidence interval (CI).

RESULTS

A significant association was found between the total environmental risk score and respiratory diseases (OR=2.298, 95% CI: 1.231-4.291), diarrhea (OR=2.083, 95% CI: 1.102-3.939), liver diseases (OR=2.491, 95% CI: 1.067-5.819), skin diseases (OR=1.821, 95% CI: 1.012-3.310), and bronchial asthma (OR=2.228, 95% CI: 1.066-4.565). Noncommunicable diseases such as cardiovascular diseases and musculoskeletal diseases did not show any significant association with environmental RFs.

CONCLUSION AND RECOMMENDATIONS

Environmental RFs have an adverse impact on health within communities living in periurban areas. It is recommended that sanitation be improved and various outdoor environmental RFs be addressed in these underprivileged areas, as well as health education campaigns be organized aiming at raising the awareness of residents on indoor environmental RFs and ways to prevent them.

Prevalence of Trachoma in Benishangul Gumuz Region, Ethiopia: Results of Seven Population-Based Surveys from the Global Trachoma Mapping Project

Purpose: Trachoma is a major cause of blindness in Ethiopia, and targeted for elimination as a public health problem by the year 2020. Prevalence data are needed to plan interventions. We set out to estimate the prevalence of trachoma in each evaluation unit of grouped districts (“woredas”) in Benishangul Gumuz region, Ethiopia.

Methods: We conducted seven cross-sectional community-based surveys, covering 20 woredas, between December 2013 and January 2014, as part of the Global Trachoma Mapping Project (GTMP). The standardized GTMP training package and methodologies were used.

Results: A total of 5828 households and 21,919 individuals were enumerated in the surveys. 19,583 people (89.3%) were present when survey teams visited. A total of 19,530 (99.7%) consented to examination, 11,063 (56.6%) of whom were female. The region-wide age- and sex-adjusted trichiasis prevalence in adults aged ≥15 years was 1.3%. Two evaluation units covering four woredas (Pawe, Mandura, Bulen and Dibate) with a combined rural population of 166,959 require implementation of the A, F and E components of the SAFE strategy (surgery, antibiotics, facial cleanliness and environmental improvement) for at least three years before re-survey, and intervention planning should begin for these woredas as soon as possible.

Conclusion: Both active trachoma and trichiasis are public health problems in Benishangul Gumuz, which needs implementation of the full SAFE strategy.

Prevalence of and Risk Factors for Trachoma in Oromia Regional State of Ethiopia: Results of 79 Population-Based Prevalence Surveys Conducted with the Global Trachoma Mapping Project

PURPOSE

To complete the baseline trachoma map in Oromia, Ethiopia, by determining prevalences of trichiasis and trachomatous inflammation - follicular (TF) at evaluation unit (EU) level, covering all districts (woredas) without current prevalence data or active control programs, and to identify factors associated with disease.

METHODS

Using standardized methodologies and training developed for the Global Trachoma Mapping Project, we conducted cross-sectional community-based surveys from December 2012 to July 2014.

RESULTS

Teams visited 46,244 households in 2037 clusters from 252 woredas (79 EUs). A total of 127,357 individuals were examined. The overall age- and sex-adjusted prevalence of trichiasis in adults was 0.82% (95% confidence interval, CI, 0.70-0.94%), with 72 EUs covering 240 woredas having trichiasis prevalences above the elimination threshold of 0.2% in those aged ≥15 years. The overall age-adjusted TF prevalence in 1-9-year-olds was 23.4%, with 56 EUs covering 218 woredas shown to need implementation of the A, F and E components of the SAFE strategy (surgery, antibiotics, facial cleanliness and environmental improvement) for 3 years before impact surveys. Younger age, female sex, increased time to the main source of water for face-washing, household use of open defecation, low mean precipitation, low mean annual temperature, and lower altitude, were independently associated with TF in children. The 232 woredas in 64 EUs in which TF prevalence was ≥5% require implementation of the F and E components of the SAFE strategy.

CONCLUSION

Both active trachoma and trichiasis are highly prevalent in much of Oromia, constituting a significant public health problem for the region.

'If an Eye Is Washed Properly, It Means It Would See Clearly': A Mixed Methods Study of Face Washing Knowledge, Attitudes, and Behaviors in Rural Ethiopia

BACKGROUND

Face cleanliness is a core component of the SAFE (Surgery, Antibiotics, Facial cleanliness, and Environmental improvements) strategy for trachoma control. Understanding knowledge, attitudes, and behaviors related to face washing may be helpful for designing effective interventions for improving facial cleanliness.

METHODS

In April 2014, a mixed methods study including focus groups and a quantitative cross-sectional study was conducted in the East Gojjam zone of the Amhara region of Ethiopia. Participants were asked about face washing practices, motivations for face washing, use of soap (which may reduce bacterial load), and fly control strategies.

RESULTS

Overall, both knowledge and reported practice of face washing was high. Participants reported they knew that washing their own face and their children's faces daily was important for hygiene and infection control. Although participants reported high knowledge of the importance of soap for face washing, quantitative data revealed strong variations by community in the use of soap for face washing, ranging from 4.4% to 82.2% of households reporting using soap for face washing. Cost and forgetfulness were cited as barriers to the use of soap for face washing. Keeping flies from landing on children was a commonly cited motivator for regular face washing, as was trachoma prevention.

