Risk factors for trichiasis in women in Kongwa, Tanzania: a case-control study

Meandered and muddled: a systematic review on the impact of air pollution on ocular health

From the years 1970-2023, a systematic overview of the diverse consequences of particulate matter on eye health and a disease classification according to acute, chronic, and genetic are presented using the PubMed, Research Gate, Google Scholar, and Science Direct databases. Various studies on medical aspects correlate with the eye and health. However, from an application perspective, there is limited research on the ocular surface and air pollution. The main objective of the study is to uncover the relationship between eye health and air pollution, particularly particulate matter, along with other external factors acting as aggravators. The secondary goal of the work is to examine the existing models for mimicking human eyes. The study is followed by a questionnaire survey in a workshop, in which the exposure-based investigation was tagged based on their activity. This paper establishes a relationship between particulate matter and its influence on human health, leading to numerous eye diseases like dry eyes, conjunctivitis, myopia, glaucoma, and trachoma. The results of the questionnaire survey indicate that about 68% of the people working in the workshop are symptomatic with tears, blurred vision, and mood swings, while 32% of the people were asymptomatic. Although there are approaches for conducting experiments, the evaluation is not well defined; empirical and numerical solutions for particle deposition on the eye are needed. There prevails a broad gap in the arena of ocular deposition modeling.

Risk factors for the progression of trachomatous scarring in a cohort of women in a trachoma low endemic district in Tanzania

Background

Trachoma, a chronic conjunctivitis caused by Chlamydia trachomatis, is the leading infectious cause of blindness worldwide. Trachoma has been targeted for elimination as a public health problem which includes reducing trachomatous inflammation—follicular prevalence in children and reducing trachomatous trichiasis prevalence in adults. The rate of development of trachomatous trichiasis, the potentially blinding late-stage trachoma sequelae, depends on the rate of trachomatous scarring development and progression. Few studies to date have evaluated the progression of trachomatous scarring in communities that have recently transitioned to a low trachomatous inflammation—follicular prevalence.

Methodology/Principal findings

Women aged 15 and older were randomly selected from households in 48 communities within Kongwa district, Tanzania and followed over 3.5 years for this longitudinal study. Trachomatous inflammation—follicular prevalence was 5% at baseline and at follow-up in children aged 1–9 in Kongwa, Tanzania. 1018 women aged 15 and older had trachomatous scarring at baseline and were at risk for trachomatous scarring progression; 691 (68%) completed follow-up assessments. Photographs of the upper tarsal conjunctiva were obtained at baseline and follow-up and graded for trachomatous scarring using a previously published four-step severity scale. The overall cumulative 3.5-year progression rate of scarring was 35.3% (95% CI 31.6–39.1). The odds of TS progression increased with an increase in age in women younger than 50, (OR 1.03, 95% CI 1.01–1.05, p = 0.005) as well as an increase in the household poverty index (OR 1.29, 95% CI 1.13–1.48, p = 0.0002).

Conclusions/Significance

The 3.5-year progression of scarring among women in Kongwa, a formerly hyperendemic now turned hypoendemic district in central Tanzania, was high despite a low active trachoma prevalence. This suggests that the drivers of scarring progression are likely not related to on-going trachoma transmission in this district.

Trachoma, a chronic conjunctivitis caused by Chlamydia trachomatis, presents with follicles (trachomatous inflammation—follicular, TF) in children which leads to trachomatous conjunctival scarring (TS) in young adults. TS can progress to the in-turning of eyelashes, trachomatous trichiasis (TT) which places individuals at high risk of irreversible vision loss. Few studies to date have evaluated the progression of TS in communities that have recently transitioned to a low trachoma prevalence.

We studied the progression of TS in women in Kongwa, Tanzania a district that recently transitioned to a low prevalence of trachoma. We found that the overall cumulative progression of scarring was 35.3% over 3.5 years. The scarring progression rate observed is very similar to what we observed a decade prior in Kongwa when the trachoma prevalence was very high.

Our findings suggest that once scarring has developed it continues to progress irrespective of the current trachoma environment. This has potential ramifications for trachoma elimination efforts. An area could achieve the elimination of TF and still have to deal with scarring progression, which may lead to the development of TT. If this occurs: 1) elimination of TT will be delayed which will delay the overall elimination of trachoma as a public health problem, and 2) the limited resources available to elimination programs may need to be re-allocated.

Risk factors for incidence of trachomatous scarring in a cohort of women in low endemic district

BACKGROUND/AIMS

To determine the incidence of scarring in women in a trachoma low endemic district of rural Tanzania and to determine the effects of lifetime cooking fire exposure and markers of lower socioeconomic status on incidence of scarring in these women.

METHODS

A prospective cohort study was conducted over a 3.5-year period from 2013 to 2016 in 48 villages in Kongwa, Tanzania where trachoma at baseline was 5.2% in children. A random sample of 2966 women aged 15 and older who were at risk for incident scarring were eligible for follow-up. Data on demographic factors, cooking fire exposure and trachomatous scarring were gathered at baseline and follow-up. An index of lifetime exposure to cooking fire exposure was created and bivariate analysis, age-adjusted logistic regression and multivariable logistic models were used to look for associations of demographic factors and cooking fire exposure with incident trachomatous scarring.

