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.     

The household distribution of trachoma in a Tanzanian village: an application of GIS to the study of trachoma

The distribution of active trachoma in Kahe Mpya, Tanzania, an endemic village of approximately 1000 people, was mapped spatially and analysed for associated risk factors and evidence of clustering. An association between distance to water source and active disease was demonstrated, although this was reduced after accounting for the lack of independence between cases in the same household. Significant clustering of active trachoma within households was demonstrated, adding support to the hypothesized importance of intra-familial transmission. The spatial distribution of trachoma was analysed using the spatial scan statistic, and evidence of clustering of active trachoma cases detected. Understanding the distribution of the disease has implications for understanding the dynamics of transmission and therefore appropriate control activities. The demonstrated spatial clustering suggests inter-familial as well as intra-familial transmission of infection may be common in this setting. The association between active trachoma and geographical information system (GIS) measured distance to water may be relevant for planning control measures.     

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 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.     

Rapid Trachoma Assessment in Kersa District,Southwest Ethiopia

Background

Trachoma is the leading cause of infectious blindness worldwide. Though trachoma can be treated with antibiotics (active trachoma) or surgery (trachomatous trichiasis), it is still endemic in most parts of Ethiopia. Despite the prevalence of this infectious disease in different parts of the country, district level data is lacking. This study was thus conducted to assess the prevalence estimate of trachoma and its risk factors in Kersa District, Southwest Ethiopia.

Methods

A community based cross sectional Rapid Assessment of Trachoma was conducted using a WHO guideline. Six sub-districts were selected from Kersa District based on primary high risk assessment and from each sub-district; 21–27 households were randomly selected. Active trachoma for children aged 1–9 years, trachomatous trichiasis for people above 15 years old and environmental risk factors for trachoma were assessed. Data were analyzed using SPSS version 16.

Results

The overall prevalence estimate of active trachoma was 25.2% (95% CI: 20.7–30.4%). Forty three percent of children had unclean faces, 11.5% of households had water source at more than half hour walking distance, 18.2% did not have functional latrine, and 95.3% of the households had solid waste disposal within a distance of 20 meters. Households with environmental risk factors were at an increased risk to active trachoma, but the association was not statistically significant (p>0.05). The prevalence estimate of trachomatous trichiasis inclusive of “trachoma suspects” was 4.5%.

Conclusion

Trachoma is endemic in Kersa District with active trachoma being a public health problem in the studied sub-districts. Hence, SAFE strategy should be implemented.     

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 and water use; a case control study in a Gambian village.

Trachoma is prevalent in many arid areas but data assessing the relationship between water use and trachoma are very scarce. This study compared 18 families having one or more active trachoma cases among the children with 16 trachoma-free families in the same village with respect to water use. Potential confounders such as family size, distance to water source, socio-economic indicators, and hygiene behaviour were assessed in the 2 groups. The families with trachoma were found to use significantly less water per person per day for washing children than did the control group (P = 0.033) with no evidence of confounding by the other measured variables. Low amounts of water for washing were also associated with unclean faces and impetigo in the children. If such a relationship can be substantiated it might provide the basis for effective and cheap interventions against trachoma.     

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.     

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.     

Analysis of the household distribution of trachoma in a Gambian village using a Monte Carlo simulation procedure

Studies on the household distribution of trachoma have reached conflicting conclusions. This paper describes a cross-sectional survey of endemic trachoma in a Gambian village. Cases of active trachoma were mapped, and the compound and household distribution of the disease analysed by a Monte Carlo simulation procedure which takes into account differences in the size and age distribution within individual households. Significant clustering of active trachoma cases both by village compound (p less than 0.0001) and bedroom (less than 0.05) were detected supporting the concept that intra-familial transmission of trachoma is important. There was no evidence of spatial clustering of rooms with higher than expected prevalence of trachoma. Clustering of disease in space or time provides important evidence of infectious aetiology and route of transmission. The methods discussed here are generally applicable in the study of other infectious diseases.     

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.     

Preliminary evidence that synanthropic flies contribute to the transmission of trachoma- causing Chlamydia trachomatis in Latin America

Synanthropic flies have been shown to be important mechanical vectors of Chlamydia trachomatis, which causes trachoma. However entomological studies have not been forthcoming in Latin America. This study assesses the relationship between household dipteran fly densities and active childhood trachoma in a village on Marajó Island, Pará state, Brazil. For 78 households, members were examined for signs of trachoma, relative abundance of potential trachoma vectors (Diptera, Chloropidae and Diptera, Muscidae) was quantified by trap counts, and additional measures of household hygiene associated with C. trachomatis transmission were assessed. Active childhood trachoma prevalence was 24.1% (45/187), present in 46.2% of sampled households with evidence of case clustering. Childhood prevalence was positively associated with increased fly densities, whereas indirect measures of sanitary conditions (latrine ownership and perceived importance of flies) showed a protective effect. This study indicates that C. trachomatis can be transmitted by synanthropic flies in this region of Latin America.     