CONCLUSIONS

Interventions aiming to improve facial cleanliness for trachoma prevention should focus on habit formation (to address forgetfulness) and address barriers to the use of soap, such as reducing cost. Interventions that focus solely on improving knowledge may not be effective for changing face-washing behaviors.

Prevalence and factors associated with trachoma among children aged 1-9 years in Zala district, Gamo Gofa Zone, Southern Ethiopia

BACKGROUND

Trachoma is the leading cause of preventable blindness worldwide. It is common in areas where people are socioeconomically deprived. Globally, approximately 1.2 billion people live in trachoma-endemic areas, in which, 40.6 million individuals have active trachoma and 8.2 million have trichiasis. According to the World Health Organization's 2007 report, globally close to 1.3 million people are blind due to trachoma, while approximately 84 million suffer from active trachoma. The National Survey (2007) of Ethiopia showed a prevalence of 40.1% active trachoma among children aged 1-9 years. Trachoma is still endemic in most parts of Ethiopia.

OBJECTIVE

To assess prevalence of trachoma and factors associated with it among children aged 1-9 years in Zala district, Gamo Gofa Zone, Southern Nations, Nationalities, and Peoples' Region.

METHODS

A community-based cross-sectional study was conducted in Zala district from February 28 to March 26, 2014. A total of 611 children were examined for trachoma based on the simplified World Health Organization 1983 classification. A multistage stratified sampling technique with a systematic random sampling technique was used to select study participants. Data were collected by using a semistructured pretested questionnaire and clinical eye examination. The data were entered using EpiData version 3.1 and analyzed using SPSS version 16. Multivariable logistic regression analysis was used to identify independently associated factors.

RESULTS

The overall prevalence of active trachoma cases was 224 (36.7%) consisting of 207 (92.4%) trachomatous follicles, eight (3.6%) trachomatous intense, and nine (4.0%) combination of trachomatous follicle and trachomatous intense. Inadequate knowledge of family head about trachoma (adjusted odds ratio [AOR] =2.8 [95% CI: 1.9, 4.2]); ≤10 m latrine distance (AOR =1.6 [95% confidence interval {CI}: 1.09, 2.4]); presence of above two preschool children (AOR =2.2 [95% CI: 1.3, 3.7]), flies on the face (AOR =6.3 [95% CI: 2.7, 14.7]), and unclean face (AOR =2.4 [95% CI: 1.5, 3.9]) were found to be independently associated with trachoma.

CONCLUSION

Trachoma among children in Zala district is a disease of public health importance. Factors like inadequate knowledge about trachoma by the head of the family, ≤10 m latrine distance, presence of above two preschool children, flies on the face, and an unclean face were independently associated with trachoma among children. So strengthening of antibiotic use, face washing, and environmental improvement strategy implementation is mandatory.

Knowledge, practices and perceptions of trachoma and its control among communities of Narok County, Kenya

Background

Trachoma is the leading infectious cause of blindness in the world. It is commonly found in cultural groups with poor hygiene. Trachoma control includes Surgery, Antibiotics, Facial cleanliness and Environmental Improvement (SAFE). Potentially blinding and active trachoma are monitored using trachomatous trichiasis (TT) in adults and trachoma inflammation-follicular (TF) in children aged 1–9 years respectively. A cross-sectional study to assess the knowledge, practices and perceptions of trachoma and its control was conducted in the endemic communities in Narok County.

Methods

Qualitative methods were used for data collection. Using purposive sampling, 12 focus group discussions (FGDs) with single sex adult and young men and women groups of homogenous characteristics, 12 key informant interviews with opinion leaders and 5 in-depth interviews (IDIs) with trichiasis patients and 6 with persons who have undergone trichiasis surgery were conducted. Data was audio recorded, transcribed, coded and analyzed manually by study themes; knowledge, practices and perceptions of trachoma transmission, infection signs, prevention and control.

Results

Majority of the community members had knowledge of trachoma and its transmission. The practices that contributed to transmission of infection included: failure to wash faces and bathe regularly, sharing of water basins and towels for face washing, traditional methods of trachoma treatment and dirty household environment. Due to socio-cultural perceptions, toilets were unacceptable and use of bushes for human waste disposal was common. Poor perceptions on disease susceptibility, flies on children’s faces, latrine ownership and usage and separation of human and animal dwellings also played a role in the transmission of trachoma. Fear of loss of sight during surgery was a deterrent to its uptake and a desire to be able to see and take care of domestic animals promoted surgery uptake. Majority of the community members were appreciative of Mass Drug Administration (MDA) though side effect such as vomiting and diarrhoea were reported.

Conclusion

Poor practices and related socio-cultural perceptions are important risk factors in sustaining trachoma infection and transmission. Community members require health education for behavior change and awareness creation about surgery, MDA and its potential side effects for elimination of trachoma in Narok County, Kenya.

Trial registration

KEMRI SSC 2785. Registered 2 September 2014.

Prevalence of Trachoma in Car-Nicobar Island, India after Three Annual Rounds of Mass Drug Administration with Azithromycin

Background

A high proportion of active trachoma infection in children of Car-Nicobar Island was reported through the Trachoma Rapid Assessment survey conducted in year 2010 by the same researchers. Annual mass drug treatment with azithromycin was administered from years 2010–12 to all individuals residing in this island for reducing the burden of active trachoma infection. A cross-sectional prevalence survey was conducted in the year 2013 to assess the post-treatment burden of trachoma in this population.

