Risk Of Trachoma Research Articles

Prevalence of Trachoma-Related Trichiasis and Corneal Opacity in Rural Myanmar: The Meiktila Eye Study

To describe the prevalence of trachomatous trichiasis and corneal opacity (CO) within central Myanmar. Population-based cross-sectional ophthalmic survey. Random, stratified, cluster sampling of the inhabitants > or =40 years of age from villages in the Meiktila District was performed; 2481 eligible participants were identified and 2076 participated in the study. Visual acuity was measured using an E Snellen chart at 6 meters. Lid, ocular surface, and anterior segment examinations were performed at the slit lamp. Trachoma was graded as trachomatous trichiasis (TT) or CO according to the World Health Organization grading system. The population prevalence of trachoma (TT and CO) was 2.6% (95% confidence interval [CI]. 1.67%-3.42%). For every 1-year increase in age, the odds of trachoma increased by 5.3% (95% CI, 4.9%-5.7%). There was no significant effect of gender on the prevalence of trachoma (P = 0.5). No formal schooling was a strong predictor of trachoma (odds ratio, [OR], 4.9; 95% CI, 3.9-6.1), and having <3 children in the house was protective (OR, 0.75; 95% CI, 0.61-0.93); however, neither occupation nor the number of people in a household had an effect on trachoma. The prevalence of blinding trachoma in central Myanmar remains relatively low. This is a tribute to the success of the Burma Trachoma Control Program and demonstrates the need for such a program to remain an integral part of public health care and community health services to further diminish the prevalence of this condition. This will be facilitated by a focus on trachoma risk factors and further research into the prevalence of inflammatory trachoma within the pediatric population.

The relationship between prevalence of active trachoma, water availability and its use in a Tanzanian village

This study aimed to establish the relationship between the prevalence of active trachoma in children, water availability and household water use in a village in Tanzania. Nine hundred and fourteen children aged 1-9 years were examined for signs of trachoma. Data were collected on time taken to collect water, amount of water collected and other trachoma risk factors. In a sub-study, 99 randomly selected households were visited twice daily on two consecutive days to document patterns of water use. The prevalence of active trachoma in the children examined was 18.4% (95% CI 15.9-20.9). Active trachoma prevalence increased with increasing water collection time (OR 2.25; 95% CI 1.13-4.46) but was unrelated to the amount of water collected. In the sub-study, active trachoma prevalence was substantially lower in children from households where more water was used for personal hygiene (P for trend < or =0.01), independent of the total amount of water used. The allocation of water to hygiene was predicted by lower water collection time. The key element in the relationship between water availability and trachoma is the allocation of water within households. Collection time may influence both the quantity of water collected and its allocation within the household.

Rapid assessment for prioritisation of trachoma control at community level in one district of the Kaolack Region, Senegal

The objective of this study was to use a modified Lot Quality Assurance Sampling methodology to classify communities according to prevalence of active trachoma and to estimate the prevalence of trachoma and trichiasis in Nioro department, Kaolack Region, Senegal. A survey was conducted using two-stage cluster sampling to select 50 children aged 2-5 years in each of 33 clusters. In total 1,648 children were examined for active trachoma. Information on trachoma risk factors was collected through interviews with the mother or the household head of the child. Adults (>40 years) with trichiasis were identified through case finding. Nineteen clusters had a low prevalence of active trachoma in children aged 2-5 years (<20%), 11 had medium prevalence (20-40%) and three had high prevalence (>40%). The prevalence of active trachoma in children aged 2-5 years was 17.4% (95% CI 12.9-21.8%). Multivariate-adjusted predictors of active trachoma were: age, facial cleanliness, hygiene practices and keeping cattle in the household. The prevalence of trichiasis in adults aged over 40 years was 1.77% (95% CI 1.24-2.51), equating to 985 adults (95% CI 765-1250) with trichiasis in Nioro department. In conclusion, a survey using rapid methodology showed that trachoma is a problem of public significance in Nioro department, Senegal.

Contribution of Sex-linked Biology and Gender Roles to Disparities with Trachoma1

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.

