Cartography of trachoma in Mali: results of a national survey

Prior to a campaign to eliminate blinding trachoma, a survey of the prevalence of the disease was conducted in the seven administrative regions of Mali between March 1996 and June 1997. In each region (with the exception of Bamako District) a random sample of thirty clusters was taken from the general population, in accordance with the principle of probability proportionate to the size of the communities. All children under 10 years of age and all women over 14 years were examined. The simplified coding proposed by WHO was used for data gathering. A total of 15,310 children and 11,530 women were examined. The prevalence of active trachoma, follicular (TF) or intense (TI), was estimated to be 34.9% among children under 10 years of age (95% CI: 32.3-37.6). The prevalence of TI showing the intensity of trachoma was 4.2% (95% CI: 3.5-5.0) among the same children. The prevalence increased up to the age of 3 years, when it reached 49.2%. The prevalence of TF/TI was 35.7% among boys and 34.3% among girls. The prevalence of entropion trichiasis among women over 14 years of age was 2.5% (95% CI: 2.1-2.9), and 1% had central corneal opacity (95% CI: 0.8-1.3). These prevalences increased with age, such that 10% of women over 70 years of age had trichiasis. By region of the country, the prevalence ranged from 23.1% of active trachoma among children in Ségou, to 46.2% in Gao. The prevalence of entropion trichiasis was 0.65% in Gao region and 3.9% in Koulikoro region. This survey allows the trachoma treatment needs of Mali to be quantified. We estimate that 1.09 million children under 10 years are carriers of active trachoma and require local or general antibiotic treatment. If all the under-10-year-olds from all villages where TF/TI exceeded 20% were to be treated, a total of 2.436 million children would be involved. A total of 85,000 adults should have surgery to correct trichiasis and avoid the onset of blindness.     

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.     

Trichiasis and geoclimatic factors in Mali

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

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.     

Risk factors for active trachoma in children and trichiasis in adults: a household survey in Amhara Regional State, Ethiopia

Identification of risk factors is essential for planning and implementing effective trachoma control programmes. We aimed to investigate risk factors for active trachoma and trichiasis in Amhara Regional State, Ethiopia. A survey was undertaken and eligible participants (children aged 1-9 years and adults aged 15 years and above) examined for trachoma. Risk factors were assessed through interviews and observations. Using ordinal logistic regression, associations between signs of active trachoma in children and potential risk factors were explored. Associations between trichiasis in adults and potential risk factors were investigated using conventional logistic regression. A total of 5427 children from 2845 households and 9098 adults from 4039 households were included in the analysis. Ocular discharge [odds ratio (OR)=5.9; 95% CI 4.8-7.2], nasal discharge (OR=1.6; 95% CI 1.3-1.9), thatch roof in household (OR=1.3; 95% CI 1.0-1.5), no electricity in household (OR=2.4; 95% CI 1.3-4.3) and increasing altitude (Ptrend<0.001) were independently associated with severity of active trachoma. Trichiasis was associated with increasing age (ORper 5 year increase=1.5; 95% CI 1.4-1.7), female gender (OR=4.5; 95% CI 3.5-5.8), increasing prevalence of active trachoma in children (Ptrend=0.003) and increasing altitude (Ptrend=0.015).     

Mapping the global distribution of trachoma

OBJECTIVE: We aimed to summarize and map the existing global population-based data on active trachoma and trichiasis. Detailed distribution maps of various infectious diseases have proved a valuable tool in their control. Such maps play an important role in assessing the magnitude of the problem, defining priority areas for control, monitoring changes, and advocacy. Until now, information on trachoma prevalence at within country levels has not been systematically collated, analysed and reported. METHODS: We gathered the last 18 years' worth of reported data on active trachoma in children aged less than 10 years, and the last 25 years of reported trichiasis in adults aged 15 years and over from 139 population-based surveys in 33 countries. We collated these data into one database using the "district" (second administrative level) as the standard unit of reporting. We used Geographical Information Systems as a database and cartographic tool to generate a global map of the prevalence of trachoma and trichiasis. FINDINGS: We obtained data on active trachoma and trichiasis from 18 countries in the WHO African Region, 6 in the Eastern Mediterranean Region, 3 in the South-East Asia Region, 3 in the Western Pacific Region and 2 in the Region of the Americas. In 23 countries suspected of having endemic trachoma no reliable district-level population-based data were available. In China and India, data were limited to a few districts. The data highlighted important regional differences and marked national variations in prevalence of active trachoma and trichiasis. CONCLUSION: This is the first attempt to summarize and map the existing population-based data on active trachoma and trichiasis. The lack of data in many countries remains an important obstacle to trachoma control efforts.     