Methods

In the 15 randomly selected compact segments from each village of the island, children aged 1–9 years were examined for evidence of active trachoma infection and participants aged ten years and above were examined for trachomatous trichiasis and corneal opacity.

Results

A total of 809 children (1–9 years) and 2735 adults were examined. Coverage with azithromycin for all the three rounds was more than 80%. The prevalence of active trachoma infection in children aged 1–9 years old was 6.8% (95% CI 5.1, 8.5) and Trachomatous Trichiasis (TT) was 3.9% (95% CI 3.2, 4.6). The risk factors associated with active trachoma infection were older age and unclean faces. The risk factors associated with TT were older age and lower literacy level.

Conclusion

Trachoma has not been eliminated from Car-Nicobar Island in accordance to ‘Global Elimination of Trachoma, 2020’ guidelines. Sustained efforts and continuous surveillance admixed with adequate programmatic response is imperative for elimination of trachoma in the island.

On-plot drinking water supplies and health: A systematic review

Many studies have found that household access to water supplies near or within the household plot can reduce the probability of diarrhea, trachoma, and other water-related diseases, and it is generally accepted that on-plot water supplies produce health benefits for households. However, the body of research literature has not been analyzed to weigh the evidence supporting this. A systematic review was conducted to investigate the impacts of on-plot water supplies on diarrhea, trachoma, child growth, and water-related diseases, to further examine the relationship between household health and distance to water source and to assess whether on-plot water supplies generate health gains for households. Studies provide evidence that households with on-plot water supplies experience fewer diarrheal and helminth infections and greater child height. Findings suggest that water-washed (hygiene associated) diseases are more strongly impacted by on-plot water access than waterborne diseases. Few studies analyzed the effects of on-plot water access on quantity of domestic water used, hygiene behavior, and use of multiple water sources, and the lack of evidence for these relationships reveals an important gap in current literature. The review findings indicate that on-plot water access is a useful health indicator and benchmark for the progressive realization of the Sustainable Development Goal target of universal safe water access as well as the human right to safe water.

Trachoma in remote Indigenous Australia: a review and public health perspective

OBJECTIVES

Trachoma remains a major health concern in many remote Indigenous Australian communities, despite behaviour-modifying and biomedical strategies. This review aims to examine the social epidemiology of trachoma in remote Indigenous communities and identify practical, sustainable strategies to alter the social determinants of the disease.

METHODS

A systematic search and critical review explored the proximal, intermediate and distal determinants of trachoma. The impact of swimming pools in remote Indigenous communities on trachoma and other infectious diseases was further examined.

RESULTS

Having a clean face was found to be protective for trachoma, but face-washing education programs have produced no significant benefits. Sanitation infrastructure in a community was the key determinant of facial cleanliness. Installation of swimming pools in remote Indigenous communities has been demonstrated to reduce the prevalence of several common childhood infections. However, minimal research has explored the impact of pools on trachoma rates.

CONCLUSIONS

The locally supported construction of pools in remote Indigenous communities may contribute to a decline in trachoma. A prospective, controlled trial is needed to test this hypothesis in endemic communities.

IMPLICATIONS

If validated by a well-designed study, pool construction may provide a much sought-after practical government strategy to combat trachoma in remote Indigenous communities.

Multilevel Analysis of Trachomatous Trichiasis and Corneal Opacity in Nigeria: The Role of Environmental and Climatic Risk Factors on the Distribution of Disease

The distribution of trachoma in Nigeria is spatially heterogeneous, with large-scale trends observed across the country and more local variation within areas. Relative contributions of individual and cluster-level risk factors to the geographic distribution of disease remain largely unknown. The primary aim of this analysis is to assess the relationship between climatic factors and trachomatous trichiasis (TT) and/or corneal opacity (CO) due to trachoma in Nigeria, while accounting for the effects of individual risk factors and spatial correlation. In addition, we explore the relative importance of variation in the risk of trichiasis and/or corneal opacity (TT/CO) at different levels. Data from the 2007 National Blindness and Visual Impairment Survey were used for this analysis, which included a nationally representative sample of adults aged 40 years and above. Complete data were available from 304 clusters selected using a multi-stage stratified cluster-random sampling strategy. All participants (13,543 individuals) were interviewed and examined by an ophthalmologist for the presence or absence of TT and CO. In addition to field-collected data, remotely sensed climatic data were extracted for each cluster and used to fit Bayesian hierarchical logistic models to disease outcome. The risk of TT/CO was associated with factors at both the individual and cluster levels, with approximately 14% of the total variation attributed to the cluster level. Beyond established individual risk factors (age, gender and occupation), there was strong evidence that environmental/climatic factors at the cluster-level (lower precipitation, higher land surface temperature, higher mean annual temperature and rural classification) were also associated with a greater risk of TT/CO. This study establishes the importance of large-scale risk factors in the geographical distribution of TT/CO in Nigeria, supporting anecdotal evidence that environmental conditions are associated with increased risk in this context and highlighting their potential use in improving estimates of disease burden at large scales.