RESULTS

The cumulative incidence of scarring was 7.1% or 2.0% per year. Incidence of scarring increased with age and exposure to markers of lower socioeconomic status. A multivariable logistic regression model adjusting for confounding factors did not find an association between lifetime cooking fire exposure and incidence of scarring (OR=0.92; 95% CI 0.68 to 1.24, P=0.58).

CONCLUSIONS

There was still incident scarring in women in Tanzania despite low rates of active trachoma. There was no association between exposure to cooking fires and incident scarring. More research is needed to understand the factors that contribute to new scarring in these women.

Genetic Polymorphisms of TLR4 and MICA are Associated with Severity of Trachoma Disease in Tanzania

Aim

To examine the association of TLR4 Asp299Gly and MICA exon 5 microsatellites polymorphisms with severity of trachoma in a sub-Saharan East Africa population of Tanzanian villagers.

Methods

The samples were genotyped for MICA exon 5 microsatellites and the TLR4 299 A/G polymorphism by Restriction Fragment Length Polymorphism (RFLP), and GeneScan^®, respectively. The association of TLR4 Asp299Gly and MICA exon 5 microsatellites with inflammatory trachoma (TI) and trichiasis (TI) were examined.

Results

The results showed an association between TLR4 and MICA polymorphisms and trachoma disease severity, as well as with protection. TLR4 an allele was significantly associated with inflammatory trachoma (p=0.0410), while the G allele (p=0.0410) was associated with protection.

Conclusion

TLR4 and MICA may modulate the risk of severity to trachoma disease by modulating the immune response to Ct. In addition; the increased frequency of MICA-A9 heterozygote in controls may suggest a positive selection of these alleles in adaptation to environments where Ct is endemic.

The limits of medical interventions for the elimination of preventable blindness

Background: Health authorities are working toward the global elimination of trachoma by the year 2020 with actions focused on the World Health Organization SAFE strategy (surgery of trichiasis, antibiotics, face washing and environmental changes) with emphasis on hygienist approaches for education.

Objectives: The present survey was performed to assess the sustainability of the SAFE strategy 3 years after trachoma was eliminated from 6 villages.

Methods: In February 2013 a rapid trachoma assessment was conducted in 6 villages of Kolofata’s district, Extreme north Region, Cameroon, where trachoma was eliminated in 2010. A total of 300 children (1–10 years) from 6 villages were examined by trained staff.

Results: The prevalence of active trachoma (children aged > 1 and < 10 years) in 2013 was 15% and in at least 25% was observed absence of face washing and flies in their eyes and nose. Income level, quality of roads, hygiene, and illiteracy were similar in all the villages; they did not change between 2010 and 2013 and could not be analyzed as independent risk factors.

Discussion: The heterogeneity of methods described for clinical trials makes it inappropriate to conduct meta-analysis for the present and for other SAFE-related trials. The results obtained after implementation the SAFE strategy (recurrence) reveal that the causes (infectious agents and dirtiness) and effects (illness) were not connected by illiterate people living under conditions of extreme poverty. So far, antibiotics, surgery and hygiene education are insufficient for the sustainability of trachoma elimination and highlight that hypothetic-deductive processes seem not operational after implementing the awareness campaigns. Trachoma recurrence detected in 2013 in sedentary populations of Kolofata receiving efficacious treatments against Chlamydia sp. suggest that the elimination goals will be delayed if strategies are limited to medical actions. Restricting efforts to repeated pharmacological and surgical interventions for people infected with susceptible bacteria could be understood as the hidden side of a passive attitude toward basic education actions.

Is household air pollution a risk factor for eye disease?

In developing countries, household air pollution (HAP) resulting from the inefficient burning of coal and biomass (wood, charcoal, animal dung and crop residues) for cooking and heating has been linked to a number of negative health outcomes, mostly notably respiratory diseases and cancers. While ocular irritation has been associated with HAP, there are sparse data on adverse ocular outcomes that may result from acute and chronic exposures. We consider that there is suggestive evidence, and biological plausibility, to hypothesize that HAP is associated with some of the major blinding, and painful, eye conditions seen worldwide. Further research on this environmental risk factor for eye diseases is warranted.

Household air pollution in low- and middle-income countries: health risks and research priorities

William Martin and colleagues report on their stakeholder meetings that reviewed the health risks of household air pollution and cookstoves, and identified research priorities in seven key areas. Please see later in the article for the Editors' Summary

Active trachoma and associated risk factors among children in Baso Liben District of East Gojjam, Ethiopia

Background

Trachoma is the leading cause of preventable blindness worldwide. It is common in areas where the people are socio-economically deprived. The aim of this study was to assess active trachoma and associated risk factors among children 1–9 years in East Gojjam.

