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Objectives To evaluate the effectiveness of point of use water treatment with flocculent-disinfectant on reducing diarrhoea and the additional benefit of promoting hand washing with soap.
Methods The study was conducted in squatter settlements of Karachi, Pakistan, where diarrhoea is a leading cause of childhood death. Interventions were randomly assigned to 47 neighbourhoods. Households in 10 neighbourhoods received diluted bleach and a water vessel; nine neighbourhoods received soap and were encouraged to wash hands; nine neighbourhoods received flocculent-disinfectant water treatment and a water vessel; 10 neighbourhoods received disinfectant-disinfectant water treatment and soap and were encouraged to wash hands; and nine neighbourhoods were followed as controls. Field workers visited households at least once a week from April to December 2003 to promote use of the interventions and to collect data on diarrhoea.
Results Study participants in control neighbourhoods had diarrhoea on 5.2% of days. Compared to controls, participants living in intervention neighbourhoods had a lower prevalence of diarrhoea: 55% (95% CI 17%, 80%) lower in bleach and water vessel neighbourhoods, 51% (95% CI 12%, 76%) lower in hand washing promotion with soap neighbourhoods, 64% lower (95% CI 29%, 90%) in disinfectant-disinfectant neighbourhoods, and 55% (95% CI 18%, 80%) lower in disinfectant-disinfectant plus hand washing with soap neighbourhoods.
Conclusions With an intense community-based intervention and supplies provided free of cost, each of the home-based interventions significantly reduced diarrhoea. There was no benefit by combining hand washing promotion with water treatment.
Objectifs Evaluer l'efficacité du traitement de l'eau au point d'utilisation avec un désinfectant floculant sur la réduction des diarrhées et le bénéfice additionnel de la promotion du lavage des mains.
Méthodes l’étude a été conduite dans les installations d'habitations de fortune de Karachi au Pakistan où la diarrhée est la cause principale de mortalité infantile. Les interventions ont été assignées de façon randomisée à 47 quartiers. Dans 10 quartiers, les familles ont reçu de l'eau de javel diluée et des contenaires pour l'eau. Dans 9 quartiers, elles ont reçu du savon et ont été motivées pour le lavage des mains. Dans 9 quartiers, elles ont reçu le désinfectant floculant pour le traitement de l'eau et des contenaires pour l'eau. Dans 10 quartiers, elles ont reçu le désinfectant floculant et du savon et ont été motivées pour le lavage des mains. 9 quartiers ont été suivis comme contrôles. Les agents de terrain ont visité chaque famille au moins une fois par semaine, d'avril à décembre 2003 pour promouvoir l'utilisation des interventions et pour collecter des données sur la diarrhée.
Résultats Les participants dans les quartiers contrôles avaient la diarrhée sur 5,2% des jours. Comparés au contrôles, les participants des quartiers recevant l'intervention avaient une prévalence de diarrhée plus faible repartie comme suit: 55% (IC95%: 17–80) plus faible dans les quartiers ayant reçu l'eau de javel et des centenaires, 51% (IC95%: 12–76) plus faible dans les quartiers ayant reçu la promotion du lavage des mains, 64% (IC95%: 29–90) dans les quartiers ayant reçu le désinfectant floculant et 55% (IC95%: 18–80) plus faible dans les quartiers ayant reçu le désinfectant floculant en plus de savon pour le lavage des mains.
Conclusion Avec une forte intervention basée sur la communauté et des moyens procurés sans charge, chacune des interventions a entraîné une réduction significative de la diarrhée. Il n'y avait pas de bénéfice supplément en combinant la promotion du lavage des mains et le traitement de l'eau.
Objetivos Evaluar la efectividad del tratar el agua con desinfectante floculado en la reducción de la diarrea, así como los beneficios adicionales en la promoción del lavado de manos con jabón.
