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.     

Changing water-use patterns in a water-poor area: lessons for a trachoma intervention project

An epidemiological survey carried out in the Dodoma region of Tanzania found that high rates of trachoma infection in pre-school children were associated with unwashed faces. Prior to a planned trachoma intervention project, a pilot study was done on household decisions about water use and perceptions about face washing and eye disease. The study found that mothers overestimated the amount of water necessary to wash a child's face. In addition, mothers would not change their water-use priorities without the consent of their husbands and the support of the community. Therefore a health education program was designed to address the perception that face washing required a great deal of water. The program also sought to involve and re-educate the whole community rather than focus only on the mothers who were most likely to wash the children's faces.     

Water use and health in Mueda, Mozambique

A comparison of domestic water use in 2 villages in Mueda, Mozambique, indicated that a reduction in the length of the water collection journey from 5 h to 10 min was associated with an increase in average water consumption from 4.1 to 11.1 litres per person per day. Bathing and washing clothes accounted for 70% of the increased total. Bathing of children was a regular nightly event in the village with a water supply but almost unknown in the other. Water used for food preparation also increased, suggesting that scarcity of water may also influence diet. A major benefit of water supply is the saving of women's time and effort from water collection. In Mueda, it was an average of 1 3/4 h per day. More than half the time saved was spent on other household tasks, particularly grinding cereals, and on other productive work. Women spent much of the remainder with their children. A trachoma survey, organized as a training exercise for medical students, found a 19% prevalence of trachoma in the village with a water supply, while the prevalence was twice this figure in another village with no supply.     

The ecology of trachoma: an epidemiological study in southern Mexico

A total of 1097 people in two communities in Chiapas, Mexico, were examined for trachoma, and information was obtained about personal and family hygiene. Trachoma was hyperendemic; approximately 25% of those under 10 years old were found to have significant inflammatory trachoma and almost 100% of those aged over 40 years had cicatricial trachoma, although the prevalence of trachoma differed significantly between the two communities. Risk factor analysis was performed by contingency table analysis and χ² testing. The most important parameter associated with the occurrence and severity of inflammatory trachoma in children was the frequency of face washing. Children who washed their faces 7 or more times per week had significantly less trachoma than those who washed less often (χ²_2df = 28.7; P < 0.001). This effect was independent of age, use of clean water and soap, or use of clothes to dry the face. Children who washed infrequently and who used clothes to dry the face or clean the nose were more at risk for trachoma. No parameters of family hygiene or socioeconomic status correlated with the amount of trachoma in a family.     

Risk factors for trachoma in Mali

OBJECTIVES: Prior to commencing a campaign to eliminate blinding trachoma in Mali, a national disease prevalence survey was conducted from March 1996 to June 1997. The prevalence of trachoma was estimated and potential risk factors were studied. METHODS: In each of Mali's seven regions (excluding the capital Bamako), a sample of 30 clusters was taken from the general population, in accordance with the principle of probability proportional to the size of the community. All children under 10 years of age were examined. The simplified clinical coding system proposed by the World Health Organization was used. The position of each village was established and subsequently related to the nearest meteorological station. Socioeconomic and environmental information was collected at both village and household level. The mother or caretaker of each child was questioned about availability and use of water for washing the child. At the time of examination, facial cleanliness and the presence of flies on the face were noted. RESULTS: A total of 15,187 children under 10 years of age were examined. The prevalence of active trachoma (follicular [TF] or intense trachoma [TI]) was 34.9% (95% CI : 32.3-37.6) and the prevalence of TI was 4.2% (95% CI : 3.5-5.0). Aridity/environmental dryness appears to be a risk factor influencing the current geographical distribution of trachoma. Small villages had considerably higher trachoma prevalence than their larger neighbours. The proximity of a medical centre and the existence of social organizations such as a women's association were associated with lower levels of trachoma. Crowded living conditions increased the risk. Using a monetary marker of wealth, we observed a linear inverse relation between wealth and trachoma prevalence. The presence of a dirty face was strongly associated with trachoma (odds ratio [OR] = 3.67) as was the presence of flies on the child's face (OR = 3.62). Trachoma prevalence increased with distance to a water source. Disease prevalence decreased with a higher frequency of both face washing and bathing. CONCLUSIONS: Of all the risk factors examined, facial cleanliness had the strongest association with the prevalence of trachoma. This was followed by the presence of flies on the child's face. Both face washing and bathing showed beneficial effects. Socioeconomic factors such as wealth were significantly explanatory. It is likely that hygiene education and fly control by environmental improvement could have a very significant impact on the prevalence of trachoma in Mali.     