Methods

Community-based cross-sectional study was conducted in Baso Liben District from February to April 2012. A two-stage random cluster-sampling technique was employed and all children 1–9 years old from each household were clinically assessed for trachoma based on simplified WHO 1983 classification. Data were collected by using semi-structured interview, pre-tested questionnaire and observation. The data were entered and analyzed using SPSS version 16 statistical package.

Results

From a total of 792 children screened for trachoma (of which 50.6% were girls), the overall prevalence of active trachoma was 24.1% consisting of only 17.2% [95% CI: 14.8, 20.1] TF and 6.8% TI. There were variations among children living in low land (29.3%) and in medium land (21.4%). In multivariate analysis, low monthly income (AOR = adjusted odds ratio) 2.98; 95% CI (confidence interval): 1.85-7.85), illiterate family (AOR = 5.18; 95% CI: 2.92-9.17); unclean face (AOR = 18.68; 95% CI: 1.98-175.55); access to water source (AOR = 2.01; 95% CI: 1.27-3.15); less than 20 liters of water use (AOR = 4.88; 95% CI: 1.51-15.78); not using soap for face washing (AOR = 5.84; 95% CI: 1.98-17.19); not using latrine frequently (AOR = 1.75; 95% CI: 0.01-0.42); density of flies (AOR = 3.77; 95% CI: 2.26-6.29); less knowledgeable family (AOR = 3.91; 95% CI: 2.40-6.38) and average monthly income (AOR = 2.98; 95% CI: 1.85-7.85) were found independently associated with trachoma.

Conclusion

Active trachoma is a major public problem among 1–9 years children and significantly associated with a number of risky factors. Improvement in awareness of facial hygiene, environmental conditions, mass antibiotic distribution and health education on trachoma transmission and prevention should be strengthened in the District.

Trachoma prevalence in women living in rural northern India: rapid assessment findings

PURPOSE

Rapid assessment of cicatricial trachoma in adult females aged over 15 years in a previously hyperendemic rural area in Haryana, North India.

METHODS

Ten disadvantaged villages each with a population of 3000-5000 were chosen by cluster random sampling. One thousand females, 500 between 15-30 years and the rest over 30 years in the underdeveloped parts of the villages, identified by observation and consultation, were examined for signs of trachomatous scarring (TS), trachomatous trichiasis (TT) and trachomatous corneal opacity (TCO). Examinations of both eyes were performed with the aid of a binocular loupe (2.5x magnification) for signs of trachoma, its complications and other ocular morbidities.

RESULTS

Bilateral examination was carried out in all participants. About two-thirds (n = 650; 65%) of subjects did not have any signs of trachoma. The percentages of trachoma stages TS, TT and TCO were found to be 26.4%, 5.4% and 3.2% respectively. Trichiasis was observed in 54 subjects, all in the age group >30 years, and highest in the age group 66-75 years (22.8%). Females in the age group >30 years had significantly higher cicatricial trachoma compared to females <30 years (p < 0.001). Overall 59.3% of affected females had not received any treatment. Epilation and entropion surgery had been performed in 30.3% and 10.4% of affected females, respectively.

CONCLUSION

The results of our rapid assessment suggest that the presence of cicatricial trachoma remains an important health issue in females over 15 years of age.

Prevalence of trachoma in unity state, South Sudan: results from a large-scale population-based survey and potential implications for further surveys

BACKGROUND

Large parts of South Sudan are thought to be trachoma-endemic but baseline data are limited. This study aimed to estimate prevalence for planning trachoma interventions in Unity State, to identify risk factors and to investigate the effect of different sampling approaches on study conclusions.

METHODS AND FINDINGS

The survey area was defined as one domain of eight counties in Unity State. Across the area, 40 clusters (villages) were randomly selected proportional to the county population size in a population-based prevalence survey. The simplified grading scheme was used to classify clinical signs of trachoma. The unadjusted prevalence of trachoma inflammation-follicular (TF) in children aged 1-9 years was 70.5% (95% CI: 68.6-72.3). After adjusting for age, sex, county and clustering of cases at household and village level the prevalence was 71.0% (95% CI: 69.9-72.1). The prevalence of trachomatous trichiasis (TT) in adults was 15.1% (95% CI: 13.4-17.0) and 13.5% (95% CI: 12.0-15.1) before and after adjustment, respectively. We estimate that 700,000 people (the entire population of Unity State) require antibiotic treatment and approximately 54,178 people require TT surgery. Risk factor analyses confirmed child-level associations with TF and highlighted that older adults living in poverty are at higher risk of TT. Conditional simulations, testing the alternatives of sampling 20 or 60 villages over the same area, indicated that sampling of only 20 villages would have provided an acceptable level of precision for state-level prevalence estimation to inform intervention decisions in this hyperendemic setting.

CONCLUSION

Trachoma poses an enormous burden on the population of Unity State. Comprehensive control is urgently required to avoid preventable blindness and should be initiated across the state now. In other parts of South Sudan suspected to be highly trachoma endemic, counties should be combined into larger survey areas to generate the baseline data required to initiate interventions.