Trichiasis (TT) and corneal opacity (CO) are chronic stages of trachoma, which remains an important cause of blindness. This study used multilevel spatial models to investigate risk factors for TT/CO in Nigeria, including data for more than 13,500 adults aged 40 years and above collected in the 2007 National Blindness and Visual Impairment survey. Individual-level risk factors were consistent with those identified in other studies, including a higher risk in females, older individuals and those with lower socioeconomic status. After controlling for these factors, there was evidence that a number of environmental and climatic factors are associated with the distribution of TT/CO in Nigeria. These findings establish for the Nigerian context the importance of risk factors at different scales for the later stages of trachoma, supporting anecdotal evidence that hotter, drier environmental conditions are associated with increased risk.

Trachoma

Trachoma is the most common infectious cause of blindness. Repeated episodes of infection with Chlamydia trachomatis in childhood lead to severe conjunctival inflammation, scarring, and potentially blinding inturned eyelashes (trichiasis or entropion) in later life. Trachoma occurs in resource-poor areas with inadequate hygiene, where children with unclean faces share infected ocular secretions. Much has been learnt about the epidemiology and pathophysiology of trachoma. Integrated control programmes are implementing the SAFE Strategy: surgery for trichiasis, mass distribution of antibiotics, promotion of facial cleanliness, and environmental improvement. This strategy has successfully eliminated trachoma in several countries and global efforts are underway to eliminate blinding trachoma worldwide by 2020.

Risk factors for active trachoma and ocular Chlamydia trachomatis infection in treatment-naïve trachoma-hyperendemic communities of the Bijagós Archipelago, Guinea Bissau

BACKGROUND

Trachoma, caused by ocular infection with Chlamydia trachomatis, is hyperendemic on the Bijagós Archipelago of Guinea Bissau. An understanding of the risk factors associated with active trachoma and infection on these remote and isolated islands, which are atypical of trachoma-endemic environments described elsewhere, is crucial to the implementation of trachoma elimination strategies.

METHODOLOGY/PRINCIPAL FINDINGS

A cross-sectional population-based trachoma prevalence survey was conducted on four islands. We conducted a questionnaire-based risk factor survey, examined participants for trachoma using the World Health Organization (WHO) simplified grading system and collected conjunctival swab samples for 1507 participants from 293 randomly selected households. DNA extracted from conjunctival swabs was tested using the Roche Amplicor CT/NG PCR assay. The prevalence of active (follicular and/or inflammatory) trachoma was 11% (167/1508) overall and 22% (136/618) in 1-9 year olds. The prevalence of C. trachomatis infection was 18% overall and 25% in 1-9 year olds. There were strong independent associations of active trachoma with ocular and nasal discharge, C. trachomatis infection, young age, male gender and type of household water source. C. trachomatis infection was independently associated with young age, ocular discharge, type of household water source and the presence of flies around a latrine.

CONCLUSIONS/SIGNIFICANCE

In this remote island environment, household-level risk factors relating to fly populations, hygiene behaviours and water usage are likely to be important in the transmission of ocular C. trachomatis infection and the prevalence of active trachoma. This may be important in the implementation of environmental measures in trachoma control.

Effect of water, sanitation, and hygiene on the prevention of trachoma: a systematic review and meta-analysis

BACKGROUND

Trachoma is the world's leading cause of infectious blindness. The World Health Organization (WHO) has endorsed the SAFE strategy in order to eliminate blindness due to trachoma by 2020 through "surgery," "antibiotics," "facial cleanliness," and "environmental improvement." While the S and A components have been widely implemented, evidence and specific targets are lacking for the F and E components, of which water, sanitation, and hygiene (WASH) are critical elements. Data on the impact of WASH on trachoma are needed to support policy and program recommendations. Our objective was to systematically review the literature and conduct meta-analyses where possible to report the effects of WASH conditions on trachoma and identify research gaps.

METHODS AND FINDINGS

We systematically searched PubMed, Embase, ISI Web of Knowledge, MedCarib, Lilacs, REPIDISCA, DESASTRES, and African Index Medicus databases through October 27, 2013 with no restrictions on language or year of publication. Studies were eligible for inclusion if they reported a measure of the effect of WASH on trachoma, either active disease indicated by observed signs of trachomatous inflammation or Chlamydia trachomatis infection diagnosed using PCR. We identified 86 studies that reported a measure of the effect of WASH on trachoma. To evaluate study quality, we developed a set of criteria derived from the GRADE methodology. Publication bias was assessed using funnel plots. If three or more studies reported measures of effect for a comparable WASH exposure and trachoma outcome, we conducted a random-effects meta-analysis. We conducted 15 meta-analyses for specific exposure-outcome pairs. Access to sanitation was associated with lower trachoma as measured by the presence of trachomatous inflammation-follicular or trachomatous inflammation-intense (TF/TI) (odds ratio [OR] 0.85, 95% CI 0.75-0.95) and C. trachomatis infection (OR 0.67, 95% CI 0.55-0.78). Having a clean face was significantly associated with reduced odds of TF/TI (OR 0.42, 95% CI 0.32-0.52), as were facial cleanliness indicators lack of ocular discharge (OR 0.42, 95% CI 0.23-0.61) and lack of nasal discharge (OR 0.62, 95% CI 0.52-0.72). Facial cleanliness indicators were also associated with reduced odds of C. trachomatis infection: lack of ocular discharge (OR 0.40, 95% CI 0.31-0.49) and lack of nasal discharge (OR 0.56, 95% CI 0.37-0.76). Other hygiene factors found to be significantly associated with reduced TF/TI included face washing at least once daily (OR 0.76, 95% CI 0.57-0.96), face washing at least twice daily (OR 0.85, 95% CI 0.80-0.90), soap use (OR 0.76, 95% CI 0.59-0.93), towel use (OR 0.65, 95% CI 0.53-0.78), and daily bathing practices (OR 0.76, 95% CI 0.53-0.99). Living within 1 km of a water source was not found to be significantly associated with TF/TI or C. trachomatis infection, and the use of sanitation facilities was not found to be significantly associated with TF/TI.