Water availability and trachoma

As part of an epidemiological survey of risk factors for trachoma in 20 villages in the United Republic of Tanzania, we investigated the relationship of village water pumps, distance to water source, and quantity of household water to the risk of inflammatory trachoma. We also evaluated whether there was an association between the cleanliness of children's faces and these water variables. No association was found between the presence of a village water supply and the prevalence of trachoma. However, the risk of trachoma in the household increased with the distance to a water source--although there was no association with the estimated daily amount of water brought into the house. Likewise, children were more likely to have unclean faces if they lived more than 30 minutes from a water source, but whether they had clean faces was not associated with the daily quantity of water brought into the household. The effect of the distance to water supply on trachoma may well reflect the value placed on water within the family, and this determines the priority for its use for hygiene purposes. The results of the study suggest that changing the access to water per se may be insufficient to alter the prevalence of trachoma without also a concomitant effort to change the perception of how water should be utilized in the home.     

Risk factors for trachoma: 6-year follow-up of children aged 1 and 2 years

The authors investigated the long-term stability of risk factors in predicting the presence of active trachoma and severe inflammatory trachoma in 176 children in Kongwa, Tanzania, who were aged 1 and 2 years in 1989 and were available for follow-up in 1995. Familial cattle ownership, living more than 2 hours away from a water source, and facial cleanliness at both time points were associated with the presence of active trachoma at both time points (odds ratio (OR) = 2.58, 95% confidence interval (CI): 1.15, 5.79; OR = 3.07, 95% CI: 1.23, 7.64; and OR = 0.52, 95% CI: 0.26, 1.03, respectively). An association of familial cattle ownership with facial cleanliness and water accessibility was observed. Having a clean face at both time points was associated with lower odds of active trachoma at both time points for children in non-cattle-herding families (OR = 0.40, 95% CI: 0.18, 0.87). Living more than 2 hours away from a water source at both time points increased the odds of active trachoma at both time points in children of cattle-herding families (OR = 8.00, 95% CI: 1.99, 32.10). Noticeably, severe inflammatory trachoma at baseline predicted mortality in children from villages in which trachoma was less common (OR = 3.75, 95% CI: 1.09, 12.98). The results suggest that risk factor reduction could diminish persistent disease.     

闵行区某外来务工人员子女学校学生沙眼患病现况

目的 了解闵行区外来务工人员子女沙眼患病情况及其影响因素,为学生沙眼防治措施提供可靠依据.方法 按世界卫生组织(1987年)诊断标准,对整群随机抽取的闵行区某外来务工人员子女学校703名在校小学生进行沙眼筛查、流行病学调查以及干预治疗.结果 闵行区外来务工人员子女沙眼患病率为9.0％;洗手习惯、洗澡频率、揉眼习惯、有无专用学习桌椅和沙眼史、父亲眼异物感或眼痛、母亲眼异物感、家长或孩子眼睛不适时是否就诊及滴眼药水的态度均与沙眼患病有关(P值均＜0.05).多因素Logistic回归分析显示,勤洗澡是患沙眼的保护因素(OR=0.433),经常用手揉眼睛及父亲近0.5a眼睛有异物感是患沙眼的危险因素(OR值分别为3.150和2.726).结论 外来务工人员子女沙眼患病率较高,纠正学生不良用眼或卫生习惯、转变家长不正确的医疗观念以及及时、规范的治疗是预防与控制沙眼的有效手段.     

上海市闵行区华漕社区农民工学校学生沙眼患病情况调查

目的调查了解上海市闵行区华漕社区农民工学校学生沙眼的患病情况,并分析其影响因素。方法随机抽取华漕社区1所农民工学校和1所本地学校进行沙眼普查及沙眼问卷调查,比较2校的沙眼患病率并分析其影响因素。所有被调查对象均进行临床检查。结果调查农民工学校1 529名学生中,临床诊断194名学生患有沙眼,沙眼患病率为12.69%;本地学校975名学生当中,临床诊断52名学生患有沙眼,沙眼患病率为5.33%。农民工学校学生沙眼患病率明显高于本地学校(P<0.05);危险因素分析表明沙眼与是否共用毛巾、饭前便后洗手、用脏手揉眼睛、游泳、居住环境等因素密切相关。结论该社区农民工学校沙眼患病率仍较高,社区医院需每年对农民工学校学生进行沙眼普查,加大对农民工学生及家长的个人卫生习惯行为干预,增加学生对沙眼的认识。     

Neurologic Hazards of Diving

The results of a trachoma survey of 58,480 primary and junior high school students in Naha, Okinawa were compared to findings from two earlier, smaller surveys carried out in five rural villages elsewhere in the Ryukyu Islands. The overall prevalence of trachoma in Naha school children was 4.1% with girls predominating in the pre-school age groups and hoys among older children. Trachoma prevalence in Tonaki, the only village of the five without a piped water supply, was significantly greater than that for Naha or the other villages. A similar picture emerged when Naha was compared to the city of Ishikawa, which, like Tonaki, lacks a piped, treated water supply. It appears that a piped water supply decreases trachoma prevalence. The reasons for this are probably more closely related to the different patterns of water utilization in water-scarce and water-rich areas than to purity of water per se.     

