Trachoma, flies and environmental factors in Burkina Faso

Twenty-Three Population-Based Trachoma Prevalence Surveys in the Central and Northern Regions of Benin, 2018-2022

PURPOSE

Trachoma is an infectious eye disease caused by Chlamydia trachomatis. Infection causes conjunctival inflammation, which can be manifested by the sign known as trachomatous inflammation-follicular (TF). Repeated inflammation leads to eyelid scarring, which in susceptible individuals can cause in-turning of the eyelashes, referred to as trachomatous trichiasis (TT). This article describes 23 population-based surveys conducted in northern and central Benin to determine TF and/or TT prevalence for trachoma elimination purposes.

METHODS

A total of 18 surveys estimated the prevalence of both TF and TT: two baseline surveys, eight impact surveys after implementation of interventions against trachoma, and eight surveillance surveys. Five other evaluation units (EUs) were surveyed for TT only. To estimate the TF prevalence, a target sample size of 1701 (baseline) and 1164 1-9-year-olds (impact and surveillance) was required, whereas 2818 ≥ 15-year-olds were required to estimate the less prevalent TT. In each EU, individuals were selected by two-stage cluster sampling and examined by certified graders for TF and/or TT.

RESULTS

A total of 68,613 people were examined. TF prevalence estimates were under the 5% elimination threshold in all surveys. TT prevalence estimates were above the 0.2% elimination threshold in all five TT-only surveys and in four impact surveys, ranging from 0.2-0.57.

CONCLUSION

TF prevalence in Benin is low, but TT was above 0.2% in nine districts. Increased case-finding and continuing efforts to improve surgery accessibility will be needed to reduce the burden of TT in Benin.

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.

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.

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.

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.

Facial cleanliness indicators by time of day: results of a cross-sectional trachoma prevalence survey in Senegal

BACKGROUND

The World Health Organization-recommended strategy for trachoma elimination as a public health problem is known by the acronym "SAFE", where "F" stands for facial cleanliness to reduce transmission of ocular Chlamydia trachomatis infection. Accurately and reliably measuring facial cleanliness is problematic. Various indicators for measuring an unclean face exist, however, the accuracy and reliability of these indicators is questionable and their relationship to face washing practices is poorly described.

METHODS

Clean face indicator (ocular or nasal discharge, flies on the face, and dirt on the face), trachoma clinical sign, and ocular C. trachomatis infection data were collected for 1613 children aged 0-9 years in 12 Senegalese villages as part of a cross-sectional trachoma prevalence study. Time of examination was recorded to the nearest half hour. A risk factor questionnaire containing Water, Sanitation and Hygiene (WASH) questions was administered to heads of compounds (households that shared a common doorway) and households (those who shared a common cooking pot).

RESULTS

WASH access and use were high, with 1457/1613 (90.3%) children living in households with access to a primary water source within 30 min. Despite it being reported that 1610/1613 (99.8%) children had their face washed at awakening, > 75% (37/47) of children had at least one unclean face indicator at the first examination time-slot of the day. The proportion of children with facial cleanliness indicators differed depending on the time the child was examined. Dirt on the face was more common, and ocular discharge less common, in children examined after 11:00 h than in children examined at 10:30 h and 11:00 h.

CONCLUSIONS

Given the high reported WASH access and use, the proportion of children with an unclean face indicator should have been low at the beginning of the day. This was not observed, explained either by: the facial indicators not being reliable measures of face washing; eye discharge, nose discharge or dirt rapidly re-accumulated after face washing in children in this population at the time of fieldwork; and/or responder bias to the risk factor questionnaire. A high proportion of children had unclean face indicators throughout the day, with certain indicators varying by time of day. A reliable, standardised, practical measure of face washing is needed, that reflects hygiene behaviour rather than environmental or cultural factors.

Viability PCR shows that non-ocular surfaces could contribute to transmission of Chlamydia trachomatis infection in trachoma

Background

The presence of Chlamydia trachomatis (Ct) DNA at non-ocular sites suggests that these sites may represent plausible routes of Ct transmission in trachoma. However, qPCR cannot discriminate between DNA from viable and non-viable bacteria. Here we use a propodium monoazide based viability PCR to investigate how long Ct remains viable at non-ocular sites under laboratory-controlled conditions.

Methods

Cultured Ct stocks (strain A2497) were diluted to final concentrations of 1000, 100, 10 and 1 omcB copies/μL and applied to plastic, woven mat, cotton cloth and pig skin. Swabs were then systemically collected from each surface and tested for the presence Ct DNA using qPCR. If Ct DNA was recovered, Ct viability was assessed over time by spiking multiple areas of the same surface type with the same final concentrations. Swabs were collected from each surface at 0, 2, 4, 6, 8 and 24 hours after spiking. Viability PCR was used to determine Ct viability at each timepoint.

Results

We were able to detect Ct DNA on all surfaces except the woven mat. Total Ct DNA remained detectable and stable over 24 hours for all concentrations applied to plastic, pig skin and cotton cloth. The amount of viable Ct decreased over time. For plastic and skin surfaces, only those where concentrations of 100 or 1000 omcB copies/μL were applied still had viable loads detectable after 24 hours. Cotton cloth showed a more rapid decrease and only those where concentrations of 1000 omcB copies/μL were applied still had viable DNA detectable after 24 hours.