Métodos El estudio fue conducido en asentamientos ilegales de Karachi, Pakistán, en los que la diarrea es la principal causa de mortalidad infantil. Las intervenciones fueron asignadas aleatoriamente en 47 barrios. Las casas de 10 barrios recibieron lejía diluida y un recipiente para agua; en 9 barrios se entregó jabón y se les animó a que se lavasen las manos; en otros 9 barrios se entregó desinfectante floculado para tratamiento del agua y un recipiente para agua; 10 barrios recibieron desinfectante floculado para tratamiento del agua y jabón, y se les animó a que se lavaran las manos; y 9 barrios fueron seguidos como controles. Los trabajadores de campo visitaron las casas al menos una vez por semana, entre Abril y Diciembre del 2003, para promover el uso de la intervención y para recolectar datos sobre diarreas.
Resultados Los participantes de los barrios controles tuvieron diarrea en un 5.2% de los días. Comparado con los controles, los participantes que vivían en uno de los barrios en los que se intervino tuvieron una menor prevalencia de diarrea: 55% (95% IC 17%, 80%) menos en los barrios en los que se entregó lejía y un recipiente para el agua, 51% (95% IC 12%, 76%) menos en los barrios en los que se promovió el lavado de manos con jabón, 64% menos (95% IC 29%, 90%) en los barrios con desinfectante floculado, y 55% (95% IC 18%, 80%) menos en los barrios con desinfectante floculado más promoción del lavado de manos con jabón.
Conclusiones Con una intervención comunitaria intensiva y suministros gratuitos, cada una de las Intervenciones redujo la diarrea de forma significativa. No se halló beneficio en combinar la promoción del lavado de manos con el tratamiento del agua.
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Diarrhoea is a leading cause of childhood death globally (WHO 1999). When introduced separately, both point-of-use drinking water treatment and hand washing with soap decrease the frequency of childhood diarrhoea (Mintz et al. 2001; Curtis & Cairncross 2003). Recent meta-analyses estimate a mean 47% reduction in diarrhoea with hand washing with soap and a mean 35% reduction with point of use water treatment (Curtis & Cairncross 2003; Fewtrell et al. 2005). If either of these interventions was actively promoted by a public health organisation, the marginal cost of promoting the second one would be reduced. However, we are unaware of any studies evaluating the combined effectiveness of hand washing promotion with point-of-use water treatment.
In Pakistan, diarrhoea is a leading cause of death, especially in the squatter settlements of its large cities (Marsh et al. 1995; Khan et al. 1993). Previous intervention studies in squatter settlements in Pakistan have demonstrated that both point-of-use drinking water treatment with sodium hypochlorite and hand washing with soap reduced diarrhoea (Luby et al. 2004a, b). We introduced a new flocculent-disinfectant for home water treatment as part of a neighbourhood-based intervention. We evaluated its effect in reducing diarrhoea and the added effect of including hand washing promotion with soap.
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Among 6962 households in the study neighbourhoods, 1337 households (19%) met the inclusion criteria and enrolled in the study. The number of clusters, households, persons and births was similar across the intervention groups (Figure 1). Overall, data were collected from 92% of the potential person-weeks of follow-up, though it differed across groups, ranging from 87% among persons living in households that received flocculent-disinfectant to 96% in control households.
At baseline, the households in the different study groups were similar in size, socio-economic status, drinking water source, hand washing and sanitary facilities, and purchases of soap and water (Table 1). During the course of the study, children were routinely breastfed in all of the groups, although there was some difference by intervention group in exclusive breast-feeding among children under age 6 months.