Oman's progress towards reaching "Ultimate Intervention Goals" for the surgery "S" component of SAFE strategy for the elimination of blinding trachoma in 2008

BACKGROUND

A community based survey for Trachomatous Trichiasis (TT) was conducted in the high (TT >5% in 1997) and meso endemic areas (TT 1% to 5% in 1997) of Oman during 2008-09.

METHODS

Investigators examined Omanis 40 age years and older from randomly selected villages. Eyes were examined for TT and vision. The medical history of surgery and advice given for TT surgery were recorded. The TT cases that were unadvised by health staff were defined as un-approached cases. Cluster adjusted prevalence of TT and risk of TT by gender were estimated.

RESULT

We examined 4,951 of 5,268 persons in high-endemic areas and 965 of 993 (97.2%) persons in meso-endemic areas. The cluster adjusted prevalence of TT in the high and meso endemic areas were 7.54% (95% Confidence Interval [CI] 6.78-8.30) and 1.69% (95% CI 0.88-2.50) respectively. There were 5 TT patients in high endemic areas and none in meso-endemic areas who were not approached or managed in the past. The prevalence of TT across all ages was less than 1 per 1,000 of the population in all wilayats of Oman. Females had a significantly higher risk of cluster adjusted TT compared to males (Odds Ratio = 1.87 [95% CI 1.85-1.89]). The prevalence of blindness was 0.5% among TT cases in high endemic areas.

CONCLUSION

Oman seems to have reached the Ultimate Intervention Goals (UIGs) of the "S" (Surgery) component in 2008 in high and meso-endemic areas. The efforts of existing eye services could be better evaluated if un-approached TT cases are used to calculate the TT prevalence. Oman needs to focus more on females with TT to reach the UIGs.

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.

Barriers to Acceptance of Intervention among Patients with Trachomatous Trichiasis or Entropion Presenting to a Teaching Hospital

PURPOSE

To determine the barriers to therapeutic intervention in patients with trachomatous trichiasis or entropion.

METHODS

Prospective study over one year in 60 patients with trachomatous trichiasis or entropion presenting to a teaching hospital. The outcome measure was reported barriers to uptake of intervention using a questionnaire. The data were analysed using chi-square and Fisher's exact tests. Patient characteristics were correlated with barriers using univariate and multivariate analysis.

RESULTS

The major barriers (operative in > 60% of patients) were illiteracy (66.7%), ignorance regarding treatment (65.0%), and fear of surgery (63.3%). Duration of symptoms in 43 females and 17 males ranged from 0.5 to 240 months (mean 30.2 +/- 45.82). Females reported significantly more barriers (average 5.8 +/- 1.88) than males (average 4.6 +/- 1.97; p = 0.03). Shorter duration was significantly related to perceived expense (p = 0.008). Patients aged =55 years more often cited young children as a barrier (p = 0.02).

CONCLUSIONS

Encouraging patients who have undergone intervention to share their experiences with community members, providing intervention in patients' villages, community involvement with patients who live alone and making gender-sensitive medical programmes might be useful in reducing the fear of surgery and enhancing awareness and uptake of intervention. Future studies must identify barriers in their regions so that attempts can be directed to overcoming them so as to reduce the blinding and non-blinding burden of trachoma.

Risk factors for trachomatous trichiasis in children: cross-sectional household surveys in Southern Sudan

We have previously documented blinding trachoma to be a serious public health problem in Southern Sudan, with an unusually high prevalence of trachomatous trichiasis (TT) among children. We aimed to investigate risk factors for TT in children in Southern Sudan. Cross-sectional surveys were undertaken in 11 districts between 2001 and 2006, and eligible participants were examined for trachoma signs. Risk factors were assessed through interviews and observations. Using logistic regression, associations between TT in children and potential risk factors were investigated. In total, 11155 children aged 1-14 years from 3950 households were included in the analysis. Overall prevalence of TT was 1.5% (95% CI 1.1-2.1). Factors independently associated with increased odds of TT in children aged 1-14 years were: increasing age (P(trend)<0.001); female gender (odds ratio=1.5; 95% CI 1.1-2.1); increasing proportion of children in the household with trachomatous inflammation-intense (TI) (P(trend)=0.002); and increasing number of adults in the household with TT (P(trend)<0.001). Our study revealed risk factors for TT in children consistent with those previously reported for TT in adults. While the associations of TT in children with TI in siblings and TT in adult relatives merit further investigation, there is an urgent need for trachoma prevention interventions and trichiasis surgery services that are tailored to cater for young children in Southern Sudan.

Human leukocyte antigen (HLA)-B, DRB1, and DQB1 allotypes associated with disease and protection of trachoma endemic villagers

PURPOSE

Trachoma remains the leading preventable infectious cause of blindness in developing countries. Human leukocyte antigen (HLA) associations with ocular disease severity and persistent Chlamydia trachomatis infection of Tanzanians living in trachoma-endemic villages were examined to determine possible protective candidate allotypes for vaccine development.