Conclusion

Plastic, cotton cloth and skin may contribute to transmission of the Ct strains that cause trachoma, by acting as sites where reservoirs of bacteria are deposited and later collected and transferred mechanically into previously uninfected eyes.

Trachoma elimination efforts are hampered by limited understanding of Ct transmission routes. We have recently demonstrated the presence of Ct DNA at non-ocular sites in individuals living in households in Ethiopia where at least one resident had an ocular Ct infection detectable by quantitative PCR (qPCR). Ct DNA was most frequently detected on faces, hands and clothing, being found in such locations in 10–16% of samples tested. However, qPCR cannot discriminate between DNA from viable and non-viable organisms, and potentially misinform our understanding of Ct transmission routes. In this study, we used a propidium monoazide based viability PCR to investigate how long Ct remains viable on non-ocular sites by spiking different surfaces including pig skin, plastic and cotton cloth. These surfaces mimic non-ocular sites previously found to be positive for Ct DNA using standard qPCR. The results of our study show that viable Ct DNA could be recovered from plastic, cotton cloth and skin surfaces for up to 24 hours suggesting that these surfaces a role in ocular Ct transmission.

Evidence for contamination with C. trachomatis in the household environment of children with active Trachoma: A cross-sectional study in Kongwa, Tanzania

Background

Trachoma, a conjunctivitis caused by repeated infections with Chlamydia trachomatis, remains a significant cause of blindness worldwide. While mass treatments with azithromycin decreases disease and infection, re-emergence occurs, indicating that elimination may require other sustainable interventions. Environmental changes largely focus on facial hygiene and latrines, but further work to identify other possible transmission targets are needed. We sought to determine, in a cross-sectional survey of households of children with active trachoma, if we could detect the presence of Chlamydia trachomatis on household objects and on family members based on sleeping and caretaking patterns.

Methods

In five villages in Kongwa, Tanzania, children <five years were randomly chosen for examination for trachoma, and households of all children with active trachoma (n = 90) were eligible for this study. We administered structured questionnaires of sleeping and caretaking habits. Based on the responses, environmental swabs of bedding, furniture, clothing, and hands were taken and processed using Amplicor for detecting C. trachomatis DNA.

Results

Of 80 visited households, 13 (16%) had at least one swab from environmental sources positive for C. trachomatis DNA. A positive environmental swab was associated with the presence of ocular infection in the index child (Odds Ratio = 22.0, p = .007), the presence of an infant <1 year of age in the household, and whether the children’s clothing had not been recently washed.

Conclusions

C. trachomatis DNA is present in the environment of children with active trachoma, especially in households with an ocular infection. Specific findings also suggest that washing hands, clothing, and bedding may be important.

Trachoma is the leading infectious cause of blindness world-wide. It is a conjunctivitis caused by repeated infections with Chlamydia trachomatis, spread from person to person by contact with infected ocular/nasal secretions. While mass treatment with azithromycin decreases infection, re-emergence occurs, indicating that elimination may require other sustainable interventions. Environmental changes largely focus on facial hygiene and latrines, but further work to identify other possible transmission targets is needed. In this cross-sectional study of households where at least one child has trachoma, we found evidence of C. trachomatis DNA on several environmental sources including clothing, bedsheets, furniture, and hands. Besides the presence of infection with C. trachomatis in the index child, chlamydial DNA in the environment was also associated with the presence of an infant in the household. Washing clothes within the past three days was associated with not having C. trachomatis DNA in the environment. Our study provides suggestive evidence that in high prevalence villages, C. trachomatis may be contaminating environmental objects, including hands and clothing. These findings suggest that behavior change communication around hygiene may need to be enlarged to focus on keeping ocular and nasal secretions off faces and hands, and promoting washing of clothing as well.

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.

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

Purpose: Surveys are needed to guide trachoma control efforts in Mozambique, with WHO guidelines for intervention based on the prevalence of trachomatous inflammation–follicular (TF) in children aged 1–9 years and the prevalence of trichiasis in adults aged 15 years and above. We conducted surveys to complete the map of trachoma prevalence in Mozambique.

Methods: Between July 2012 and May 2015, we carried out cross-sectional surveys in 96 evaluation units (EUs) covering 137 districts.

Results: A total of 269,217 individuals were enumerated and 249,318 people were examined using the WHO simplified trachoma grading system. Overall, 102,641 children aged 1–9 years, and 122,689 individuals aged 15 years and above were examined. The prevalence of TF in children aged 1–9 years was ≥10% in 12 EUs, composed of 20 districts, covering an estimated total population of 2,455,852. These districts require mass distribution of azithromycin for at least 3 years before re-survey. The TF prevalence in children was 5.0–9.9% in 17 EUs (28 districts, total population 3,753,039). 22 EUs (34 districts) had trichiasis prevalences ≥0.2% in adults 15 years and above, and will require public health action to provide surgical services addressing the backlog of trichiasis. Younger age, more children resident in the household, and living in a household that had an unimproved latrine or no latrine facility, were independently associated with an increased odds of TF in children aged 1–9 years.

Conclusions: Trachoma represents a significant public health problem in many areas of Mozambique.