Modeling the economic net benefit of a potential vaccination program against ocular infection with Chlamydia trachomatis

Trachoma is an ocular infection caused by Chlamydia trachomatis that carries a huge public health burden as a leading cause of preventable blindness globally. We developed a model of the economic benefits of a potential vaccine. Factors that impact the efficacy of a vaccination program (such as the sensitivity and specificity of algorithms to identify high-risk individuals), and personal and environmental risk factors for trachoma affect the maximum vaccination and screening costs at which a vaccination program can achieve a positive net benefit. This model is useful for planning vaccine programs in areas with varying trachoma risk factors and endemicity.

Household willingness to pay for azithromycin treatment for trachoma control in the United Republic of Tanzania.

Household willingness to pay for treatment provides important information for programme planning. We tested for relationships between socioeconomic status, risk of trachoma, perceptions of the effects of azithromycin, and the household willingness to pay for future mass treatment with azithromycin. We surveyed 394 households in 6 villages located in central United Republic of Tanzania regarding their willingness to pay for future azithromycin treatment. A random sample of households with children under 8 years of age was selected and interviewed following an initial treatment programme in each village. Data were gathered on risk factors for trachoma, socioeconomic status, and the perceived effect of the initial azithromycin treatment. Ordered probit regression analysis was used to test for statistically significant relationships. 38% of responding households stated that they would not be willing to pay anything for future azithromycin treatment, although they would be willing to participate in the treatment. A proxy for cash availability was positively associated with household willingness to pay for future antibiotic treatment. Cattle ownership (a risk factor) and being a household headed by a female not in a polygamous marriage (lower socioeconomic status) were associated with a lower willingness to pay for future treatment. A perceived benefit from the initial treatment was marginally associated with a willingness to pay a higher amount. As those at greatest risk of active trachoma indicated the lowest willingness to pay, imposing a cost recovery fee for azithromycin treatment would likely reduce coverage and could prevent control of the disease at the community level.

Trachoma, flies and environmental factors in Burkina Faso

The presence of flies is one of the earliest risk factors for trachoma and it has been suggested that flies could act as vectors for transmission of chlamydiae. A national trachoma survey was conducted in 1997 in Burkina Faso to (i) study the relationship between trachoma occurrence, flies, dirty faces and some environmental factors, and (ii) investigate the role of flies in the presence of trachoma. The country was stratified into eight groups of provinces and a random sample of 30 clusters was selected in each group. All children aged < 10 years were examined for the diagnosis of active trachoma (trachomatous inflammation which was follicular and/or intense) and the dirtiness of the face and the presence of flies on the face were recorded. The children's carers were questioned about the number of baths given and daily face-washing. Household heads were asked about ownership of cattle and small ruminants. The presence of latrines, a stable, and garbage collection inside the yard was noted. Among 16 514 children examined, 27.0% had active trachoma and 3.3% intense inflammatory trachoma. Flies were present on 11.2% of children's faces and 82.4% and 19.7% of these children had active and intense inflammatory trachoma, respectively. Among the 30.2% of children with dirty faces, 70.2% had active and 10.2% intense inflammatory trachoma. In multivariate analysis, at least one daily bath showed a protective effect on both active and intense inflammatory trachoma. Face-washing twice daily was found to be significantly protective for active trachoma in some regions. A strong association was demonstrated between the presence of flies and dirty faces (odds ratio = 334, 95% confidence interval 202–546). The presence of flies on children's faces, dirty faces and trachoma appeared to be strongly associated. Although the presence of flies may be a marker of socio-economic status and is probably linked with other trachoma risk factors, our data indicated that interventions targeting fly control should be an important issue in controlling trachoma.

Trial of Trachoma Rapid Assessment in a subdistrict of northern Nigeria

PURPOSE. To assess the usefulness of Trachoma Rapid Assessment (RA) in priority ranking of trachoma areas. METHODS. RA was conducted concurrently with a cross-sectional trachoma prevalence survey in some villages selected from the communities at risk for trachoma in the Kaita Local Government Area of northern Nigeria. The RA team consisted of two ophthalmic nurses. Pen torches and loupes were used for the examination. Data were collected on the seven components of the RA ‘information pyramid’ for all the selected villages. The data were analyzed using the RA methodology guidelines to determine the priority villages for trachoma intervention. This was compared with the ranking from the cross-sectional trachoma prevalence survey. RESULTS. The results of RA were found to be in agreement with the cross-sectional survey in 53.3% of the villages in the priority ranking of trichiasis, while in the priority ranking of active trachoma the agreement between the two methods was found to be 60%. The risk factors for trachoma were shown to be of high magnitude in all the villages using both the RA method and the prevalence survey. CONCLUSION. RA may be a more useful tool when applied to a vast area where the risk of trachoma is likely to differ greatly between different parts of the area. In the determination of the trichiasis pattern of a community by RA, it may be more useful to use the actual number of trichiasis cases in the area rather than the prevalence of trichiasis. The operational definition of some risk factor indicators seems very subjective and vague. The RA method needs more validation to sharpen the indicators used.