Prevalence and control of trachoma in Australia, 1997-2004

This study aimed to document the prevalence of active trachoma and trichiasis from 1997 to 2003 and from 1987 to 2004, respectively, and to provide an overview of trachoma control activities in Australia in 2004. Prevalence data were obtained from state, territory and regional population health units and unpublished surveys. Information about trachoma control programs and activities currently implemented in Australia was obtained through structured interviews with staff involved in trachoma control. Active trachoma prevalence in Aboriginal and Torres Strait Islander children, ranging from 0-40 per cent, were reported from the Eastern Goldfields, Midwest-Murchison and Kimberley Population Health Units in Western Australia and the Northern Territory's Centre for Disease Control. Large differences in trachoma prevalence were reported within and between different regions and from different years in the same region. Recent surveys of trichiasis in Kimberley and Central Australian Aboriginal and Torres Strait Islander adults demonstrated a prevalence of 9-12 per cent in inland, desert areas. In contrast with developing countries where active trachoma and trichiasis are more common among adult women than men, Australian surveys have identified equal prevalence in both sexes. Interpretation of trachoma prevalence and inter-regional/state/national comparisons were hampered by lack of a uniform method of data collection and analysis. Trachoma control programs were implemented consistently in some communities, and irregularly and/or in piecemeal fashion in others. Trachoma control programs led by regional population health units working in collaboration with primary health care services were more likely to be consistently implemented over long periods of time. Trachoma is a significant public health issue in some Aboriginal communities within Australia. The Communicable Diseases Network Australia has developed guidelines for the public health management of trachoma which provide recommendations on trachoma screening, control and data collection trachoma for affected states and territories.     

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.     

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.     

Rapid trachoma assessment method (TRA): comparison with an exhaustive prevalence survey in a region of endemic trachoma in Mali

In 1997, the World Health Organization (WHO) endorsed a new strategy aimed at controlling blinding trachoma by 2020. The WHO developed a rapid assessment method for trachoma (TRA) for identifying communities affected by blinding trachoma and for ranking villages with endemic trachoma in order of priority for intervention. We applied this method to communities in Mali in which trachoma was prevalent, and compared the results with those of a classical prevalence survey. Seven villages from the Dogon region were first investigated using the rapid method. Members of the local community were asked to identify individuals with suspected trichiasis, using a diagram to help them with recognition. The individuals thus identified were then examined by an ophthalmic nurse for confirmation of the diagnosis. Fifty children aged less than ten years from poorer households were then selected. These children underwent ophthalmic examination, using a magnification of 2.5, and trachoma status was established. The next day, the villages were visited by an ophthalmologist who examined all of the inhabitants. The rapid assessment method identified 18 of the 52 patients requiring surgery. This method had a sensitivity of 34.6% and a specificity of 98%. The prevalence of active trachoma among children was 29.0% in the exhaustive survey and 29.9% for the rapid assessment method. Overall sensitivity was 54.6% and overall specificity 79.6%, as the two methods did not identify the same individuals. The Kappa coefficient, estimating agreement between observers, was 0.34. The ranking of the villages in order of priority differed slightly for the two methods. With the rapid assessment method, five of the seven villages were classified as having a prevalence of over 20% whereas, with the exhaustive survey, six of the seven villages fell into this category. TRA was not designed to replace epidemiological survey and the prevalence of trachoma should not be inferred from this method. However, it is a useful tool for determining the order of priority for intervention of communities at risk.     

The epidemiology of trachoma in Eastern Equatoria and Upper Nile States, southern Sudan

OBJECTIVE: Limited surveys and anecdotal data indicate that trachoma is endemic in the states of Eastern Equatoria and Upper Nile in southern Sudan. However, its magnitude and geographical distribution are largely unknown. We conducted surveys to ascertain the prevalence and geographical distribution of trachoma, and to identify targets for control interventions. METHODS: Population-based cross-sectional surveys were conducted in nine sites in southern Sudan between September 2001 and June 2004. Two-stage random cluster sampling with probability proportional to size was used to select the sample. Trachoma grading was done using the WHO simplified grading system. FINDINGS: A total of 17 016 persons were examined, a response rate of 86.1% of the enumerated population. Prevalence of signs of active trachoma in children aged 1-9 years was: TF=53.7% (95% confidence interval (CI)=52.1-55.3); TI=42.7% (95% CI=41.2-44.2); TF and/or TI=64.1% (95% CI=62.5-65.5). Prevalence of trichiasis (TT) in children aged less than 15 years was 1.2% (95% CI=0.9-1.4), while TT prevalence in persons aged 15 years and above was 9.2% (95% CI=8.6-9.9). Women were more likely to have trichiasis compared to men (odds ratio (OR)=1.57; 95% CI=1.34-1.84). Tentative extrapolation to the states of Eastern Equatoria and Upper Nile estimates that there is a backlog of 178,250 (lower and upper bounds=156,027-205,995) persons requiring surgery and the entire population, estimated to be over 3.9 million, is in need of the SAFE strategy to control blinding trachoma. CONCLUSION: Trachoma is a public health problem in all nine of the study sites surveyed. The unusually high prevalence of active trachoma and TT in children points to the severity of the problem. There is urgent need to implement trachoma control interventions in trachoma endemic regions of southern Sudan.     

