Adherence to Point-of-Use Water Treatment over Short-Term Implementation: Parallel Crossover Trials of Flocculation-Disinfection Sachets in Pakistan and Zambia.

The health benefits of point-of-use (POU) water treatment can only be realized through high adherence: correct, consistent, and sustained use. We conducted parallel randomized, longitudinal crossover trials measuring short-term adherence to two single-use flocculant-disinfectant sachets in Pakistan and Zambia. In both trials, adherence declined sharply for both products over the eight week surveillance periods, with overall lower adherence to both products in Zambia. There was no significant difference in adherence between the two products. Estimated median daily production of treated water dropped over the crossover period from 2.5 to 1.4 L person-1 day-1 (46% decline) in Pakistan and from 1.4 to 1.1 L person-1 day-1 (21% decline) in Zambia. The percentage of surveillance points with detectable total chlorine in household drinking water declined from 70% to 49% in Pakistan and rose marginally from 28% to 30% in Zambia. The relatively low and decreasing adherence observed in this study suggests that these products would have provided little protection from waterborne disease risk in these settings. Our findings underscore the challenge of achieving high adherence to POU water treatment, even under conditions of short-term adoption with intensive follow-up.

The public health significance of latrines discharging to groundwater used for drinking.

Faecal contamination of groundwater from pit latrines is widely perceived as a major threat to the safety of drinking water for several billion people in rural and peri-urban areas worldwide. On the floodplains of the Ganges-Brahmaputra-Meghna delta in Bangladesh, we constructed latrines and monitored piezometer nests monthly for two years. We detected faecal coliforms (FC) in 3.3-23.3% of samples at four sites. We differentiate a near-field, characterised by high concentrations and frequent, persistent and contiguous contamination in all directions, and a far-field characterised by rare, impersistent, discontinuous low-level detections in variable directions. Far-field FC concentrations at four sites exceeded 0 and 10 cfu/100 ml in 2.4-9.6% and 0.2-2.3% of sampling events respectively. The lesser contamination of in-situ groundwater compared to water at the point-of-collection from domestic wells, which itself is less contaminated than at the point-of-consumption, demonstrates the importance of recontamination in the well-pump system. We present a conceptual model comprising four sub-pathways: the latrine-aquifer interface (near-field); groundwater flowing from latrine to well (far-field); the well-pump system; and post-collection handling and storage. Applying a hypothetical dose-response model suggests that 1-2% of the diarrhoeal disease burden from drinking water is derived from the aquifer, 29% from the well-pump system, and 70% from post-collection handling. The important implications are (i) that leakage from pit latrines is a minor contributor to faecal contamination of drinking water in alluvial-deltaic terrains; (ii) fears of increased groundwater pollution should not constrain expanding latrine coverage, and (iii) that more attention should be given to reducing contamination around the well-head.

Interventions to improve water quality for preventing diarrhoea.

BACKGROUND: Diarrhoeal diseases are a leading cause of mortality and morbidity, especially among young children in developing countries. While many of the infectious agents associated with diarrhoeal disease are potentially waterborne, the evidence for reducing diarrhoea in settings where it is endemic by improving the microbiological quality of drinking water has been equivocal. OBJECTIVES: To assess the effectiveness of interventions to improve water quality for preventing diarrhoea. SEARCH STRATEGY: We searched the Cochrane Infectious Diseases Group Specialized Register (December 2005), CENTRAL (The Cochrane Library 2005, Issue 4), MEDLINE (December 2005), EMBASE (December 2005), and LILACS (December 2005). We also handsearched relevant conference proceedings, contacted researchers and organizations working in the field, and checked references from identified studies. SELECTION CRITERIA: Randomized and quasi-randomized controlled trials comparing interventions aimed at improving the microbiological quality of drinking water with no intervention in children and adults living in settings where diarrhoeal disease is endemic. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data. We used meta-analyses to estimate pooled measures of effect, where appropriate, and investigated potential sources of heterogeneity using subgroup analyses. MAIN RESULTS: Thirty trials (including 38 independent comparisons) covering over 53,000 participants met the inclusion criteria. Differences between the trials limited the comparability of results and pooling by meta-analysis. In general, the evidence suggests that interventions to improve the microbiological quality of drinking water are effective in preventing diarrhoea both for populations of all ages and children less than five years old. Subgroup analyses suggest that household interventions are more effective in preventing diarrhoea than interventions at the water source. Effectiveness was positively associated with compliance. Effectiveness was not conditioned on the presence of improved water supplies or sanitation in the study setting, and was not enhanced by combining the intervention to improve water quality with other common environmental interventions intended to prevent diarrhoea. AUTHORS' CONCLUSIONS: Interventions to improve water quality are generally effective in preventing diarrhoea, and interventions to improve water quality at the household level are more effective than those at the source. Significant heterogeneity among the trials suggests that the actual level of effectiveness may depend on a variety of conditions that research to date cannot fully explain. Rigorous, blinded, multi-arm randomized controlled trials conducted over a longer duration in a variety if settings may help clarify the potential effectiveness.