Prevalence of Trachoma in Northern Benin: Results from 11 Population-Based Prevalence Surveys Covering 26 Districts

Aims

We sought to evaluate trachoma prevalence in all suspected-endemic areas of Benin.

Methods

We conducted population-based surveys covering 26 districts grouped into 11 evaluation units (EUs), using a two-stage, systematic and random, cluster sampling design powered at EU level. In each EU, 23 villages were systematically selected with population proportional to size; 30 households were selected from each village using compact segment sampling. In selected households, we examined all consenting residents aged one year or above for trichiasis, trachomatous inflammation – follicular (TF), and trachomatous inflammation – intense. We calculated the EU-level backlog of trichiasis and delineated the ophthalmic workforce in each EU using local interviews and telephone surveys.

Results

At EU-level, the TF prevalence in 1–9-year-olds ranged from 1.9 to 24.0%, with four EUs (incorporating eight districts) demonstrating prevalences ≥5%. The prevalence of trichiasis in adults aged 15+ years ranged from 0.1 to 1.9%. In nine EUs (incorporating 19 districts), the trichiasis prevalence in adults was ≥0.2%. An estimated 11,457 people have trichiasis in an area served by eight ophthalmic clinical officers.

Conclusion

In northern Benin, over 8000 people need surgery or other interventions for trichiasis to reach the trichiasis elimination threshold prevalence in each EU, and just over one million people need a combination of antibiotics, facial cleanliness and environmental improvement for the purposes of trachoma’s elimination as a public health problem. The current distribution of ophthalmic clinical officers does not match surgical needs.

The prevalence of chlamydia trachomatis among patients with acute conjunctivitis in Kasr Alainy ophthalmology clinic

INTRODUCTION

Trachoma is a leading cause of avoidable blindness and endemic conjunctivitis in 57 countries. It infects approximately 84 million people globally, and continues to threaten over 10% of the world's population with the risk of blindness.

METHODS

This is a cross sectional descriptive study assessing patients presenting with acute conjunctivitis. A full history was taken from patients followed by examination of both eyes. A conjunctival swab was taken and a sample of tears was collected and handled at the central laboratory unit at Kasr AlAiny hospital for culture and sensitivity of the swab and ELISA for tears searching for Immunoglobulin G and Immunoglobulin M of chlamydia trachomatis.

RESULTS

The prevalence of bacterial conjunctivitis encounted for 45.7% and non-bacterial 54.3% of the studied group. The anti-chlamydial antibodies were positive in the tears of 31.1% of patients. While the other bacterial organisms responsible for 14.6%.

CONCLUSION

The study concluded that trachoma accounts for one third of the cases of acute conjunctivitis while the other bacterial organisms responsible for about 14.6%. More than half of the cases have other causes as viral, allergic, mechanical or chemical induced conjunctivitis.

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.

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.

Efficacy of latrine promotion on emergence of infection with ocular Chlamydia trachomatis after mass antibiotic treatment: a cluster-randomized trial

The World Health Organization (WHO) recommends environmental improvements such as latrine construction in the integrated trachoma control strategy, SAFE. We report a cluster-randomized trial assessing the effect of intensive latrine promotion on emergence of infection with ocular Chlamydia trachomatis after mass treatment with antibiotics.Twenty-four communities in Goncha Seso Enesie woreda, Amhara Regional State, Ethiopia, were enumerated, and a random selection of 60 children aged 0- 9 years in each was monitored for clinical signs of trachoma and ocular chlamydial infection at baseline, 12 and 24 months. All community members were offered treatment with a single dose of oral azithromycin or topical tetracycline. After treatment, 12 subkebeles were randomized to receive intensive latrine promotion. Mean cluster ocular infection in the latrine and the non-latrine arms were reduced from 45.5% (95% CI 34.1-56.8%) and 43.0% (95% CI 31.1-54.8%) respectively at baseline to 14.6% (95% CI 7.4-21.8%) and 14.8% (95% CI 8.9-20.8%) respectively at 24 months (P=0.93). Clinical signs fell from 72.0% (95% CI 58.2-85.5%) and 61.3% (95% CI 44.0-78.5%) at baseline to 45.8% (36.0-55.6%) and 48.5% (34.0-62.9%) respectively at 24 months (P=0.69). At 24 months, estimated household latrine coverage and use were 80.8% and 61.7% respectively where there had been intensive latrine promotion and 30.0% and 25.0% respectively in the single treatment only arm. We were unable to detect a difference in the prevalence of ocular chlamydial infection in children due to latrine construction.

The association between latrine use and trachoma: a secondary cohort analysis from a randomized clinical trial

Latrine use has been promoted as a component of an integrated strategy for trachoma control. As part of a randomized trial in Ethiopia, 12 communities received a mass azithromycin distribution followed by a latrine promotion intervention. A random sample of children ages 0-9 years in each community was monitored longitudinally for ocular chlamydia. After latrine construction ended, those communities with a higher proportion of households using latrines were more likely to experience a reduction in the prevalence of ocular chlamydia. Specifically, for each 10% increase in latrine use, there was a 2.0% decrease (95% confidence interval = 0.2-3.9% decrease) in the community prevalence of ocular chlamydia over the subsequent year (P = 0.04).

Prevalence of and risk factors for trachoma in Kano state, Nigeria

Background

In northern Nigeria, trachoma is an important public health problem, but there are currently few population-based data on prevalence of disease and no formal trachoma control programs.