RE: "RISK FACTORS FOR CONSTANT, SEVERE TRACHOMA AMONG PRESCHOOL CHILDREN IN KONGWA, TANZANIA"

We read the recent article by West et al. with much enthusiasm and congratulate them on their many contributions to the field of trachoma prevention. In response we were concerned that a few issues concerning trachoma prevention may not have been clear to or subject to misinterpretation by the readers of the American Journal of Epidemiology who may not be familiar specifically with this field. In 1989 Taylor et al. reported that children with unclean faces appeared to be at a higher risk of trachoma. Their finding was further supported by the work of West et al. who noted that the odds of having trachoma increased if a childs face had both nasal discharge and flies on it. In fact the beneficial effects of personal and environmental sanitation have been well recognized and documented in numerous publications. Successful trachoma eradication programs based solely on improving personal hygiene have been described almost 50 years ago and successfully implemented in many parts of the world. However the optimal approach to mass antibiotic therapy has been a topic of intensive epidemiologic investigation for many years and requires further study. Given the recognized value of face-washing as a method for reducing the risk of trachoma we would like to express our concern about the rationale of withholding this from a group of children with known risk factors for developing trachoma. The authors conclusion Improved face-washing plus antibiotic treatment may decrease the likelihood that these children will be at risk for blinding complications in adulthood is certainly valid and respected but this has been known for several decades. While epidemiologic research may not be able to cause sustained socioeconomic improvement of communities with endemic trachoma we believe these investigations should build on previous knowledge in an effort to carry out the mission of epidemiology and public health. (full text)

Prevalence and risk factors for trachoma in Sarlahi district, Nepal.

To estimate the prevalence of trachoma in preschool children in Sarlahi district, Nepal, and to identify risk factors for the disease. A stratified random sample of 40 wards was selected for participation in a trachoma survey. Within each ward, a systematic 20% sample of children 24-76 months of age was chosen to determine the presence and severity of trachoma using the World Health Organisation grading system. A total of 891 children were selected and 836 (93.8%) were examined for trachoma from December 1990 to March 1991. The prevalence of active trachoma was 23.6% (21.9% follicular and 1.7% intense inflammatory). Cicatricial trachoma was not seen in this age group. The prevalence of trachoma ranged from 0 to 50% across wards with certain communities at much higher risk for trachoma than others. Three year old children had the highest prevalence of follicular (25.5%) and intense inflammatory trachoma (4.3%). Males and females had similar prevalence rates. Wards without any tube wells were at higher risk than those with one or more tube wells. Lower rates of trachoma were seen in families who lived in cement houses, had fewer people per room, more servants, more household goods, animals, and land. Hence, less access to water, crowding and lower socioeconomic status were risk factors for trachoma. Although follicular trachoma is prevalent, intense inflammatory trachoma is relatively rare and scarring was not observed in this preschool population. Hence, this population may not be at high risk for repeat infections leading to blindness in adulthood.

Exposure to children and risk of active trachoma in Tanzanian women.

The authors surveyed the trachoma status of 515 women aged 18-60 years and 527 children aged 1-7 years in the trachoma hyperendemic region of Kongwa, Tanzania, in 1989 to further describe the importance of exposure to young children as a risk factor for active trachoma in women. The women were identified as caretakers, who currently cared for children aged 1-7 years; noncaretakers, who lived with, but did not care for, children aged 1-7; or those without children aged 1-7 in the household. The age-adjusted odds ratios for active trachoma seemed to rise with greater exposure to young children, from 1.00 for women without such children, to 1.63 for noncaretakers and 2.43 for caretakers (trend test, p = 0.08). Among those who lived in households with young children, the prevalence of active trachoma in women increased with the total number of young children cared for and with the number of infected children cared for. The prevalence of active trachoma was 40% (6 of 15) for caretakers of three or more infected children, compared with 0 (0 of 88) for caretakers with no infected children (p < 0.0001). Caring for infected children also appeared to be associated with signs of chronic trachoma in caretakers. Noncaretakers who lived with infected children were not at a significantly increased risk for trachoma compared with noncaretakers who were not exposed to such children (5.4% (three of 56) vs. 5.6% (one of 18); p > 0.4). None of the facial signs observed in the children (flies on the face, nasal discharge, etc.) appeared to increase the odds ratio of active trachoma in caretakers beyond the increase associated with trachoma alone in the child. These data support the hypothesis that active disease in women is associated with direct caretaking of young children with active disease. Strategies that interrupt household transmission may affect the binding sequelae of trachoma in women.