Asymptomatic giardiasis and growth in young children; a longitudinal study in Salvador, Brazil.

This study sought to assess the effect of giardiasis on growth of young children. In Salvador, northeast Brazil, 597 children initially aged 6 to 45 months were followed for a year in 1998/9, measured anthropometrically thrice, every 6 months, and monitored for diarrhoea prevalence twice weekly. Stool samples were collected and examined during the second round of anthropometry, and infected children were treated 39 days later, on average (S.D. 20 days). For each 6-month interval, the gains in z-scores of infected and uninfected children were compared, after adjustment for potential confounding factors, including longitudinal prevalence of diarrhoea. No significant difference was found for the first interval but in the second, the gain in adjusted height-for-age z-score was 0.09 less in infected than uninfected children, equivalent to a difference in height gain of 0.5 cm. The shortfall in growth was greater in children who remained free of diarrhoea, and was significantly correlated with the proportion of the second interval during which the child had remained untreated. We conclude that Giardia can impede child growth even when asymptomatic, presumably through malabsorption. This finding challenges the view that young children found to have asymptomatic giardiasis in developing countries should not be treated.

Is there an association between bacteriological drinking water quality and childhood diarrhoea in developing countries?

To investigate the association between bacteriological drinking water quality and incidence of diarrhoea, we conducted a 1-year prospective study in the southern Punjab, Pakistan. Diarrhoea episodes, drinking water sources and drinking water quality were monitored weekly among children younger than 5 years in 200 households. We found no association between the incidence of childhood diarrhoea and the number of Escherichia coli in the drinking water sources (the public domain). A possible trend was seen relating the number of E. coli in the household storage containers (the domestic domain) and diarrhoea incidence, but this did not reach statistical significance. Faecal contamination levels in household water containers were generally high even when the source water was of good quality. Under conditions such as this, it is questionable whether public water treatment will have a significant impact on the incidence of endemic childhood diarrhoea.

Environmental interventions and the pattern of geohelminth infections in Salvador, Brazil.

This paper reports a longitudinal study, conducted in 1989/90, of 1893 children aged 5 to 14 years in 9 poor urban areas of the city of Salvador (population 2.44 million), capital of Bahia State in northeast Brazil. Stool examinations were performed to measure nematode infection and reinfection 9 months after treatment, and an extensive questionnaire was applied to collect information on each child and on the conditions of the household. Comparison of areas with different levels of infrastructure showed the following trends as the level of community sanitation improved: clustering of cases by household became more significant, predisposition of individuals to reinfection and to heavy infection became more marked, and infections with different species were increasingly aggregated in the same individuals. These results suggest that sewerage and drainage can significantly reduce transmission of intestinal nematode infections in the public domain, but that other measures are required to control transmission within the household.

Risk factors for infection with Giardia duodenalis in pre-school children in the city of Salvador, Brazil.

A cross-sectional study of 694 children aged 2 to 45 months selected from 30 clusters throughout the city of Salvador, Bahia (pop. 2.3 million) was carried out as part of a longitudinal study of diarrhoea in order to identify risk factors for infection with Giardia duodenalis. Variables studied included three social and demographic factors (such as mother's education and marital status), five relating to the peri-domestic environment (rubbish disposal, open sewers, paving of the street), seven relating to the home itself (house construction, susceptibility to flooding, water supply and sanitation) as well as a score for hygiene behaviour based on structured observation. After multivariate analysis using a hierarchical model, only four significant risk factors were found: (a) number of children in the household under five years (b) rubbish not collected from the house (c) presence of visible sewage nearby, and (d) absence of a toilet. All four were significant at the 1% level.

Childhood diarrhea and observed hygiene behavior in Salvador, Brazil.

Brief biweekly home visits, made as part of a cohort study of diarrhea in young children under age 5 years that was carried out in Salvador, Brazil, in 1998-1999, were used as a low-cost way to collect structured observation data on domestic hygiene behavior. Field-workers were trained to check a list of 23 forms of hygienic or unhygienic behavior by the child or the child's caretaker, if any behaviors were seen during the visit. Children were grouped according to whether mainly unhygienic behavior or mainly hygienic behavior had been recorded. This permitted study of the determinants of hygiene behavior and of its role in the transmission or prevention of diarrheal disease. Observations were recorded on roughly one visit in 20. Households with adequate excreta disposal were significantly more likely to be in the "mainly hygienic" group. The prevalence of diarrhea among children for whom mainly unhygienic behavior was recorded was 2.2 times that among children in the "mainly hygienic" group. The relative risk for prevalence was 2.2 (95% confidence interval: 1.7, 2.8). The relative risk fell to 1.9 (95% confidence interval: 1.5, 2.5) after data were controlled for confounding, but the difference was still highly significant.