Table 1. Characteristics of households by intervention group, Karachi Flocculent Health Study, Karachi, Pakistan, 2003
| ||Bleach water treatment (n = 252)||Soap and hand washing promotion (n = 262)||Flocculent-Disinfectant water treatment (n = 261)||Flocculent-Disinfectant plus Soap (n = 266)|| Control (n = 282)|
| Persons per household||9.4||9.2||10.1||9.3||8.8|
| Children <5 years of age per household||1.7||1.7||1.8||1.8||1.8|
| Children <2 years of age per household||0.57||0.52||0.61||0.64||0.60|
| Rooms in house||2.1||2.1||2.0||1.9||2.1|
| US$ spent on water in a normal week||0.60||0.52||0.52||0.60||0.50|
| Bars of hand soap purchased in preceding 2 weeks||1.1||1.2||1.2||1.2||1.2|
| Mother of the youngest child is literate||35||32||30||30||37|
| Mother of the youngest child finished secondary school||10||10||9||10||10|
| Monthly household income <54 US$||51||51||51||56||56|
| Salaried employee||56||50||56||55||50|
| Works for daily wages||38||40||39||38||42|
|Primary drinking water source|
| Municipal supply within the house||30||28||37||28||33|
| Municipal supply at a community tap||29||42||36||38||37|
| Tanker truck||18||15||12||14||12|
| Water bearer||13||11||10||10||13|
| Tube well||10||4||5||10||5|
| Re-supply household drinking water less frequently than once a day||37||39||39||32||37|
| Toilet without flush tank in the home||98||95||96||98||96|
| Place to wash hands with soap seen by study workers||24||22||23||21||24|
| Feces visible where children have access||8||9||12||12||11|
| Kitchen judged by field worker to be dirty or very dirty||43||49||45||44||44|
| % of person-weeks children <1 year were breastfed (n = 9527)||99||100||98||99||99|
| % of person-weeks children <1 year were exclusively breastfed (n = 9454)||12||22||16||17||13|
| % of person-weeks children <6 months were exclusively breastfed (n = 3012)||33||55||42||46||30|
Persons living in neighbourhoods that received any of the interventions had markedly less diarrhoea compared to persons living in control neighbourhoods (Table 2). The reduction in daily longitudinal prevalence of diarrhoea ranged from 51% among households receiving soap and hand washing promotion to 64% among households receiving flocculent-disinfectant. There was no apparent additional benefit to flocculent-disinfectant water treatment plus hand washing promotion with soap, compared to either of these interventions individually.
Table 2. Primary diarrhoea outcomes by intervention group, Karachi 2003
|Intervention group (person-weeks at risk)||Diarrhoea daily longitudinal prevalence (306 069)||Diarrhoea weekly longitudinal prevalence (306 069)|
|Mean† prevalence‡||Difference from control (95% CI)§||Mean‡ prevalence¶||Difference from control (95% CI)|
|Bleach water treatment||2.36||−55% (−17%, −80%)||4.07||−53% (−22%, −75%)|
|Soap and hand washing promotion||2.57||−51% (−12%, −76%)||4.73||−45% (−12%, −68%)|
|Flocculent-disinfectant water treatment||1.87||−64% (−29%, −90%)||3.51||−59% (−29%, −82%)|
|Flocculent-disinfectant plus soap||2.36||−55% (−18%, −80%)||4.34||−50% (−18%, −72%)|
The longitudinal prevalence of diarrhoea varied markedly over the course of the study. In July 2003, 190 mm of rain fell in Karachi, 2.6 times the 50-year mean July rainfall of 72 mm (U.S. Department of Commerce 2003). In the first 3 months of observation, persons living in neighbourhoods that received flocculent-disinfectant had a lower prevalence of diarrhoea compared to households that received soap and hand washing promotion or soap and hand washing promotion plus flocculent-disinfectant (Figure 2). During the heavy rains in July, the prevalence of diarrhoea in intervention neighbourhoods was the same as in control neighbourhoods. Diarrhoea prevalence peaked in the control group following the heavy July rains. During the last 5 months of observation the diarrhoea prevalence across the intervention groups tracked fairly closely together, and was markedly lower than control neighbourhoods.