CONCLUSIONS

We found strong evidence to support F and E components of the SAFE strategy. Though limitations included moderate to high heterogenity, low study quality, and the lack of standard definitions, these findings support the importance of WASH in trachoma elimination strategies and the need for the development of standardized approaches to measuring WASH in trachoma control programs.

Trachoma elimination in remote Indigenous Northern Territory communities: baseline health-promotion study

Identify trachoma knowledge, attitudes and practice of staff in clinics, schools and community workplace settings to optimise trachoma-elimination health-promotion programs in the Katherine West Health Board region of the Northern Territory. Prior to the introduction of a suite of health promotion resources the Indigenous Eye Health Unit and Katherine West Health Board conducted a baseline survey of open, multi-choice and closed questions regarding knowledge, attitudes and practices in relation to trachoma with 72 staff members over a 6-month period in 2010-11. Data were analysed for differences between settings. Two significant barriers and one enabling factor were identified. One in five staff members in clinics and 29% of staff members in schools were unaware they lived and worked in a trachoma-endemic area. One-third of school staff and 38% of clinic staff considered it normal for children to have dirty faces. However, the majority of participants felt comfortable talking about hygiene issues with others. The presence of dirty faces in young Indigenous children underpins the continuing prevalence of trachoma. Increasing the awareness of the health effects of children's nasal and ocular secretions and changing community acceptance of dirty faces as the norm will reduce the risk of trachoma and other childhood infections. Staff in clinics, schools and community work settings can play a role in trachoma elimination by actively encouraging clean faces whenever they are dirty and by including face washing in holistic hygiene and health education. Staff in schools may need additional support. Trachoma-elimination health promotion should increase awareness of trachoma prevalence and encourage all who work and live in remote Indigenous communities to take action to promote facial cleanliness and good hygiene practices.

The impact of climatic risk factors on the prevalence, distribution, and severity of acute and chronic trachoma

BACKGROUND AND OBJECTIVES

Trachoma is the most common cause of infectious blindness. Hot, dry climates, dust and water scarcity are thought to be associated with the distribution of trachoma but the evidence is unclear. The aim of this study was to evaluate the epidemiological evidence regarding the extent to which climatic factors explain the current prevalence, distribution, and severity of acute and chronic trachoma. Understanding the present relationship between climate and trachoma could help inform current and future disease elimination.

METHODS

A systematic review of peer-reviewed literature was conducted to identify observational studies which quantified an association between climate factors and acute or chronic trachoma and which met the inclusion and exclusion criteria. Studies that assessed the association between climate types and trachoma prevalence were also reviewed.

RESULTS

Only eight of the 1751 papers retrieved met the inclusion criteria, all undertaken in Africa. Several papers reported an association between trachoma prevalence and altitude in highly endemic areas, providing some evidence of a role for temperature in the transmission of acute disease. A robust mapping study found strong evidence of an association between low rainfall and active trachoma. There is also consistent but weak evidence that the prevalence of trachoma is higher in savannah-type ecological zones. There were no studies on the effect of climate in low endemic areas, nor on the effect of dust on trachoma.

CONCLUSION

Current evidence on the potential role of climate on trachoma distribution is limited, despite a wealth of anecdotal evidence. Temperature and rainfall appear to play a role in the transmission of acute trachoma, possibly mediated through reduced activity of flies at lower temperatures. Further research is needed on climate and other environmental and behavioural factors, particularly in arid and savannah areas. Many studies did not adequately control for socioeconomic or environmental confounders.

Follicular trachoma and trichiasis prevalence in an urban community in The Gambia, West Africa: is there a need to include urban areas in national trachoma surveillance?

OBJECTIVES

Urban areas are traditionally excluded from trachoma surveillance activities, but due to rapid expansion and population growth, the urban area of Brikama in The Gambia may be developing social problems that are known risk factors for trachoma. It is also a destination for many migrants who may be introducing active trachoma into the area. This study aimed to determine the prevalence and risk factors for follicular trachoma and trichiasis in Brikama.

METHODS

A community-based cross-sectional prevalence survey including 27 randomly selected households in 12 randomly selected enumeration areas (EAs) of Brikama. Selected households were offered eye examinations, and the severity of trachoma was graded according to WHO's simplified grading system. Risk factor data were collected from each household via a questionnaire.