Methodology / Principal Findings

In Kano state, Nigeria, we conducted a population-based cross-sectional survey using multistage cluster random sampling, combining examination for clinical signs of trachoma and application of questionnaires assessing potential household-level risk factors. A total of 4491 people were examined in 40 clusters, of whom 1572 were aged 1–9 years, and 2407 (53.6%) were female. In 1–9 year-olds, the prevalence of trachomatous inflammation–follicular (TF) was 17.5% (95% CI: 15.7–19.5%). In a multivariate model, independent risk factors for active trachoma were the presence of flies on the face (OR 1.98, 95% CI 1.30–3.02); a dirty face (OR 2.45, 95% CI 1.85–3.25) and presence of animal dung within the compound of residence (OR 3.46, 95% CI 1.62–7.41). The prevalence of trachomatous trichiasis in persons aged ≥15years was 10.9% (95% CI: 9.7–12.2%). Trichiasis was significantly more common in adult females than in adult males.

Conclusion/Significance

There is an urgent need for a trachoma control program in Kano state, with emphasis given to provision of good quality trichiasis surgery. Particular effort will need to be made to identify women with trichiasis and engage them with appropriate services while also taking steps to secure azithromycin for mass treatment and ensuring personal and environmental hygiene.

Integrated monitoring and evaluation and environmental risk factors for urogenital schistosomiasis and active trachoma in Burkina Faso before preventative chemotherapy using sentinel sites

Background

Over 1 billion of the world's poorest inhabitants are afflicted by neglected tropical diseases (NTDs). Integrated control programmes aimed at tackling these debilitating NTDs have been recently initiated, mainly using preventative chemotherapy. Monitoring and evaluation (M&E) of these integrated programs presents particular challenges over and above those required for single disease vertical programmes. We used baseline data from the National NTD Control Programme in Burkina Faso in order to assess the feasibility of an integrated survey design, as well as to elucidate the contribution of environmental variables to the risk of either Schistosoma haematobium, trachoma, or both among school-aged children.

Methods

S. haematobium infection was diagnosed by detecting eggs in urine. A trachoma case was defined by the presence of Trachomatous inflammation-Follicular (TF) and/or Trachomatous inflammation-Intense (TI) in either eye. Baseline data collected from 3,324 children aged 7-11 years in 21 sentinel sites across 11 regions of Burkina Faso were analyzed using simple and multivariable hierarchical binomial logistic regression models fitted by Markov Chain Monte Carlo estimation methods. Probabilities of the risk of belonging to each infection/disease category were estimated as a function of age, gender (individual level), and environmental variables (at sentinel site level, interpolated from national meteorological stations).

Results

Overall prevalence at the sentinel sites was 11.79% (95% CI: 10.70-12.89) for S. haematobium; 13.30% (12.14-14.45) for trachoma and 0.84% (0.53-1.15) for co-infections. The only significant predictor of S. haematobium infection was altitude. There were significant negative associations between the prevalence of active trachoma signs and minimum temperature, and air pressure. Conditional upon these predictors, these data are consistent with the two pathogens being independent.

Conclusions

Urogenital schistosomiasis and trachoma constitute public health problems in Burkina Faso. Sentinel site (at school level) surveys for these two NTDs can be implemented simultaneously. However, to support MDA treatment decisions in Burkina Faso, the protocol used in this study would only be applicable to hypoendemic trachoma areas. More research is needed to confirm if these findings can be generalized to West Africa and beyond.

Prevalence and risk factors for near and far visual difficulty in Burkina Faso

PURPOSE

To determine the prevalence and risk factors for near and far visual difficulty in Burkina Faso.

METHODS

Population-based data were used from the World Health Survey done in Burkina Faso in 2002-2003;2003 (n=4,822 adults). Near and far visual difficulty were assessed by questions about difficulty seeing and recognizing an object at arm's length and about difficulty seeing and recognizing a person across the road. Prevalence estimates were adjusted for the multi-stage, stratified, random cluster sampling design. Logistic regression was used to identify independent risk factors.

RESULTS

The overall prevalence of any near and far visual difficulty was 10% (standard error [SE] = 0.7%) and 13% (SE=0.9%) respectively. Prevalence estimates were strongly associated with age with 48% (SE=4.2%) and 66% (SE=3.9%) of those >or= 65 years old having near or far visual difficulty (P < 0.001). Only 5% (SE=0.6%) of people wore glasses. We identified two potentially modifiable variables associated with near visual difficulty: a cooking stove in the same room as sleeping area (Odds Ratio [OR]=1.45, 95% Confidence Interval [CI] 1.01, 2.02) and high fruit consumption (OR=0.65, 95% CI 0.50, 0.86).

CONCLUSION

The prevalence of visual difficulty was high in Burkina Faso. Efforts to confirm these findings with cooking stove location and fruit consumption should be undertaken in this population.

Active trachoma among children in Mali: Clustering and environmental risk factors

BACKGROUND

Active trachoma is not uniformly distributed in endemic areas, and local environmental factors influencing its prevalence are not yet adequately understood. Determining whether clustering is a consistent phenomenon may help predict likely modes of transmission and help to determine the appropriate level at which to target control interventions. The aims of this study were, therefore, to disentangle the relative importance of clustering at different levels and to assess the respective role of individual, socio-demographic, and environmental factors on active trachoma prevalence among children in Mali.