Younger children had a higher longitudinal prevalence of diarrhoea, with infants having the highest prevalence (Table 3). The largest reductions in diarrhoea prevalence with interventions occurred among children 5–15 years. Diarrhoea prevalence was consistently lower among infants and children ≥1–2 years who lived in intervention neighbourhoods compared to control neighbourhoods, however the magnitude of the reductions were less than the overall reduction, and many of the individual age and intervention specific reductions were not statistically significant (Table 3).
Table 3. Longitudinal prevalence of diarrhoea by age group and intervention group, Karachi, 2003
|Age groups (observed person-weeks) (persons)||<1 year (11 930) 575||≥1−2 years (12 867) 663||≥2−5 years (55 475) 1824||≥5−15 years (158 107) 4719||>15 years (67 690) 2002|
|Diarrhoea prevalence (%)||Difference from control (95% CI)†||Diarrhoea prevalence (%)||Difference from control (95% CI)||Diarrhoea prevalence (%)||Difference from control (95% CI)||Diarrhoea prevalence (%)||Difference from control (95% CI)||Diarrhoea prevalence (%)||Difference from control (95% CI)|
|Bleach water treatment||8.30||−20% (14%, −48%)||6.02||−32% (0%,−57%)||4.15||−46% (−14%, −69%)||1.66||−67% (−20%, −98%)||0.79||−55% (32%, −97%)|
|Soap and hand washing promotion||7.86||−24% (6%, −48%)||6.36||−28% (6%, −55%)||4.63||−40% (−5%, −64%)||1.91||−62% (−11%, −95%)||0.79||−55% (31%, −98%)|
|Flocculent-disinfectant water treatment||6.20||−40% (−15%, −60%)||5.96||−32% (2%, −60%)||3.01||−61% (−32%, −83%)||1.36||−73% (−26%, −100%)||0.60||−66% (13%, −100%)|
|Flocculent-disinfectant plus Soap||6.48||−38% (−15%, −55%)||5.80||−34% (−6%, −56%)||3.94||−49% (−17%, −71%)||1.85||−63% (−13%, −95%)||0.78||−56% (30%, −97%)|
|Control||10.38|| ||8.82|| ||7.67|| ||5.06|| ||1.75|| |
Persons living in intervention neighbourhoods were significantly less likely to visit a practitioner for diarrhoea treatment (Table 4). Hospitalisation for diarrhoea was a rare outcome that did not occur at significantly different rates in intervention versus control neighbourhoods (Table 4). Intervention neighbourhoods had a substantially lower proportion of children under age 5 years with >10% of observed days with diarrhoea than persons in control neighbourhoods, though the 95% confidence limit in the bleach water treatment group did not quite exclude zero (Table 4).
Table 4. Severe diarrhoea outcomes by intervention group, Karachi 2003
|Intervention group (Child−weeks at risk)|| Saw a practitioner for diarrhoea (306 069)|| Hospitalised for diarrhoea (305 966)||Proportion of children <5 years with longitudinal prevalence of diarrhoea >10% (2273 children‡)|
|Proportion* of person-weeks (%)||Percent difference versus control (95% CI)†||Proportion of person-weeks (%)||Percent difference versus control (95% CI)|| Proportion§||Percent difference versus control (95% CI)|
|Bleach water treatment||3.8||−54% (−22%, −77%)||0.015||−39% (106%, −100%)||19.3||−44% (2%, −75%)|
|Soap and hand washing promotion||4.3||−48% (−15%, −71%)||0.020||−17% (157%, −86%)||15.6||−55% (−14%, −83%)|
|Flocculent-disinfectant water treatment||3.2||−61% (−31%, −84%)||0.018||−24% (134%, −84%)||10.4||−70% (−35%, −96%)|
|Flocculent-disinfectant plus soap||3.8||−55% (−23%, −77%)||0.038.||56% (347%, −32%)||13.0||−62% (−25%, −89%)|
The percentage of study participants followed up each week declined during the course of the study (Figure 3). This decline was most marked among persons living in neighbourhoods assigned to flocculent-disinfectant and least common among households in the control and hand washing promotion neighbourhoods. Excluding children born during the study, 82% of study subjects completed 34 (92%) or more weeks of follow-up. During the weeks they were observed, study subjects with fewer than 34 weeks of follow-up reported a similar mean longitudinal prevalence of diarrhoea compared to the mean longitudinal prevalence of study subjects in their same study group who completed 34 or more weeks of follow-up (Table 5).