RESULTS

The overall prevalence of trachomatous inflammation-follicular (TF) in children aged 1-9 years was 3.8% (95% CI 2.5-5.6), and the overall prevalence of trichiasis in adults aged ≥15 years was 0.46% (95% CI 0.17-1.14). EA prevalence of TF varied from 0% to 8.4%. The major risk factors for TF were dirty faces (P < 0.01, OR = 9.23, 95% CI 1.97-43.23), nasal discharge (P = 0.039, OR = 5.11, 95% CI 1.08-24.10) and residency in Brikama for <1 year (P = 0.047, OR = 7.78, 95% CI 1.03-59.03).

CONCLUSIONS

Follicular trachoma can be considered to have been eliminated as a public health problem in Brikama according to WHO criteria. However, as the prevalence in some EAs is >5%, it may be prudent to include Brikama in surveillance programmes. Trichiasis remains a public health problem (>0.1%), and active case finding needs to be undertaken.

The easiest children to reach are most likely to be infected with ocular Chlamydia trachomatis in trachoma endemic areas of Niger

BACKGROUND

Control programs for trachoma use mass antibiotic distributions to treat ocular Chlamydia trachomatis in an effort to eliminate this disease worldwide. To determine whether children infected with ocular Chlamydia are more likely to present later for examination than those who are uninfected, we compare the order of presentation for examination of children 0-5 years, and the presence of ocular Chlamydia by PCR in 4 villages in Niger where trachoma is endemic.

METHODS

We conducted a cluster-randomized, controlled trial where 48 randomly selected villages in Niger are divided into 4 study arms of different mass treatment strategies. In a substudy of the main trial, we randomly selected 1 village from each of the 4 study arms (4 total villages) and we evaluated the odds of ocular Chlamydia versus the rank order of presentation for examination and laboratory assessment before treatment was offered.

FINDINGS

We found the odds of harboring ocular Chlamydia dropped by more than 70% from the first child examined to the last child examined (OR 0.27, 95% CI 0.13-0.59, P = 0.001) in the 4 randomly selected villages. We found the odds of active trachoma dropped by 80% from the first child examined to the last child examined (OR 0.20, 95% CI 0.10-0.4, P<0.0001) in the 48 villages in the main trial.

INTERPRETATION

This study demonstrates that even if the WHO recommended 80% treatment coverage is not reached in certain settings, children 0-5 years with the greatest probability of ocular Chlamydia have higher odds of receiving attention because they are the first to present. These results suggest there may be diminishing returns when using scarce resources to track down the last few children in a mass treatment program.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00792922.

Association between water related factors and active trachoma in Hai district, Northern Tanzania

BACKGROUND

Trachoma is widely distributed in sub-Saharan Africa and is mainly associated with poor water accessibility. However, these associations have never been demonstrated in some of the communities, especially in northern Tanzania. To cover that gap, the present case control study was conducted to assess the association of water related factors, general hygiene and active trachoma among preschool and school age children in Hai district, northern Tanzania.

RESULTS

Families reported to use > 60 litres of water per day were less likely to have active disease (OR= 0.4, 95% CI: 0.1 - 0.3; P<0.001) compared to households collecting ≤ 60 litres. The risk of having trachoma increased with increase in distance to the water point (OR= 6.5, 95% CI; 1.8 - 16.7; P= 0.003). Households members who reported to use < 2 liters of water for face washing were more likely to be trachomatous (OR= 5.12, 95% CI: 1.87-14.6, P = 0.001). Increased number of preschool children in the household was also associated with increased risk of active trachoma by 2.46 folds.

CONCLUSIONS

Improving water supply near the households and providing public health education focusing on improving households socio-economic status and individual hygiene especially in pre-school children in part will help to reduce the prevalence of the disease. In addition, integrating public health education with other interventions such as medical interventions remains important.

Risk of trachoma in a SAFE intervention area

To determine prevalence and risk factors of trachoma in communities receiving intervention with the SAFE strategy (surgery, antibiotic, face washing, environmental hygiene), a cross-sectional trachoma survey was undertaken in 2006 in the Enemor district of southern Ethiopia where the SAFE program has been implemented for over five years. A sample of 374 household heads and 2,080 individuals were interviewed and examined for trachoma using an established trachoma grading system of the World Health Organization. The most prominent risk factors were identified with logistic regression analysis. Among individuals >14 years of age, the prevalence of trichiasis was 9.04 % [confidence interval (CI) 7.4-10.6]. People >40 years of age [odds ratio (OR) 1.7; CI 1.2-2.7), women (OR 2.2; CI 1.1-4.3), and illiterates (OR 3; CI 1.4-6.8) had increased risk of trichiasis. Coverage of surgical and antibiotic services was 46 and 85.5 %, respectively. Prevalence of active follicular trachoma (TF) in children aged 1-9 years was 33.1 % (CI 29.4-37.1). Unclean faces (OR 5.9; CI 4.3-8.3) and not being in school (OR 2.1; CI 1.3-3.3) were significantly associated with TF. Clean faces were observed in 56.1 % of children and improved with age and schooling (P < 0.001, Chi-squared test). Household latrine use (74.4 %) was associated with knowledge about SAFE and economic level (P ≤ 0.004, Chi-squared tests). Elderly illiterate women remain at risk of becoming blind from trachoma even in intervention areas. Trachoma particularly affects children without clean faces or opportunity for schooling. Provision of SAFE services with high coverage should be sustained in trachoma-hyperendemic areas.