METHODOLOGY/PRINCIPAL FINDINGS

We used anonymous data collected during the Mali national trachoma survey (1996-1997) at different levels of the traditional social structure (14,627 children under 10 years of age, 6,251 caretakers, 2,269 households, 203 villages). Besides field-collected data, environmental variables were retrieved later from various databases at the village level. Bayesian hierarchical logistic models were fit to these prevalence and exposure data. Clustering revealed significant results at four hierarchical levels. The higher proportion of the variation in the occurrence of active trachoma was attributable to the village level (36.7%), followed by household (25.3%), and child (24.7%) levels. Beyond some well-established individual risk factors (age between 3 and 5, dirty face, and flies on the face), we showed that caretaker-level (wiping after body washing), household-level (common ownership of radio, and motorbike), and village-level (presence of a women's association, average monthly maximal temperature and sunshine fraction, average annual mean temperature, presence of rainy days) features were associated with reduced active trachoma prevalence.

CONCLUSIONS/SIGNIFICANCE

This study clearly indicates the importance of directing control efforts both at children with active trachoma as well as those with close contact, and at communities. The results support facial cleanliness and environmental improvements (the SAFE strategy) as population-health initiatives to combat blinding trachoma.

Assessment of latrine use and quality and association with risk of trachoma in rural Tanzania

The existing evidence regarding latrines and trachoma is inconclusive. Using more precise sanitation measures we examine the association between use and quality of latrines and risk of trachoma. We conducted a case-control study of 678 households (95 cases, 583 controls) in eight villages in Kongwa District, Tanzania. Case households were defined as having a sentinel child with clinical signs of trachoma. A latrine quality score was calculated based on seven indicators and case and control households were compared with respect to use and quality of latrines. Logistic regression analyses controlled for potential confounders. Latrine use was significantly greater in control households than in case households (90.4 vs. 76.8%, P=0.03). The protective effect of latrine use persisted even after controlling for household characteristics significant at P <0.20 (adjusted OR=0.56 [95% CI: 0.32-0.98]). Contrary to expectation, we did not find an inverse association between increasing latrine quality and decreasing odds of trachoma. Although latrine use in the communities was high, latrines, regardless of quality, were significantly associated with decreased risk of trachoma. These findings underscore the importance of achieving 100% latrine use in communities.

Strategies to control trachoma

Trachoma is a significant public health problem that is endemic in 57 countries, affecting 40.6 million people and contributing to 4% of the global burden of blindness. Repeated episodes of infection from Chlamydia trachomatis lead to long-term inflammation, scarring of the tarsal conjunctiva and distortion of the upper eyelid with in-turning of eyelashes that abrade the surface of the globe. This constant abrasion, in turn, can cause irreversible corneal opacity and blindness. The Alliance for the Global Elimination of Trachoma by 2020 (GET2020) has adopted the SAFE (Surgery, Antibiotics, Facial cleanliness and Environmental improvement) strategy as the main action against trachoma. Trichiasis surgery reduces the risk of blindness by reversing the in-turning of eyelashes and also improves the quality of life from non-visual symptoms. However, future efforts need to aim at increasing accessibility to surgery and improving acceptance. Antibacterials are required to reduce the burden of infection. Oral azithromycin is as close to the perfect antibacterial as we will get for mass distribution: it is safe, requires only a single oral dose, treatment is usually repeated every 6-12 months, resistance is not seen as a problem, and cost is not a limiting factor with a large donation programme and newer generic versions of the drug. Future focus should be on the details of antibacterial distribution such as coverage, frequency of distribution and target population. The promotion of facial cleanliness through education may be the key to trachoma elimination as it will stop the frequent exchange of infected ocular secretions and thus reduce the transmission of infection. However, innovative methods are required to translate health education and promotion activities into sustainable changes in hygiene behaviour. Environmental improvements should focus on the barriers to achieving facial cleanliness and cost-effective means need to be identified. There are a number of countries already eligible for certification of trachoma elimination and if current momentum continues, blinding trachoma can be eliminated by the year 2020.

Trachoma survey methods: a literature review

Reliable population-based prevalence data are essential for planning, monitoring and evaluating trachoma control programmes and understanding the scale of the problem, yet they are not currently available for 22 out of 56 trachoma-endemic countries. Three survey methods have been advocated for trachoma: cluster random sampling (CRS); trachoma rapid assessment (TRA); and acceptance sampling trachoma rapid assessment (ASTRA). Our review highlights the benefits of CRS being simple, efficient, repeatable and giving population-based prevalence estimates of all signs of trachoma. There are limitations to TRA, which include: non-representative sampling; does not estimate prevalence; and lacks consistency and accuracy. ASTRA advocates small sample sizes but it is relatively complex, may result in imprecise prevalence estimates and does not estimate cicatricial signs of trachoma. We conclude that CRS should therefore remain the 'gold' standard for trachoma surveys. However, among the CRS surveys reviewed, we also found several methodological deficiencies of sample-size calculations, standardization of trachoma graders, reporting of confidence intervals of prevalence estimates, variability of age groups for presentation of age-specific prevalence, and lack of estimation of district prevalence estimates. Properly conducted surveys will be crucial if the objective of global elimination of blinding trachoma is to be charted and realized. Harmonization of survey methods will enhance the conduct and comparability of trachoma surveys needed for reliable mapping of prevalence within endemic countries. Consistent with WHO recommendations, we advocate for continued use of CRS as the survey design of choice for trachoma control programmes and propose ways of improving future surveys based on this method.