METHODS

Buccal swab scrapes were taken from subjects in the Trichiasis Study Group (TSG), which studied females only, and the Family Trachoma Study (FTS), which compared persistently infected probands who had severe disease with disease-free siblings and parents. DNA was purified for polymerase chain reaction sequence-specific oligonucleotide identification of HLA-DRB1, DQB1, and B allotypes. Infection was detected from conjunctival scrapes using a C. trachomatis-specific PCR-enzyme immunoassay for the MOMP-1 gene.

RESULTS

In the TSG, DR*B11 (odds ratio [OR], 0.48; 95% confidence interval [CI], 0.26-0.90; P=0.02) was significantly associated with lack of trichiasis, whereas HLA-B*07 (OR, 3.26; 95% CI, 1.42-7.49; P=0.004) and HLA-B*08 (OR, 5.12; 95% CI, 1.74-15.05; P=0.001) were associated with trichiasis. In addition, HLA-B*14 was significantly associated with inflammatory trachoma + follicular trachoma (OR, 3.76; 95% CI, 1.70-8.33; P=0.04). There were no significant allele frequencies for the FTS.

CONCLUSIONS

The data suggest that HLA-DRB*11 may offer protection from trichiasis in trachoma hyperendemic villages. Complete allotype identification and designation of its respective protective CD4(+) T-cell antigens could provide a testable candidate vaccine for blindness prevention. Additionally, buccal swab DNA was sufficiently stable when acquired under harsh field conditions and stored long term in the freezer for low-resolution HLA typing.

Trachoma

Trachoma is a keratoconjunctivitis caused by ocular infection with Chlamydia trachomatis. Repeated or persistent episodes lead to increasingly severe inflammation that can progress to scarring of the upper tarsal conjunctiva. Trichiasis develops when scarring distorts the upper eyelid sufficiently to cause one or more lashes to abrade the cornea, scarring it in turn and causing blindness. Active trachoma affects an estimated 84 million people; another 7.6 million have end-stage disease, of which about 1.3 million are blind. Trachoma should stand on the brink of extinction thanks to a 1998 initiative launched by WHO--the Global Elimination of Trachoma by 2020. This programme advocates control of trachoma at the community level with four inter-related population-health initiatives that form the SAFE strategy: surgery for trichiasis, antibiotics for active trachoma, facial cleanliness, and environmental improvement. Evidence supports the effectiveness of this approach, and if current world efforts continue, blinding trachoma will indeed be eliminated by 2020.

Interventions for trachoma trichiasis

BACKGROUND

Trachoma is a leading cause of avoidable blindness. The World Health Organization recommends eliminating trachoma blindness by the SAFE strategy incorporating Surgery, Antibiotic treatment, Facial cleanliness and Environmental hygiene.

OBJECTIVES

This review examined the evidence for the effectiveness of different interventions for trachoma trichiasis.

SEARCH STRATEGY

We identified trials from the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (2005, Issue 3), MEDLINE (1966 to September 2005) PubMed (searched on 21-09-06; last 90 days), EMBASE (1980 to September 2005), LILACS (March 2004) and the reference lists of included studies. We also contacted authors for details of other relevant studies.

SELECTION CRITERIA

We included randomised trials of any intervention intended to treat trachoma trichiasis and trials comparing different methods of delivering the same intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials. We contacted trial authors for missing data when necessary.

MAIN RESULTS

Seven studies met the inclusion criteria. Three studies compared different surgical interventions. These trials suggest the most effective surgery is full-thickness incision of the tarsal plate and rotation of the terminal tarsal strip 180 degrees. One study showed that bilamellar rotation was more effective than unilamellar rotation but the other two studies did not. One trial found double-sided sticking plaster more effective than epilation for the immediate management of trichiasis but required frequent replacement (odds ratio (OR) 0.01, 95% confidence interval (CI) 0.00 to 0.22). Another trial found community-based surgery increased convenience for patients without increasing the risk of complications or recurrence when compared to health centres. One trial found no difference between trichiasis surgery performed by ophthalmologists and integrated eye workers (OR 1.32, 95% CI 0.83 to 2.11). A trial comparing trichiasis surgery with and without concurrent administration of azithromycin found no difference in success rates at one year (OR 0.99, 95% CI 0.67 to 1.46).

AUTHORS' CONCLUSIONS

No trials show interventions for trichiasis prevent blindness. Certain interventions have been shown to be more effective at eliminating trichiasis. Full thickness incision of the tarsal plate and rotation of the lash-bearing lid margin through 180 degrees is probably the best technique and is preferably delivered in the community. The use of double-sided sticking plaster is more effective than epilation as a temporary measure. Surgery may be carried out by an ophthalmologist or a trained ophthalmic assistant. The addition of azithromycin treatment at the time of surgery does not appear to improve outcomes.

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.