Table 5. Characteristics of study subjects with above and below average follow-up*
| ||Follow up >33 person-weeks (n = 7313)||Follow up ≤33 person-weeks (n = 1636)|
|Mean age (years)||12.3||11.9|
|Mean diarrhoea longitudinal prevalence||2.9%||2.5%|
|Mean diarrhoea longitudinal prevalence by age at study initiation|
| <1 year||8.2%||6.2%|
| ≥1–2 years||6.7%||5.8%|
| ≥2–5 years||4.7%||3.8%|
| ≥5–15 years||2.3%||2.0%|
| ≥15 years||1.0%||0.7%|
|Mean diarrhoea longitudinal prevalence by study group|
| Bleach water treatment||2.4%||2.6%|
| Soap and hand washing promotion||2.6%||2.2%|
| Flocculent-disinfectant water treatment||1.9%||1.9%|
| Flocculent-disinfectant plus soap||2.2%||2.1%|
There was some reported difference in exclusive breastfeeding across intervention groups, especially among children under the age of 6 months (Table 1). However, children under the age of 6 months represent less than 1% of the total person-weeks observed, and the effects of the interventions were clearly independent of exclusive breast-feeding for the majority of the population who was beyond the age of breastfeeding (Table 3).
Households in the flocculent-disinfectant water treatment group averaged using 21.6 sachets per week or 4.4 l of treated water per person per day. Households in the flocculent-disinfectant plus hand-washing group averaged 20.4 sachets or 4.3 l of treated water per person per day. The consumption of sachets during July when there were heavy rains (21.5 sachets per household per week) was consistent with consumption throughout the summer. Households receiving bleach consumed sufficient bleach to treat an average of 3.0 l of treated water per person per day. Soap households averaged consuming 2.5 bars of soap per week, for a mean 3.5 g of soap per person per day.
Households often added ice purchased in the market to their drinking water. Between July and October households receiving the bleach water treatment added ice 5.3 times per week, households receiving the flocculent disinfected added ice an average of 5.2 times per week and households receiving the flocculent disinfected plus soap added ice an average of 4.9 times per week.
For the primary study outcome, the longitudinal prevalence of diarrhoea, the intracluster correlation coefficient was 0.105. The design effect was 21.1.
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Point-of-use water treatment with either bleach or flocculent-disinfectant as well as hand washing promotion with soap resulted in marked reductions in the overall prevalence of diarrhoea. The magnitude of the reduction in diarrhoea seen with hand washing promotion with soap and with dilute sodium hypochlorite was consistent with previous evaluations (Mintz et al. 2001; Curtis & Cairncross 2003; Luby et al. 2004a,b; Fewtrell et al. 2005). The 64% reduction in diarrhoea seen with flocculent-disinfectant was larger than the reductions noted in three previous trials in rural non-refugee settings including a 24%–29% reduction in an initial study in rural Guatemala (Reller et al. 2003), a 40% reduction in a follow-up study in rural Guatemala (Chiller et al. 2006) and a 16% reduction in rural Western Kenya (Crump et al. 2005). The most salient difference among these studies was that in Karachi, product consumption was substantially higher with a mean of over 20 sachets used per household per week compared to six in the first Guatemala study, 10 in the second Guatemala study and 10 in the Kenya study (Reller et al. 2003; Crump et al. in press; Chiller et al. in press).