The burden of trachoma in Ayod County of Southern Sudan

Background

Blindness due to trachoma is avoidable through Surgery, Antibiotics, Facial hygiene and Environmental improvements (SAFE). Recent surveys have shown trachoma to be a serious cause of blindness in Southern Sudan. We conducted this survey in Ayod County of Jonglei State to estimate the need for intervention activities to eliminate blinding trachoma.

Methodology and Findings

A cross-sectional two-stage cluster random survey was conducted in November 2006. All residents of selected households were clinically assessed for trachoma using the World Health Organization (WHO) simplified grading scheme. A total of 2,335 people from 392 households were examined, of whom 1,107 were over 14 years of age. Prevalence of signs of active trachoma in children 1–9 years of age was: trachomatous inflammation follicular (TF) = 80.1% (95% confidence interval [CI], 73.9–86.3); trachomatous inflammation intense (TI) = 60.7% (95% CI, 54.6–66.8); and TF and/or TI (active trachoma) = 88.3% (95% CI, 83.7–92.9). Prevalence of trachomatous trichiasis (TT) was 14.6% (95% CI, 10.9–18.3) in adults over 14 years of age; 2.9% (95% CI, 0.4–5.3) in children 1–14 years of age; and 8.4% (95% CI, 5.5–11.3) overall. The prevalence of corneal opacity in persons over 14 years of age with TT was 6.4% (95% CI, 4.5–8.3). No statistically significant difference was observed in the prevalence of trachoma signs between genders. Trachoma affected almost all households surveyed: 384/392 (98.0%) had at least one person with active trachoma and 130 (33.2%) had at least one person with trichiasis.

Conclusions

Trachoma is an unnecessary public health problem in Ayod. The high prevalence of active trachoma and trichiasis confirms the severe burden of blinding trachoma found in other post-conflict areas of Southern Sudan. Based on WHO recommended thresholds, all aspects of the SAFE strategy are indicated to eliminate blinding trachoma in Ayod.

Trachoma, a neglected tropical disease, is the leading cause of infectious blindness and is targeted for global elimination by the year 2020. We conducted a survey in Ayod County of Jonglei State, Southern Sudan, to determine whether blinding trachoma was a public health problem and to plan interventions to control this disease. We found the burden of trachoma in Ayod to be one of the most severe ever documented. Not only were adults affected by the advanced manifestations of the disease as is typical for older age groups, but young children were also affected. At least one person with clinical signs of trachoma was found in nearly every household, and 1 in 3 households had a person with severe blinding trachoma. Characteristics previously identified as risk factors were ubiquitous among surveyed households, but we were unable to identify why trachoma is so severe in this location. Surgical interventions are needed urgently to improve vision and prevent irreversible blindness in children and adults. Mass antibiotic distribution may alleviate current infections and transmission of trachoma may be reduced if communities adopt the behavior of face washing and safe disposal of human waste. Increasing access to improved water sources may not only improve hygiene but also reduce the spread of guinea worm and other water-borne diseases.

Issues in defining and measuring facial cleanliness for national trachoma control programs

The WHO trachoma control strategy includes promotion of facial cleanliness to interrupt transmission. However, scant data exist on measuring a clean face. Our goals were to determine reliable indicators of a clean face in a child, and disparities between the assessments of faces at a clinic versus at home. Five hallmarks of a clean face were assessed on 50 children in Tanzania. In five districts, 973 children (age 1-5 years) were evaluated for facial cleanliness at home, and again 2 days later at a central location for a trachoma examination. Data on environmental risk factors were collected. Only three signs, ocular and nasal discharge, and flies on the face, were reliable indicators of facial cleanliness (kappa>0.6); dust and food were less reliable. Unclean faces were more prevalent when measured at home (62%) than at the clinic (51%), although both were related to trachoma. The environmental markers of absence of latrines and tin roofs were consistent markers across all districts of households at risk of poor facial cleanliness. We conclude that for accurate estimates of clean faces, some assessment strategy outside the clinical environment is necessary. Additionally, behavior change programs in these districts in Tanzania should especially target families without tin roofs or latrines.

Risk factors for active trachoma and Chlamydia trachomatis infection in rural Ethiopia after mass treatment with azithromycin

OBJECTIVES

To investigate risk factors for ocular Chlamydia trachomatis infection and active trachoma, comparing communities receiving or not receiving an intervention programme of community-wide azithromycin treatment and health education.

METHODS

In a 3-year post-intervention follow-up survey, 1722 children aged 3-9 years, from randomly selected households in 37 communities, were examined for signs of active trachoma and had samples taken to test for ocular C. trachomatis by polymerase chain reaction. Multivariate random effects logistic regression analyses considered interventions at community level, adjusting for other independent risk factors as appropriate.