The effect of antibiotic treatment on active trachoma and ocular Chlamydia trachomatis infection

Antibiotics are one of four arms of the SAFE strategy for the control of trachoma, an eye infection that is responsible for more cases of blindness than any condition other than cataract. The evidence for the use of topical tetracycline and oral tetracycline, doxycycline, erythromycin, cotrimoxazole and azithromycin in trachoma are reviewed here and a number of issues are nominated as research and policy priorities.

Trachoma: new assault on an ancient disease

Trachoma is the leading infectious cause of blindness worldwide. The World Health Organization (WHO) estimated that approximately 5.9 million persons are blind or have severe vision-loss as a result of trachoma, and another 10 million are at high risk. Trachoma preferentially affects the most deprived communities, and within these communities, women and children bear the brunt of the burden. In recent years, there has been a renewed focus on research and heightened enthusiasm for strengthening trachoma control programs in afflicted countries. WHO has convened an alliance of member countries, non-governmental organizations, and other partners for the Global Elimination of Blinding Trachoma by the year 2020, and endorsed the multi-faceted SAFE strategy for trachoma control. SAFE-Surgery, Antibiotics, Face-washing, and Environmental improvement-has incorporated sound research on elements likely to reduce trachoma, and trachomatis blindness, in endemic communities. This review summarizes current knowledge about trachoma and its causative agent, Chlamydia trachomatis, the epidemiology and risk factors for trachoma as a prelude to reviewing the SAFE strategy. While ongoing research to support the knowledge base for SAFE must continue to be a priority, the full implementation of SAFE is the best hope for countries to reduce the global burden of blindness from this preventable cause.

Immunopathogenesis of chlamydia trachomatis infections in women

OBJECTIVE

To develop a model of pathogenesis by which Chlamydia trachomatis progresses from acute to chronic infection, and finally serious disease (salpingitis, tubal occlusion).

DESIGN

Review of current literature located through web-based Medline searches using key words: Chlamydia trachomatis, immunology, cytokines, heat shock protein, infertility.

RESULT(S)

Cell-mediated immune mechanisms appear to be critical in determining whether acute infection is resolved or progresses into chronicity with pathological outcome. What determines the particular immune pathway depends on a range of determinants-HLA subtype and human genetics, cytokine profile, infectious load, route of infection, and endocrinology. A clearer picture of the natural history of chlamydial pathology may assist in providing better predictors of those women who may go on to develop significant sequelae after infection.

CONCLUSION(S)

Predicting those who may develop serious disease, including infertility, may contribute to improved management of such persons during earlier stages of infection and assist in prevention.

Resource allocation to prevent trachomatous low vision among older individuals in rural areas of less developed countries

Trachomatous low vision can be prevented by treating or preventing infection or through surgery to treat trichiasis. Resource allocation to prevent trachomatous low vision should be directed to those interventions that are the most cost-effective. In order to assess which of many potential interventions are the more cost-effective, data on the epidemiology of the disease, the effectiveness of community- and facility-based interventions, and the cost of the interventions are required. This paper provides a stylized model of the path from risk of infection through disease to trachomatous low vision or blindness that delineates the points at which interventions may occur and for which data are required. The literature reveals a considerable amount of data regarding the epidemiology of the trachoma and its sequelae but little on the effectiveness of community-based interventions and only one study that measured costs directly. More data are needed to assist policy makers and international program partners who seek to make efficient resource allocation decisions in an effort to eliminate trachoma as a cause of incident blindness in the developing countries in which trachomatous blindness remains prevalent.

Rapid assessment of trachoma prevalence--Singida, Tanzania. A study to compare assessment methods

This article presents a methodology for the rapid assessment of trachoma that was validated against a prevalence survey, undertaken simultaneously in the same 12 villages in central Tanzania. The rapid assessment protocol suggests examinations for active trachoma in 50 children ages 1-10 in at least 20 households chosen from the high-risk neighborhoods in each village. Women over the age of 15 in the same households were examined for trichiasis. In the rapid assessment, 244 households were visited, with 691 children and 470 women examined. In the prevalence survey, 377 households were visited, with 1855 children and 1310 women examined. Rankings of the villages using population prevalence of active disease and rapid assessment prevalence of active disease are highly correlated (Spearman correlation = 0.59, p < 0.05). In fact, the three villages with the highest prevalence in the population data were identified as the villages with the highest prevalence by the rapid assessment. Although rankings of the villages using population prevalence of trichiasis and rapid assessment prevalence of trichiasis are positively correlated, this correlation is not significantly different from zero, the village with the highest trichiasis prevalence according to the random sample being ranked as 8th by the rapid assessment. The cost of the rapid assessment was roughly one-third the cost of the prevalence survey. Thus, it appears that the rapid assessment method can quickly and inexpensively determine which villages have the greatest amount of active disease in children, and roughly estimate the burden of trichiasis in the community.