Incidence of trichiasis in a cohort of women with and without scarring

BACKGROUND: Blindness from trachoma is a significant problem for many underdeveloped countries. While active trachoma is common in children, trichiasis, the potentially blinding sequella, develops in adulthood and affects mainly women. Little is known about factors associated with the development of trichiasis. METHODS: The 7-year incidence of trichiasis and its association with ocular chlamydia infection was examined in a cohort of women from a hyperendemic area. A total of 4,932 women 18 years and older, living in 11 villages in Central Tanzania, were examined in 1989. A follow-up examination in 1996 was performed on all women with scars living in six of the 11 villages and on a random sample of women without scars from the same villages. Trachoma was graded clinically, chlamydia infection was ascertained at follow-up using polymerase chain reaction-enzyme immunoassay (PCR-EIA). RESULTS: A total 523 of the women with scars and 503 of the women without scars were re-examined. Forty-eight of the women with scars (incidence, 9.2%) and three of the women without scars (0.6%) developed trichiasis in the 7-year period. Prevalence of chlamydia infection was significantly higher in the group with scars (11.7% versus 7.1%). Trichiasis cases were more likely to be older, and to have chlamydia infection at follow-up odds ratio (95% confidence interval) 2.5 (1.1-5.7). CONCLUSION: The 7-year incidence rate in the population with scars was high, over 1% per year. Ocular chlamydia infection was more common in the group with scars at baseline and was also associated with being a trichiasis case, suggesting the importance of potentially long-term chlamydia infection in the progression to trichiasis. Antibiotic distribution programmes for trachoma control should include women with scars.     

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.     

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.     

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.     

A longitudinal study of trachoma in a Gambian village: implications concerning the pathogenesis of chlamydial infection.

In order to investigate risk factors for the acquisition of trachoma, and to study the effect of continued exposure to ocular chlamydial infection on the severity of inflammatory trachoma and its cicatricial sequelae, a longitudinal study was conducted in a Gambian village. Over a 20-month period, the incidence of active (inflammatory) trachoma was significantly higher among those sharing a bedroom with an active case (64/561, 11.4%) than among those who were not exposed in this way (37/658, 5.6%) (relative risk 1.97, 95% confidence interval 1.33-2.90). There was a positive trend in the odds ratio for severe to moderate inflammatory disease versus mild disease as the number of active cases in the bedroom increased, but this failed to achieve statistical significance (P = 0.0506). Individuals with inflammatory trachoma of moderate or severe intensity at one survey were significantly more likely than others to have moderate or severe inflammatory changes at a previous or subsequent survey (odds ratio 14.9, 95% confidence interval 3.9-68.0), implying that host factors may be more important determinants of severity than the frequency of exposure to reinfection.     

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.     

Surveillance report for active trachoma, 2006: National Trachoma Surveillance and Reporting Unit

The National Trachoma Surveillance and Reporting Unit (NTSRU) was established in November 2006 to improve the quality and consistency of data collection and reporting of active trachoma in Australia. Active trachoma data collected in 2006, prior to the commencement of the NTSRU, were reported by the Northern Territory, South Australia and Western Australia. In most regions, Aboriginal children aged 5-9 years were screened for signs of active trachoma, following the World Health Organization simplified trachoma grading system. In the Northern Territory the Healthy School Aged Kids program conducted school-based screening for active trachoma in 74 schools in five regions (n = 2,253). In South Australia Aboriginal school children presented for active trachoma screening when an eye team visited five Aboriginal Community Controlled Health Services (n = 275). In Western Australia population health units in collaboration with staff from population health care services, conducted school based screening for active trachoma in 53 schools in four regions (n = 1,719). Regional active trachoma prevalence for 2006 varied between the states and the Northern Territory with reported prevalences ranging from: Northern Territory = 2.5%-30%, South Australia = 0%-25%, and Western Australia = 18%-53%. Few data were reported on facial cleanliness or other aspects of the SAFE strategy, and no data were reported for trichiasis.     

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 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.