Community risk factors for ocular Chlamydia infection in Niger: pre-treatment results from a cluster-randomized trachoma trial

BACKGROUND

Trachoma control programs utilize mass azithromycin distributions to treat ocular Chlamydia trachomatis as part of an effort to eliminate this disease world-wide. But it remains unclear what the community-level risk factors are for infection.

METHODS

This cluster-randomized, controlled trial entered 48 randomly selected communities in a 2×2 factorial design evaluating the effect of different treatment frequencies and treatment coverage levels. A pretreatment census and examination established the prevalence of risk factors for clinical trachoma and ocular chlamydia infection including years of education of household head, distance to primary water source, presence of household latrine, and facial cleanliness (ocular discharge, nasal discharge, and presence of facial flies). Univariate and multivariate associations were tested using linear regression and Bayes model averaging.

FINDINGS

There were a total of 24,536 participants (4,484 children aged 0-5 years) in 6,235 households in the study. Before treatment in May to July 2010, the community-level prevalence of active trachoma (TF or TI utilizing the World Health Organization [WHO] grading system) was 26.0% (95% CI: 21.9% to 30.0%) and the mean community-level prevalence of chlamydia infection by Amplicor PCR was 20.7% (95% CI: 16.5% to 24.9%) in children aged 0-5 years. Univariate analysis showed that nasal discharge (0.29, 95% CI: 0.04 to 0.54; P = 0.03), presence of flies on the face (0.40, 95% CI: 0.17 to 0.64; P = 0.001), and years of formal education completed by the head of household (0.07, 95% CI: 0.07 to 0.13; P = 0.03) were independent risk factors for chlamydia infection. In multivariate analysis, facial flies (0.26, 95% CI: 0.02 to 0.49; P = 0.03) and years of formal education completed by the head of household (0.06, 95% CI: 0.008 to 0.11; P = 0.02) were associated risk factors for ocular chlamydial infection.

INTERPRETATION

We have found that the presence of facial flies and years of education of the head of the household are risk factors for chlamydia infection when the analysis is done at the community level.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00792922.

Risk factors for ocular chlamydia after three mass azithromycin distributions

Background

An important component of the World Health Organization's comprehensive trachoma elimination strategy is the provision of repeated annual mass azithromycin distributions, which are directed at reducing the burden of ocular chlamydia. Knowledge of characteristics associated with infection after mass antibiotic treatments could allow trachoma programs to focus resources to those most likely to be infected with ocular chlamydia.

Methodology/Principal Findings

We monitored 12 communities in rural Ethiopia that had received 3 annual mass azithromycin treatments as part of a cluster-randomized trial for trachoma. One year after the third treatment, a random sample of children from each village received conjunctival examination for follicular trachomatous inflammation (TF) and intense trachomatous inflammation (TI), conjunctival swabbing for chlamydial RNA and DNA, and a household survey. The primary outcome for this study was RNA evidence of ocular chlamydia, which we detected in 41 of 573 swabbed children (7.2%, 95%CI 2.7–17.8). In multivariate mixed effects logistic regression models, ocular chlamydial RNA was significantly associated with ocular discharge (OR 2.82, 95%CI 1.07–7.42), missing the most recent mass azithromycin treatment (OR 2.49, 95%CI 1.02–6.05), having a sibling with ocular chlamydia (OR 4.44, 95%CI 1.60–12.29), and above-median community population (OR 7.81, 95%CI 1.56–39.09). Ocular chlamydial infection was also independently associated with TF (OR 3.42, 95%CI 1.56–7.49) and TI (OR 5.39, 95%CI 2.43–11.98).

Conclusions/Significance

In areas with highly prevalent trachoma treated with multiple rounds of mass azithromycin, trachoma programs could consider continuing mass azithromycin treatments in households that have missed prior mass antibiotic treatments, in households with clinically active trachoma, and in larger communities.

Trachoma, which is the leading infectious cause of blindness worldwide, is caused by repeated ocular infection with Chlamydia trachomatis. Treatment for trachoma includes mass azithromycin treatments to the entire community. The World Health Organization recommends at least 3 rounds of annual mass antibiotic distributions in areas with trachoma, with further mass treatments based on the prevalence of trachoma. However, there are other options for communities that have received several rounds of treatment. For example, programs could continue antibiotic treatments only in those households most likely to have infected individuals. In this study, we performed trachoma monitoring on children from 12 Ethiopian communities one year after a third mass azithromycin treatment, and conducted a household survey at the same time. We found that children were more likely to be infected with ocular chlamydia if they had ocular inflammatory signs or ocular discharge, or if they had missed the preceding antibiotic treatment, had an infected sibling, or came from a larger community. These risk factors suggest that after mass azithromycin treatments, trachoma programs could consider continuing antibiotic distributions to households that have missed prior antibiotic distributions, in households with children who have the clinical signs of trachoma, and in larger communities.

Hygiene: new hopes, new horizons

Although promotion of safe hygiene is the single most cost-effective means of preventing infectious disease, investment in hygiene is low both in the health and in the water and sanitation sectors. Evidence shows the benefit of improved hygiene, especially for improved handwashing and safe stool disposal. A growing understanding of what drives hygiene behaviour and creative partnerships are providing fresh approaches to change behaviour. However, some important gaps in our knowledge exist. For example, almost no trials of the effectiveness of interventions to improve food hygiene in developing countries are available. We also need to figure out how best to make safe hygiene practices matters of daily routine that are sustained by social norms on a mass scale. Full and active involvement of the health sector in getting safe hygiene to all homes, schools, and institutions will bring major gains to public health.