RESULTS

Younger age, ocular discharge and flies on eyes were risk factors for active trachoma in communities with and without antibiotic treatment. After azithromycin treatment, odds of active trachoma were lower in children aged 6-9 years than in children aged 3-5 years (OR 0.48, 95% CI: 0.36-0.66) and higher for children with ocular discharge (OR 4.5, 95% CI: 2.6-7.7) or flies on their eyes (OR 2.5, 95% CI: 1.6-3.7). Odds of C. trachomatis infection were lower in children aged 6-9 years than in younger children (OR 0.47, 95% CI: 0.23-0.96); and in children who received 2 or 3 doses rather than 1 (OR 0.26, 95% CI: 0.08-0.88).

CONCLUSIONS

In communities that received or did not receive the mass antibiotic treatment, the same risk factors for C. trachomatis and active trachoma were identified. Education and environmental improvements need to supplement antibiotic campaigns in order to positively impact on these remaining child level risk factors.

Seasonal and altitudinal variations in fly density and their association with the occurrence of trachoma, in the Gurage zone of central Ethiopia

In the Gurage zone of central Ethiopia, the association between fly density and the occurrence of trachoma has been investigated across varying altitudes. The seasonal pattern of fly density in the area was also explored. When, over short sampling periods (10 min/child indoors and 10 min/child outdoors), hand nets were used to collect flies from the eyes of children aged 2-8 years, only Musca sorbens and M. domestica were caught. Almost all of the 13,147 'eye-seeking' flies collected came from villages at low (<2000 m; 40.7%) or mid altitudes (2200-2500 m; 58.6%) with only 0.7% of them caught in the high-altitude villages investigated (at >3000 m). Musca sorbens predominated outdoors and M. domestica indoors. Almost all (99.3%) of the eye-seeking M. sorbens collected were caught outdoors whereas most (76.7%) of the M. domestica were caught indoors (P<0.0001 for each). The median numbers of flies caught, per child, per 10-min collection, in the low-, mid- and high-altitude villages were 9.5, six and zero, respectively, for M. sorbens, and eight, three and zero, respectively, for M. domestica. The altitudinal trends in these numbers of 'eye-seeking' flies matched those in the prevalences of active trachoma among children aged 1-10 years, which were high in the villages at low (81.6%) and mid altitude (78.7%) but much lower (1.7%) in the high-altitude villages. In conclusion, trachoma is a common disease of public-health importance only in the low- and mid-altitude villages in the Gurage zone, where there are large numbers of eye-seeking flies, and not in the villages that lie >3000 m above sea level, where there is a dearth of such flies.

Trichiasis and geoclimatic factors in Mali

Several trachoma surveys conducted in sub-Saharan countries showed different geographical distributions of active trachoma and trichiasis. Trichiasis is more common in southern regions. We analysed the role of geoclimatic factors in determining the distributions of active trachoma and trichiasis in Mali. In each region a random sample of 30 clusters was examined. The prevalence of active trachoma among children and of trichiasis among women was compared, and geographical, environmental and social risk factors were assessed. Logistic regression models were constructed. Multiple regression analysis was applied and models were used to map the probability of active trachoma and trichiasis. The highest prevalence rates of active trachoma (TF/TI) were found in the northern part of Mali reaching 41.1% among children living north of the 15th parallel. Surprisingly, prevalence rates of trichiasis (TT) among women regularly increased from north to south (1.0% north of the 15th parallel vs. 2.8% south; OR=2.91, 95% CI 2.01-4.24). The two related predictive maps showed a gradient SSE/NNW for TF/TI very different from the gradient NS/SW for TT. These opposite spatial distributions could be explained by differences in the pathogenic agent, the natural history of the disease, population susceptibility, grading process or vulnerable group behaviour.

Prevalence and risk factors for trachoma and ocular Chlamydia trachomatis infection in Niger

AIMS

To determine the association of personal and household risk factors for trachoma and ocular Chlamydia trachomatis infection in Niger.

METHODS

12 villages were randomly selected. A census of all households was carried out, and 651 children aged 1-5 years were randomly selected and examined. Household and personal characteristics were determined, trachoma was clinically assessed and a swab for ocular C trachomatis infection was taken.

RESULTS

The prevalence of trachoma was 43% (95% confidence interval (CI) 39% to 47%) and of infection was 21% (95% CI 18% to 24%). Children aged 3-5 years had a stronger association of clinical signs with infection, compared with those aged 1-2 years. Those with unclean faces were three times more likely to have clinical trachoma or ocular C trachomatis infection, compared with those with clean faces (OR 3.1 (95% CI 1.6 to 6.2) and 3.0 (95% CI 1.4 to 6.3), respectively). 75% of compounds were within 30 min of a water source. Flies on the face were a risk factor for trachoma but not for C trachomatis infection.

CONCLUSIONS

The different association of clinical signs with infection in younger versus older children may be an age-dependent difference in the duration of clinical disease. In Niger, unclean faces are a major risk factor for trachoma. The ready availability of water for washing suggests that further research on the effect of a strong health education campaign promoting clean children is warranted in this area.

Impact of health education on active trachoma in hyperendemic rural communities in Ethiopia

OBJECTIVE

Trachoma is one of the leading preventable causes of blindness worldwide. We evaluate the impact of a health education program on the prevalence of active trachoma in children 3 to 9 years old.

DESIGN

Community randomized intervention study. Data were collected by means of cross-sectional surveys before and after intervention.