Active trachoma in children aged three to nine years in rural communities in Ethiopia: prevalence, indicators and risk factors

Trachoma is the most important infectious cause of blindness worldwide. In two rural populations in Ethiopia, a programme of preventative and treatment measures was initiated in May 2002. A baseline survey was conducted to evaluate the effect of this programme on the prevalence of active trachoma. A total of 1960 children aged 3-9 years, from 915 households in 40 communities, were examined for the presence of active trachoma. Demographic and household information was collected using questionnaires and household amenities and environmental conditions were observed. Overall, 72% of children had active trachoma. Twenty percent of children aged nine years had trachomatous scarring. In children, discharge in the eyes and flies on the eyes were significant indicators of trachoma (odds ratio [OR] = 3.0, 95% CI 1.94-4.55 and OR = 3.4, 95% CI 2.37-4.88, respectively). Frequency of washing children, a clean environment and hygienic disposal of excrement were significant preventative factors for active trachoma. Prevalence of active trachoma varies widely between and within districts. Risk factors comprise a mix of individual characteristics and household factors. This study demonstrates the need for broad target interventions and a flexible approach to the prevention of trachoma in high prevalence endemic rural populations.     

Reliability of clinical diagnosis in identifying infectious trachoma in a low-prevalence area of Nepal.

The WHO Alliance for Global Elimination of Trachoma by 2020 has increased the need to identify ocular chlamydial infections by clinical examination in areas of both high and low prevalence. The relationship between clinically active trachoma (as defined by clinical examination) and chlamydial infection is known for areas with hyperendemic trachoma, but not for areas with a low prevalence of the clinical disease. In the present study, we examined, photographed, and DNA tested the conjunctivae of children in the Surkhet district of mid-western Nepal, an area known to have a low prevalence of clinically active trachoma. Although 6% of the children aged 10 years and under were found to have clinically active trachoma, none were found to have chlamydia infection by the most sensitive DNA amplification tests available. A very low prevalence of clinically active trachoma is not necessarily evidence of the presence of chlamydial infection. Therefore, the WHO policy of not recommending an intensive trachoma control effort when the prevalence of clinically active trachoma is less than 10% in children is appropriate for this area of Nepal.     

The prevalence of Chlamydia trachomatis infection among mothers of children with trachoma

The authors studied the epidemiology of Chlamydia trachomatis infection in a trachoma-endemic area of central Kenya. Children with abnormal ocular discharge were evaluated for clinical evidence of trachoma and were cultured for C. trachomatis. Isolated strains of C. trachomatis were immunotyped with monoclonal antibodies. Overall, 221 children from 207 families were evaluated. Clinically, 91 children (41%) had trachomatous follicular inflammation, and 130 (59%) had papillary hypertrophy without visible follicle and were labeled as having mucopurulent conjunctivitis. C. trachomatis was isolated from 31 of 91 children with trachoma (34%) and 17 of 130 children with conjunctivitis (13%) (p less than 0.001). Twenty-two C. trachomatis strains were immunotyped: 17 were from children with trachoma (nine type A, one A/L2, five B, one Ba, and one E) and five were from children with conjunctivitis (two A, one Ba, one D, and one F). A total of 168 mothers were evaluated for cervical C. trachomatis infection, and seven (4%) were culture-positive. Two strains were immunotyped as serovar E. The authors conclude that C. trachomatis ocular infections are due to heterogeneous serovars in this area, that most cases of trachoma are due to C. trachomatis infection with the classic trachoma serovars (A, B, or Ba), and that cervical C. trachomatis infection is uncommon among mothers of children with trachoma.     

Water cost and availability: key determinants of family hygiene in a Peruvian shantytown.