Trachoma prevalence and associated risk factors in the gambia and Tanzania: baseline results of a cluster randomised controlled trial

Background

Blinding trachoma, caused by ocular infection with Chlamydia trachomatis, is targeted for global elimination by 2020. Knowledge of risk factors can help target control interventions.

Methodology/Principal Findings

As part of a cluster randomised controlled trial, we assessed the baseline prevalence of, and risk factors for, active trachoma and ocular C. trachomatis infection in randomly selected children aged 0–5 years from 48 Gambian and 36 Tanzanian communities. Both children's eyes were examined according to the World Health Organization (WHO) simplified grading system, and an ocular swab was taken from each child's right eye and processed by Amplicor polymerase chain reaction to test for the presence of C. trachomatis DNA. Prevalence of active trachoma was 6.7% (335/5033) in The Gambia and 32.3% (1008/3122) in Tanzania. The countries' corresponding Amplicor positive prevalences were 0.8% and 21.9%. After adjustment, risk factors for follicular trachoma (TF) in both countries were ocular or nasal discharge, a low level of household head education, and being aged ≥1 year. Additional risk factors in Tanzania were flies on the child's face, being Amplicor positive, and crowding (the number of children per household). The risk factors for being Amplicor positive in Tanzania were similar to those for TF, with the exclusion of flies and crowding. In The Gambia, only ocular discharge was associated with being Amplicor positive.

Conclusions/Significance

These results indicate that although the prevalence of active trachoma and Amplicor positives were very different between the two countries, the risk factors for active trachoma were similar but those for being Amplicor positive were different. The lack of an association between being Amplicor positive and TF in The Gambia highlights the poor correlation between the presence of trachoma clinical signs and evidence of C. trachomatis infection in this setting. Only ocular discharge was associated with evidence of C. trachomatis DNA in The Gambia, suggesting that at this low endemicity, this may be the most important risk factor.

Trial Registration

ClinicalTrials.gov NCT00792922

Trachoma is caused by Chlamydia trachomatis and is the leading infectious cause of blindness. The World Health Organization's (WHO) control strategy includes antibiotic treatment of all community members, facial cleanliness, and environmental improvements. By determining how prevalent trachoma is, decisions can be made whether control activities need to be put in place. Knowing what factors make people more at risk of having trachoma can help target trachoma control efforts to those most at risk. We looked at the prevalence of active trachoma and C. trachomatis infection in the eyes of children aged 0–5 years in The Gambia and Tanzania. We also measured risk factors associated with having active trachoma or infection. The prevalence of both active trachoma and infection was lower in The Gambia (6.7% and 0.8%, respectively) than in Tanzania (32.3% and 21.9%, respectively). Risk factors for active trachoma were similar in the two countries. For infection, the risk factors in Tanzania were similar to those for TF, whereas in The Gambia, only ocular discharge was associated with infection. These results show that although the prevalence of active trachoma and infection is very different between the two countries, the risk factors for active trachoma are similar but those for infection are different.

Targeting trachoma control through risk mapping: the example of Southern Sudan

BACKGROUND

Trachoma is a major cause of blindness in Southern Sudan. Its distribution has only been partially established and many communities in need of intervention have therefore not been identified or targeted. The present study aimed to develop a tool to improve targeting of survey and control activities.

METHODS/PRINCIPAL FINDINGS

A national trachoma risk map was developed using Bayesian geostatistics models, incorporating trachoma prevalence data from 112 geo-referenced communities surveyed between 2001 and 2009. Logistic regression models were developed using active trachoma (trachomatous inflammation follicular and/or trachomatous inflammation intense) in 6345 children aged 1-9 years as the outcome, and incorporating fixed effects for age, long-term average rainfall (interpolated from weather station data) and land cover (i.e. vegetation type, derived from satellite remote sensing), as well as geostatistical random effects describing spatial clustering of trachoma. The model predicted the west of the country to be at no or low trachoma risk. Trachoma clusters in the central, northern and eastern areas had a radius of 8 km after accounting for the fixed effects.

CONCLUSION

In Southern Sudan, large-scale spatial variation in the risk of active trachoma infection is associated with aridity. Spatial prediction has identified likely high-risk areas to be prioritized for more data collection, potentially to be followed by intervention.

Epidemiology and control of trachoma: systematic review

Trachoma is the commonest infectious cause of blindness. Recurrent episodes of infection with serovars A-C of Chlamydia trachomatis cause conjunctival inflammation in children who go on to develop scarring and blindness as adults. It was estimated that in 2002 at least 1.3 million people were blind from trachoma, and currently 40 million people are thought to have active disease and 8.2 million to have trichiasis. The disease is largely found in poor, rural communities in developing countries, particularly in sub-Saharan Africa. The WHO promotes trachoma control through a multifaceted approach involving surgery, mass antibiotic distribution, encouraging facial cleanliness and environmental improvements. This has been associated with significant reductions in the prevalence of active disease over the past 20 years, but there remain a large number of people with trichiasis who are at risk of blindness.