Sanitation in the developing world: current status and future solutions.

More than a third of the world's population (2.4 billion people) lacks access to adequate excreta disposal. Four in five of these unserved people are in Asia, with approximately one in five in both India and China, respectively. Even in large Asian cities, less than half of those served are using sewerage systems; the others use on-site systems, from pit latrines to septic tanks. Most have been installed by householders or builders employed by them, rather than by government or municipal agencies. Governments, international agencies and municipalities can never hope to meet the immense gap in provision unless they promote sanitation with a marketing approach. A latrine is a consumer durable which must be sold. It is often considered that the constraint to increasing sanitation coverage is a lack of demand, but there is often a lack of supply of appropriate products, and latrine designs are often too expensive for the poor, requiring subsidies which are captured by the better-off. More market research is needed to define the right product and how best to stimulate demand. Where subsidies are used, the promotion, not the production of the latrines must be subsidised to prevent middle-class capture of the subsidy. Promotion is probably best performed by different agencies from those that build latrines. The expertise and marketing capacity of the private sector needs to be brought into play, and public bodies must learn to assist it effectively in bringing sanitation to all.

The epidemiology of hepatitis A in Rio de Janeiro: environmental and domestic risk factors.

A serological study of hepatitis A was carried out in low-income areas scheduled for a major sanitation programme in Rio de Janeiro, Brazil. Blood spots were collected by finger puncture and transported on filter paper, and total antibodies to hepatitis A virus were detected by ELISA. Households were also interviewed to collect information on their environmental conditions and socio-economic status. A generalized linear model using a complementary log-log function was fitted to the data, using the logarithm of age as an explanatory variable to derive adjusted rate ratios (RR). The risk of infection was greater among households with 2-3 members per room (RR = 1.4; 95% CI = 1.04-1.8) or more than three per room (RR = 1.5; 95% CI = 1.2-2.0). People living on hilltops (RR = 1.5; 95% CI = 1.02-2.2), near to open sewers (RR = 1.2; 95% CI = 1.03-1.5) or lacking a kitchen (RR = 1.4; 95% CI = 1.08-1.9) were also at greater risk than others. The number of taps and water-using fittings in the house was associated with a protective effect (RR = 0.9 for each tap; 95% CI = 0.9-0.98). A significant protective association was found with maternal education but not with gender or household income. The results do not suggest a strong association with water quality. Ownership of a ceramic water filter was associated with a protective effect on the margin of significance, but the practice of boiling drinking-water was not, nor was the type of water source used. The results suggest that that the risk of infection with hepatitis A is determined by environmental variables in the domestic and public domains.

Review of the evidence base for the 'F' and 'E' components of the SAFE strategy for trachoma control.

Community control of trachoma as a blinding disease is based on the SAFE strategy of Surgery, Antibiotic therapy, Facial cleanliness and Environmental improvement. Surgery and antibiotic therapy currently dominate most programmes. Blindness from trachoma results from frequent infections repeated over many years, so ultimate success requires the reduction of transmission. This is only likely to be sustainable through the F and E components of SAFE. Environmental improvement with access to water, enhanced hygiene and better sanitation reduces trachoma transmission and the blinding sequelae eventually disappear. Transmission routes and factors that cause this are not known and consequently no single specific tool for F and E is in place. Evidence from intervention studies shows that the promotion of face-washing gave modest gains for intense effort and a pilot study showed that trachoma transmission was reduced in the absence of eye-seeking flies. Other studies have shown that latrines and improved access to water are associated with a lower prevalence of active trachoma. There is likely to be a long-term beneficial effect of a combination of improved water supplies, provision of latrines, facial hygiene promotion through established infrastructure and control of eye-seeking flies. Each of these interventions offers additional public health and other benefits in its own right. Further research on the routes of transmission, the role of hygiene and means of sustainable fly control should be a priority.

Domestic hygiene and diarrhoea - pinpointing the problem.