Risk factors for active trachoma in The Gambia

Trachoma has been endemic in The Gambia for decades but national surveys indicate that the prevalence is falling. Risk factor data can help guide trachoma control efforts. This study investigated risk factors for active trachoma and ocular Chlamydia trachomatis infection in children aged below 10 years in two Gambian regions. The overall prevalence of C. trachomatis infection was only 0.3% (3/950) compared with 10.4% (311/2990) for active trachoma, therefore analyses were only performed for active trachoma. After adjustment, increased risk of trachoma was associated with being aged 1-2 years (odds ratio (OR) 2.20, 95% CI 1.07-4.52) and 3-5 years (OR 3.62, 95% CI 1.80-7.25) compared with <1 year, nasal discharge (OR 2.07, 95% CI 1.53-2.81), ocular discharge (OR 2.68, 95% CI 1.76-4.09) and there being at least one other child in the household with active trachoma (OR 11.28, 95% CI 8.31-15.31). Compared with other occupations, children of traders had reduced risk (OR 0.53, 95% CI 0.30-0.94). At the household level, only the presence of another child in the household with active trachoma was associated with increased risk of active trachoma, suggesting that current trachoma control interventions are effective at this level. In contrast, child-level factors were associated with increased risk after adjustment, indicating a need to increase control efforts at the child level.     

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.     

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

OBJECTIVE: 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. METHODS: 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. FINDINGS: 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. CONCLUSIONS: 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.     

Domestic dog ownership: a risk factor for human infection with Leishmania (Viannia) species

An epidemiological study has shown that cumulative, village prevalence of Leishmania (Viannia) infection in dogs ranges from 8% to 45% in Huánuco, Peru. Using data from a prospective survey of human American cutaneous leishmaniasis (ACL) collected during 1994-98, it was shown that the village-level risk of human ACL did not significantly increase with dog abundance, neither in absolute terms (P = 0.659) nor in relation to dog:human ratios (P = 0.213). A significant positive association was observed between risk of human ACL and village dog ACL prevalence (P = 0.022). When controlled for village dog ACL prevalence, there also was an association between the average number of dogs per household and risk of human ACL (P = 0.033). The results suggest that dogs play a role in the (peri)domestic transmission of Le. (Viannia) to humans in Huánuco and indicate that a control intervention targeting dogs to control human ACL is warranted.     

Relationship between distance to social gathering facilities and risk of trachoma for households in rural Tanzanian communities

Few studies have examined the physical isolation of households with trachoma cases. Thus, in this study, we sought to examine the association between household isolation, as measured by distance to social gathering facilities, and risk of trachoma. We hypothesized that households located closer to such facilities would have a decreased risk of trachoma, due to a variety of social, economic, and cultural reasons. To test this hypothesis we conducted a case-control study of 668 households (93 cases, 575 controls) in eight villages in Kongwa District, Tanzania, in 2007. Case households were defined as having a child aged 1–5 years with clinical signs of trachoma. Distance of household’s place of residence to three main social gathering facilities — bars/cafés, religious establishments, and commercial/government center — was measured with a portable geographic positioning system. Multiple logistic regression analyses, which controlled for potential confounders and accounted for clustering, demonstrated increased risk of trachoma with increasing distance to social gathering facilities. Compared with distances of ≤700 m, odds of trachoma were approximately two-fold higher for households living >1400 m from bars/cafés and from religious establishments, suggesting increased risk of trachoma for households at the fringes of communities. Targeting these isolated households with special programming along with dissemination through trusted social gathering facilities may improve effectiveness of current prevention efforts.     

Active trachoma in children in central Ethiopia: association with altitude

A cross-sectional study was conducted in the dry month of February 2000 in the Gurage Zone of Ethiopia (population over 1.5 million) to determine the magnitude of trachoma and blindness. A multistage cluster sampling was applied to identify the study subjects. Pre-school children (1-6 years) were examined for active trachoma by trained ophthalmic nurses. The prevalence of active trachoma in the 1-6-year-old age group was 56.5%, ranging from 5.7% (altitude > 3000 m) to 73.4% (altitude less than 2000 m) (P < 0.001). Active trachoma was more common in male children than in female children and peaked in the 3-year-old age group (63.2%), declining with age. The distance to a source of water for 45% of these households was only 15 min. Only 6% of the households had latrines. Confirmation of the association between active disease and altitude may assist with mapping of trachoma in Ethiopia and elsewhere. It is possible that fly density, higher in villages at low altitudes, contributed to the differences seen.     

Domestic hygiene behaviour of mothers with children aged 0-5 years old in Tayabo village,Nueva Ecija,the Philippines

A cross-sectional survey was carried out in a rural village in Nueva Ecija province in the Philippines to identify the association between mothers' hygiene behaviour and their socioeconomic status and household environment. A total of 206 mothers with children aged 0-5 years old participated in this study. Household visits with face-to-face interviews using a structured questionnaire and observation of household environments were conducted. Logistic regression analysis revealed that the frequency of water boiling in mothers was significantly associated with children aged under two years old and the availability of domestic electricity. Availability of domestic electricity, mother's educational level, possession of a private lavatory and of a private well were significant predictors of whether hand-washing with soap was practiced after defecation. For hand-washing with soap before feeding children, child's age under one year old and the volume of the water supply were statistically significant. The volume of the water supply was identified as a significant predictor. Although health educational programme participation rates were very high (83.2%), no significant association with hygiene behaviour was observed. This study indicates that improvements in water availability, household environment and health education may contribute to more frequent hand-washing.