PARTICIPANTS

Within 40 rural Ethiopian communities, households were selected at random, and all 3- to 9-year-old children within households were invited for examination.

METHODS

Health education messages broadcast by radio were received by all communities. Nongovernmental organization activities to prevent trachoma, based on the SAFE (surgery for trichiasis, antibiotic treatment, face washing, and environmental improvements) strategy, were received by 30 of the 40 communities. Ten of these communities received enhanced educational messages using videos. Cluster summary measures were compared across surveys and intervention arms. Active trachoma at follow-up was modeled using random-effects logistic regression, adjusting for baseline prevalence and study area variability, at the cluster and individual level.

MAIN OUTCOME MEASURES

Active trachoma in 3- to 9-year-old children and adult knowledge and behavior related to the nature and transmission of trachoma infection.

RESULTS

At baseline, 1410 of 1960 (72%) children examined and, at follow-up, 1289 of 2008 (64%) had active trachoma. The overall reduction in prevalence at cluster level was 8% (95% confidence interval [CI], 4%-12%; P<0.001). There was a statistically significant increase in the awareness of trachoma. After adjustment for area and cluster level baseline prevalence, the odds of active trachoma were reduced in both intervention arms, standard (odds ratio [OR], 0.78; 95% CI, 0.53-1.16) and enhanced (OR, 0.76; 95% CI, 0.48-1.21), compared with the control arm, but not significantly.

CONCLUSIONS

Overall, there was a small but statistically significant reduction in the prevalence of active trachoma between surveys, but differences between the 3 intervention arms were not statistically significant. Awareness of trachoma control increased in all communities, but there was little change in behavior associated with the transmission of Chlamydia trachomatis. It is therefore unlikely that observed reductions in active trachoma were solely due to health education.

[Factors associated with trachoma in a low-endemic area in southeast Brazil]

A case-control study matched by age and school (n=121 pairs) was carried out among pre-elementary and elementary students from low-income families living in Greater Metropolitan São Paulo, Brazil, with the objective of investigating factors associated with trachoma in a low prevalence area. The case definition for trachoma was that proposed by the World Health Organization. The dependent variable was trachoma and the independent variables were social stratum, housing of migrants from endemic areas, facial hygiene habits, head of family's schooling, access to potable water, contact with another case in the family, and slum residence. Unadjusted and adjusted odds ratios (OR), with their respective 95% confidence intervals (95%CI), were estimated by conditional logistic regression. In the multivariate analysis, belonging to the poorest social stratum (OR = 8.21; 95%CI: 1.50-44.81), housing people from endemic areas (OR = 2.44; 95%CI: 1.10-5.46), contact with another case in the family (OR = 2.52; 95%CI: 0.98-6.48), and facial hygiene habits (OR = 0.50; 95%CI: 0.26-0.98) were independently associated with trachoma.

Contribution of sex-linked biology and gender roles to disparities with trachoma

Globally, trachoma is the leading infectious cause of blindness. Survey data consistently show that trachoma-related blindness is two to four times higher in women than men. Tracing the increased risk for trachoma and its consequences for women suggests that other factors besides biology may contribute. Understanding the reasons for the excess risk for and consequences of trachoma in girls and women requires examining a number of issues: Are girls and women more biologically susceptible to the consequences of infection with Chlamydia trachomatis? Could other factors help explain the excess of conjunctival scarring and trichiasis in women? Do gender roles affect the risk for trachoma and its consequences? Are women more likely to have recurrence after trichiasis surgery compared to men? This article explores the answers to these questions.

Role of flies and provision of latrines in trachoma control: cluster-randomised controlled trial

BACKGROUND

Eye-seeking flies have received much attention as possible trachoma vectors, but this remains unproved. We aimed to assess the role of eye-seeking flies as vectors of trachoma and to test provision of simple pit latrines, without additional health education, as a sustainable method of fly control.

METHODS

In a community-based, cluster-randomised controlled trial, we recruited seven sets of three village clusters and randomly assigned them to either an intervention group that received regular insecticide spraying or provision of pit latrines (without additional health education) to each household, or to a control group with no intervention. Our primary outcomes were fly-eye contact and prevalence of active trachoma. Frequency of child fly-eye contact was monitored fortnightly. Whole communities were screened for clinical signs of trachoma at baseline and after 6 months. Analysis was per protocol.

FINDINGS

Of 7080 people recruited, 6087 (86%) were screened at follow-up. Baseline community prevalence of active trachoma was 6%. The number of Musca sorbens flies caught from children's eyes was reduced by 88% (95% CI 64-100; p<0.0001) by insecticide spraying and by 30% (7-52; p=0.04) by latrine provision by comparison with controls. Analysis of age-standardised trachoma prevalence rates at the cluster level (n=14) showed that spraying was associated with a mean reduction in trachoma prevalence of 56% (19-93; p=0.01) and 30% with latrines (-81 to 22; p=0.210) by comparison with the mean rate change in the controls.

INTERPRETATION

Fly control with insecticide is effective at reducing the number of flies caught from children's eyes and is associated with substantially lower trachoma prevalence compared with controls. Such a finding is consistent with flies being important vectors of trachoma. Since latrine provision without health education was associated with a significant reduction in fly-eye contact by M sorbens, studies of their effect when combined with other trachoma control measures are warranted.