Improving domestic hygiene practices is potentially one of the most effective means of reducing the global burden of diarrhoeal diseases in children. However, encouraging behaviour change is a complex and uncertain business. If hygiene promotion is to succeed, it needs to identify and target only those few hygiene practices which are the major source of risk in any setting. Using biological reasoning, we hypothesize that any behaviours which prevent stools from getting into the domestic arena, the child's main habitat, are likely to have a greater impact on health than those practices which prevent pathogens in the environment from being ingested. Hence safe stool disposal, a primary barrier to transmission, may be more important than hand-washing before eating, which constitutes a secondary barrier, for example. We review the epidemiological evidence for the effect of primary and secondary barrier behaviours and suggest that it supports this conclusion. In the absence of local evidence to the contrary, hygiene promotion programmes should give priority to the safe disposal of faecal material and the adequate washing of hands after contact with adult and child stools.

Reviewing the health impacts of improvements in water supply.

PIP: This article reviews the impact of water quality and quantity on the transmission of water-related infectious diseases and on improved health in general in South Africa. Water quantity has a more important impact on improved health than water quality. Quality may vary between point of source and point of use. Combined water and sanitation improvements are more effective than single interventions. Children from families who used larger quantities of water received greater benefits from increased supplies. In-house supplies of water were related to greater water consumption (WC). Per capita WC was related inversely to the distance to the source of supply. Greater WC for hygiene and other purposes impacts on health. Shorter distances to water supplies was related to a 30% reduction in prevalence of trachoma or "river blindness." Prevalence of infectious conjunctivitis was not related to water access. Prevalence of ascariasis (intestinal worms) can be reduced by 12% with well access in the yard, and by 37% with indoor water supplies. Economic benefits of improved water supplies may vary between locations. Water vending is prohibitively expensive for the poor. The extent of economic benefit of improved water supplies depends on the characteristics of existing and improved sources, such as price, reliability, and quality. A major determinant of benefit is the reliability of both existing and improved supply. A very large cost saving benefit is time. Women and children may save a major portion of daily caloric intake, prevent injuries from carrying water, and permit greater female school attendance.^ieng

More water: better health.

PIP: This article discusses the role of clean water in preventing fecal-oral transmission of infections, skin and eye diseases, water-based diseases, and insect vector diseases. Improvements to water quality are not sufficient to reduce infection. There is a need to educate people about appropriate hygiene and hand washing with soap and cleanliness of storage and eating utensils. Access to clean water is also important. Access to water reduces the household burden for women and children in time and effort. Households farthest from a supply of clean water would benefit the most from access to a clean water supply in time, effort, and money saved. The World Bank found that just the time saved in water collection was sufficient to justify house connections to a public supply of water. Most people would gladly pay for a water supply to be connected to their house. Free water at standpipes does not interfere with the demand for house connections. It was found that when water sources were shifted to locations closer than 1 km, the shift resulted in an increase in the amount of water used. When round-trip water collection takes about 30 minutes, level of use remains constant. When a water supply is moved to within a few yards of the house or piped indoors, use doubles or triples. Fecal contamination of water causes high rates of diarrheal disease, which kills over 3 million children per year. Diseases, such as cholera and typhoid fever, are transmitted through water-fecal links as well as contaminated food, fingers, utensils, and even clothes. More water available in the home would prevent women from using a corner of their sari to wipe dishes, wipe faces, and wipe a child's bottom. Large storage tanks do not prevent the presence of parasitic worms or insect vectors in the water supply.^ieng

Twenty years of cutaneous leishmaniasis in Aleppo, Syria.

Cutaneous leishmaniasis caused by Leishmania tropica has long been associated with Aleppo in Syria. For 20 years up to the mid-1980s, the number of cases reported annually in the city and environs has remained low, not exceeding a few hundred. Since then, there has been a sudden increase to several thousand cases reported each year. The increase seems too great and too sudden to be attributable to improved case detection. Insecticide spraying, begun in 1991, was followed by a reduction in number of cases in 1992, but numbers increased subsequently in spite of continued spraying. The cases are found mainly in areas undergoing development outside the old centre of the city, and may be associated with poor waste disposal and heaps of construction waste.

Global eradication of Guinea worm.

Little more than a decade ago, it was estimated that over three million cases of dracunculiasis occurred worldwide. Since then, the numbers have fallen dramatically, thanks to the water supply initiatives of the 1980s and, more recently, the national guinea worm eradication programmes implemented in a score of endemic countries. Hervé Periès and Sandy Cairncross discuss how eradication will require the containment of cases in the remaining endemic areas, together with the simultaneous strengthening of surveillance to permit the certification of eradication. This aim requires existing strategies to be adapted to maintain their efficacy and also to improve their sustainability and cost-effectiveness. Sudan with its civil war, and more than a hundred thousand reported cases, remains a major obstacle to rapid achievement of the goal.