OBJECTIVES. This study was conducted to determine whether poor hygiene practices are owing to difficulty in getting enough water and/or to ignorance of sanitary principles. METHODS. In a water-scarce shantytown in Lima, Peru, we observed in 12-hour periods over 3 consecutive days the amount of water and soap used for personal and domestic activities in 53 families and the frequency with which direct fecal contamination of hands was interrupted by washing. We also surveyed women in a similar shantytown concerning their knowledge of hygiene to ascertain whether noncompliance was owing to ignorance. RESULTS. Three hundred fecal contamination events were registered, of which only 38 (13%) were interrupted by hand washing within 15 minutes. The mean 12-hour per capita amount of water and soap used by the families was low. More than 80% of the water stored by these families had fecal coliforms. Yet the level of knowledge concerning the importance of hand washing and other hygienic practices was high. CONCLUSIONS. In water-scarce areas, sanitary education programs probably will not change hygiene practices. In these areas, an adequate supply of water is essential for good hygiene.     

Epidemiology of trachoma in Bebedouro State of S?o Paulo, Brazil: prevalence and risk factors.

Trachoma was considered to have been 'eradicated' from the state of S?o Paulo, Brazil, until 1982 when a number of new cases of trachoma were reported in preschool children in Bebedouro, a small town in northwestern S?o Paulo. A household survey was undertaken to assess the prevalence and epidemiological characteristics of trachoma. A total of 2939 people of all ages was examined having been selected from a two-stage probalilistic household sampling frame based on census data. Overall, 7.2% of the population had evidence of one or more signs of trachoma and 2.1% had inflammatory trachoma. Inflammatory trachoma was more common in children aged one to ten years, especially in the peripheral urban and rural areas, and was more common in boys. The presence of chlamydia was confirmed by direct fluorescent antibody cytology. No cases of blindness due to trachoma were seen. A number of socioeconomic and hygiene variables were studied in order to determine the independent risk factors for trachoma in a household. Variables significantly associated with the occurrence of trachoma in the household were the number of children in the house aged one to ten years, the 'per capita' water consumption, the frequency of garbage collections, source of water, and the educational level of the head of household. Clustering of trachoma in different parts of this community was entirely explained by the concentration of households with these characteristics.     

Risk factors for the transmission of diarrhoea in children: a case-control study in rural Malaysia.

In response to a recorded increasing incidence of diarrhoea in Tumpat District, Malaysia, a case-control study was performed to identify modifiable risk factors for the transmission of diarrhoea, in children aged 4-59 months. Ninety-eight pairs of children, matched on age and sex, were recruited prospectively from health centres. Exposure status was determined during a home visit. Interviewers were 'blinded' as to the disease status of each child. Odds ratios were measured through matched pair analysis and conditional logistic regression. Risk factors for diarrhoea identified were: reported--drinking of unboiled water, storage of cooked food before consumption and bottle feeding; and observations--animals inside the house and absence of washing water in latrines. Water quality, source of drinking water, reported hand washing behaviour, indiscriminate defecation by children, cup use and the absence of a functional latrine were not associated with diarrhoea. Nonsignificant associations were found for: accessibility of washing water source, type of water storage container and use of fly covers for food.     

An index of community ocular Chlamydia trachomatis load for control of trachoma

Quantitative PCR (Q-PCR) technology has recently been applied to the measurement of ocular loads of Chlamydia trachomatis. We present an index called the community ocular C. trachomatis load (COCTL) which is similar to the community microfilarial load (CMFL) of onchocerciasis. Our index has the advantage of being scale-independent so that, for example, percentage changes are the same whether calculated per eye swab or per Q-PCR capillary. The COCTL for a population or subgroup is formed by adding the arbitrary concentration of 1 organism per ml to each individual Q-PCR quantification, calculating the geometric mean, and finally subtracting 1 per ml again. The use of the COCTL is illustrated in a study of trachoma in northern Tanzania. The COCTL is higher in people with clinical trachoma than those without (5.8 organisms per swab vs. 0.1), and in children aged six months to ten years than in the overall population (1.1 vs. 0.4). The COCTL index is potentially useful for sentinel sites, operational research and calibration of clinical measures of trachoma.     

The epidemiology of trachoma in central Tanzania.

Trachoma is the leading infectious cause of blindness worldwide and data are needed on the epidemiological characteristics of active and residual disease in hyperendemic areas. This study describes the epidemiological characteristics of trachoma in Central Tanzania. Active, inflammatory disease peaks in pre-school children, with 60% showing signs of trachoma. Evidence of past infection, scarring, trichiasis, and corneal opacity, rose with age. In this population, 8% of those over age 55 had trichiasis/entropion. Females of all ages had more trachoma than males, with a fourfold increased risk of trichiasis observed in females. Women who were taking care of children appeared to have more active disease than non-caretakers. Clear evidence of clustering of trachoma by village, and within village, by neighbourhood was found. Clustering persisted even after accounting for differences in distance to water, local religion, and proportion of children with unclean faces. These findings have important implications for a trachoma control strategy.     

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.