OmpA genotypic evidence for persistent ocular Chlamydia trachomatis infection in Tanzanian village women

BACKGROUND

Trachoma is still a significant problem in the developing world. Adult women are at higher risk of developing scarring and trichiasis, the potentially blinding sequelae, compared to men. In part, the higher risk may be due to more frequent infections in women because of their frequent contact with children, the main reservoir of C. trachomatis infection. However, other factors associated with infection, particularly constant infection, in adult women need to be identified.

METHODS

A group of 118 women who were infected with C. trachomatis and 118 women who were not infected, but of similar age and trachoma status, were identified in 1996 from a population-based sample of women age 16 and older from eleven villages in Kongwa, Tanzania. This group of 236 was re-contacted three years later to ascertain trachoma status and determine infection status using polymerase chain reaction-enzyme immunoassay (PCR-EIA). Positive samples at both time points were examined for serovar and genotype shift, using ompA sequencing information.

RESULTS

Of the original 236 women, 165 (70%) completed exams in 1999. Fifty-eight (35%) of the 165 women were excluded from this analysis because they received antibiotic treatment for trachoma in the six months prior to the second exam. Infection at baseline was the most important predictor of infection three years later (Age-adjusted odds ratio (95% confidence interval) 6.6 (1.8-24.4)). A total of 17 women (16%) were infected at the two examinations, and of the 15 for whom genotyping could be done, 11 (73%) were infected with the same ompA genotype at both time points. Chronically infected women were more likely to have trichiasis, scarring, and active trachoma at baseline than those never infected or infected only once. Only 41% of the chronically infected women were living in houses with infected pre-school children, but 24% were in houses with no children. Four of ten women with trichiasis developed incident corneal opacity over the three years.

CONCLUSIONS

The data provide evidence for persistence of infection in a sub-group of women. The strongest predictor of infection at follow-up was baseline infection, and most were infected with the same genotype at both time points. For women with persistent infection, at least half were either not living with children or not living with infected children, suggesting that continual re-exposure from a close family member was less likely. Chronic infection is likely related to both exposure and immunological factors, and these need to be further identified. Inclusion of women in community-based treatment programs, regardless of whether a child is present in the house, is likely to be important in preventing the progression of inflammatory trachoma and scarring to trichiasis.

Evaluation of barriers to surgical compliance in the treatment of trichiasis

PURPOSE

Eyelid repair surgery can prevent the effects of trichiasis leading to visual loss. Cost, transportation difficulties, and familial responsibilities have been identified as major barriers to surgical compliance. We evaluated whether offering trichiasis surgery in the village was effective in increasing the rate of surgical acceptance and in decreasing perceived barriers to surgery.

METHODS

In 1989, 205 women with trichiasis were identified in Central Tanzania and were offered free surgery along with free transport. As of 1991, only 18% of these women had undergone the surgery. We followed-up these women 7 years later after village level surgery was introduced.

RESULTS

Since 1991, an additional 12% of the women had undergone eyelid surgery. 44% were conducted in the village. Surgical cases since 1991 reported shorter travel times to the place of surgery, similar post-surgical problems, and fewer days in the hospital. While providing benefits to the patient, increased village eye services did not increase the rate of surgical acceptance. The women who declined surgery did not know surgery in the village was available and the perceived cost and transportation difficulties continued to be barriers. 50% of the non-acceptors stated that there was nothing that would enable them to accept surgical intervention despite the fact that 3/4 of them reported eye symptoms that interfered with their daily activities.

CONCLUSIONS

The cost efficacy of village level eye services needs to be evaluated and the awareness of these services increased.

Evidence of genetic susceptibility to Chlamydia trachomatis-induced pelvic inflammatory disease in the pig-tailed macaque

The macaque model of chlamydial pelvic inflammatory disease (PID) demonstrates individual variability in the time of onset of intrapelvic adhesions. Some animals develop adhesions rapidly, within 2 weeks after a single tubal inoculation with Chlamydia trachomatis, while in others, adhesions are not observed until 2 weeks after a second tubal inoculation. To test whether this variability correlates with major histocompatibility complex (MHC) class I haplotype, we used macaque alloantisera and mouse anti-HLA monoclonal antibodies to determine the MHC class I haplotypes of 44 C. trachomatis-infected macaques (Macaca nemestrina). Macaques developing gross tubal adhesions after the first chlamydial inoculation were classified as susceptible (n = 29), while those not developing adhesions until after the second chlamydial inoculation were classified as relatively resistant (n = 15), to adhesion formation. Three antibody specificities correlated with susceptibility (odds ratio [OR] 5.2, P < 0.01; OR 6.1 and 4.3, P < 0.05), and two correlated with relative resistance to adhesions (OR 0.1, P < 0.05; OR 0.2, P < 0.01). Because several of these antibodies are cross-reactive, as many as five different MHC class I alleles (three increasing and two decreasing ORs) or as few as two different MHC class I alleles (one increasing and one decreasing OR) could be correlated with risk of adhesion formation. We conclude that in macaques, susceptibility or relative resistance to rapid formation of tubal adhesions is correlated with expression of MHC class I alleles, consistent with reports of MHC class I restriction of chlamydial immunopathology in humans.