Trachoma and Flies

The risk of active trachoma in children appears to be higher in association with flies in the environment. However, a measure of fly density that could consistently be related to an increased risk of trachoma is unknown. In a survey of six villages in a hyperendemic area of Tanzania, a comparison was made between the number of flies on the faces (face-fly scores) of children and the number of household flies around the main doorways (household-fly scores). The risk of trachoma associated with each measure was evaluated after adjusting for the age and sex of the child. A multiple logistic regression model demonstrated that the presence of flies on the face was consistently associated with increased risk of trachoma, and that number of flies on the face is a superior predictor in terms of ease of measurement and strength of association than is number of household flies.

Facial Cleanliness and Risk of Trachoma in Families

Trachoma is the leading infectious cause of blindness worldwide, and epidemiologic studies of factors that may increase the transmission of ocular Chlamydia trachomatis are needed. In two villages in a hyperendemic area of Central Tanzania, 472 (90%) of 527 preschool-aged children were examined for specific signs of unclean faces and presence of trachoma. The odds of trachoma were 70% higher in children with flies and nasal discharge on their faces. Other facial signs were not important. In large families, the odds of trachoma increased 4.8-fold if a sibling had trachoma and 6.8-fold if a sibling had trachoma and an unclean face. Health education strategies aimed at improving face washing need to target cleaning nasal discharge and keeping flies off children's faces.

Delayed eye and other consequences from exposure to methyl isocyanate: 93% follow up of exposed and unexposed cohorts in Bhopal.

A follow up study three years after exposure to methyl isocyanate in 93% of exposed survivors and "control" residents in 10 Bhopali communities showed an excess of eye irritation, eyelid infection, cataract, and a decrease in visual acuity among the exposed people. Breathlessness was twice as common in the heavily exposed clusters as those with lower exposure, a trend that could not be explained by different age or smoking patterns (OR 2.05, 95% CI 1.36-3.08). Case referent analysis of outpatient attendances at Bhopal Eye Hospital, considering patients with severe refractive errors and astigmatism as "controls," showed a 40% increased risk of trachoma, 36% increased risk of other lid infections, and 45% increased risk of irritant symptoms among previously exposed people. "Bhopal eye syndrome" may thus include full resolution of the initial interpalpebral superficial erosion, a subsequent increased risk of eye infections, hyperresponsive phenomena (irritation, watering, and phlyctens), and possibly cataracts. It remains to be confirmed whether this reflects a more generalised disease as a consequence of previous exposure to methyl isocyanate or whether it is only the eye that is affected.

Hygiene factors and increased risk of trachoma in central Tanzania.

Trachoma remains the major infectious cause of blindness in many developing areas, especially where hygiene is poor. The practices and behaviors associated with an increased risk of trachoma were studied in central Tanzania, where a stratified random cluster sample of 8409 people was examined. Data were collected on family and individual characteristics and behaviors and on trachoma status. Overall, 60% of the children aged 1 to 7 years had active inflammatory trachoma, and 10% of those aged 60 years or older had trichiasis. Regression analysis showed that active inflammatory trachoma in children was associated with the characteristics of the more traditional families and several measures of poor personal hygiene. Two important risk factors for severe inflammatory trachoma were poor facial cleanliness in children (odds ratio of 1.7 [1.17, 2.50]) and household fly density (odds ratio of 1.63 [1.17, 2.29]). Both factors are potentially amenable to intervention. These data suggest that an intervention strategy aimed at these hygiene measures would provide an effective method of controlling trachoma in this region, and a similar approach may be useful in other areas.