Visual acuity in an Australian aboriginal population

BACKGROUND

Australia is a developed country. However, Aboriginal Australians have rates of blindness comparable to Third World countries. There have been well-funded eye health programs for 15 years in Central Australia. This paper examines if there has been an improvement in visual disability of one traditional group of Aboriginal Australians.

METHODS

Results from an eye health survey of the Anangu Pitjantjatjara of South Australia in 1990 are presented. These data are compared with results for 'blindness' and 'poor vision' from a national survey undertaken in 1976. The two surveys were comparable in design, both were cross-sectional population-based prevalence surveys. Prevalence rates were adjusted for the size of the source population.

RESULTS

Young rural Aboriginal Australians have good visual acuity. Low vision and blindness (WHO definitions) occur in 19.6% and 10.4% of 60+ year olds, respectively. Women were more likely than men to be blind or have low vision (OR = 1.93; 1.06-3.58). There was a decline in 'poor vision' between surveys (OR = 2.86; 1.86-4.75) but not in 'blindness'.

CONCLUSION

Although there has been a reduction in the prevalence of visual disability in rural Aboriginal Australians, improvements in the provision of eye care for the elderly need to occur.

The epidemiology of trachoma in rural Kenya. Variation in prevalence with lifestyle and environment. Study Survey Group

PURPOSE

Ocular examination surveys were carried out in Kenya by the International Eye Foundation as a component of the Kenya Rural Blindness Prevention Project to determine the national prevalence of blindness and ocular morbidity and major causes. A goal of the surveys was to determine the overall geographic distribution and severity of trachoma throughout Kenya.

METHODS

Using a random cluster household sampling technique, 13,803 people of all ages and of diverse cultural and ethnic backgrounds were identified in eight regions of Kenya. A detailed examination for active and inactive trachoma was carried out on each person surveyed as part of the general ocular examination.

RESULTS

The prevalence rate of visual loss (< 20/60) due to trachoma in the better eye was 7.2/1000. Active trachoma was present in 19% of all persons examined, and 50% of all those with trachoma were found to have moderate to severe inflammation. Prevalence varied according to survey region from less than 1% in four regions where agriculture is the economic base, to 57% and 63% in two arid pastoral regions. Trachoma prevalence varied from 28% in children younger than 3 years of age to 11% in persons older than 60 years of age. Potentially blinding eyelid deformities secondary to chronic trachoma occurred in 5.0% of the rural population, and 1.2% of the rural population displayed associated corneal scarring. Lid scarring, corneal scarring, and lid deformities were greater in prevalence among females of all age groups when compared with males.

CONCLUSIONS

Trachoma prevalence in Kenya varies widely from region to region. High prevalence is associated with high climatic aridity, and lower prevalence is associated with areas of greater rainfall, sustainable agriculture, and a higher general standard of living. Within high-risk regions, there are wide variations in age-specific prevalence and severity of the disease. Potentially blinding sequelae of trachoma are more prevalent in females than in males.

The global burden of trachomatous visual impairment: II. Assessing burden

This paper builds on results of a previous paper on the prevalence of trachomatous visual impairment as the foundation for assessing the global burden of trachomatous blindness and low vision: approximately 2.9 million cases of trachomatous blindness and 3.8 million low visioned corresponding to a global prevalence of trachomatous visual impairment equal to 1.3/1,000 in 1990 was estimated. For each visually impaired person, the years of life lost due to premature mortality and the years lived in a handicapped state are added to yield a single measure of disease burden called handicap adjusted life years (HALYs). Age, gender and visual acuity group specific HALYs are multiplied by the prevalence of trachomatous visual impairment to yield an estimate of the global burden of trachoma visual impairment equal to 80 million HALYs. Analysis of the distribution of the global burden by age, gender, visual acuity and region provide direction for trachoma research and programme priorities. Sensitivity analysis reveals that the burden estimates of trachomatous visual impairment may vary from as low as 15 million to as high as 500 million HALYs. Given this degree of variability, burden comparisons with other blinding and non-blinding conditions for the purposes of identifying health sector priorities may be misleading.

Predicting surgical compliance in a cohort of women with trichiasis

Trichiasis/Entropion are the severe consequences of chronic trachoma during early life. Blindness and vision loss is preventable with timely lid surgery to correct trichiasis. In a trachoma hyperendemic region of Central Tanzania, a two year follow-up survey was conducted among 205 women with trichiasis to determine the proportion who had had surgery and the barriers to having surgery. Only 18% of the women had undergone surgery by the 2 year follow-up. Those who had surgery tended to report more eye problems at baseline and have more corneal opacities at baseline. Barriers preventing women from going to surgery were costs, problem of children left at home alone, and difficulties in identifying someone to accompany them to the health center. Over 2/3 of those who had surgery reported a significant decrease in pain, improvement of vision, and improved ability to carry out activities of daily life. Ways to improve compliance with recommendations for trichiasis surgery need to be developed.