The combination of household water treatment plus hand washing promotion with soap failed to reduce diarrhoea more than either intervention separately. Although this is the first simultaneous comparison of combined hand washing and water treatment compared against either intervention alone that we are aware of, in Fewtrell's meta analysis (2005) interventions that combined water, hygiene and sanitation interventions were no more effective in reducing diarrhoea than programs interventions that focused on a single intervention. One possible explanation is that 65%–75% of diarrhoea among persons living in this sewage contaminated environment is caused by pathogens that require a large dose to cause disease. A substantial reduction in the number of organisms ingested, either through hand washing or water treatment, may markedly reduce diarrhoea, but once ingested dose is below a certain threshold, further modest reduction in the dose of ingested organisms may not markedly reduce disease risk. Other possible explanations include that a substantial part of the reported reduction in diarrhoeal disease was a result of courtesy bias. Intervention households were given supplies free of cost, and may have wanted to meet the expectation of the study workers. Courtesy bias would not be expected to be additive with more interventions. A third possible explanation is that improving one hygiene behaviour in the home may lead to improvement in other hygiene related behaviours. Study workers provided supplies and messages only for the assigned intervention, but in descriptive studies hygiene behaviours are typically closely associated (Bartlett et al. 1992). Self-efficacy in one area could lead to self-efficacy in another. Fourth, it is possible that the combination of water treatment and hand washing promotion would have an additive effect, but introducing two interventions simultaneously did not allow their optimal combined use. Behaviour change is best achieved with single simple messages (Loevinsohn 1990), an approach that combining two interventions in one season did not permit. However, product consumption was similar in the combined and separate intervention arms.
Prior studies in squatter settlements in Karachi have noted a delay between distribution of household interventions and effect on diarrhoea outcome (Luby et al. 2004a,b). We hypothesize that with time there is technical mastery and increasingly habitual use of household interventions to prevent diarrhoea. During the present study after 6 weeks of intervention, the disease experience of the intervention neighbourhoods had diverged from the control neighbourhoods. However, none of the interventions appeared to be effective in preventing diarrhoea during the heavy rain and acute flooding in July. There was no fall off in product consumption during these weeks. This suggests that during the heavy rains and flooding there was so much fecal contamination of the environment that neither water treatment nor hand washing with soap reduced the ingested dose of pathogens sufficiently to prevent diarrhoea. After the flooding abated, the difference between intervention and control neighbourhoods re-emerged and was stable into the lower prevalence winter season as has been noted in a prior hand washing intervention study (Luby et al. 2004b).
Although intervention supplies were provided at no cost, fewer households were available for follow-up for each of the intervention groups compared to control. The largest drop off in use was among households using the most time-intensive intervention, the flocculent-disinfectant. For any of these household-based interventions to have a substantial public health impact they need to be valued enough so that a large proportion of the at-risk population chooses to become regular users.
There are important limitations to the study. First, study personnel and participants were not blinded to the intervention. It is possible that study participants in the intervention groups, grateful for the supplies, minimized reported episodes of diarrhoea in the household, or field workers recorded fewer episodes because of a desire to meet the expectation of study sponsors. However, field workers were formally trained, and the importance of accurate recording of reported symptoms was stressed. Unannounced supervisory visits did not identify systematic errors.
A second limitation is that the differential follow-up among groups suggests that persons who used the interventions more conscientiously may have been over-sampled compared to less regular users. However, the prevalence of diarrhoea did not differ among persons who were followed for fewer weeks, so their loss to follow-up is unlikely to have had a marked effect on the results.
In this setting where diarrhoea is a leading cause of death and the environment is heavily contaminated with sewage, household-level interventions to improve drinking water quality and hand washing promotion with soap resulted in a marked reduction in diarrhoea. Outside of a randomised controlled trial, in which participants were provided supplies at no cost and regularly encouraged to use them, water treatment and hand washing would probably be less consistent. Some families and individuals may be more inclined to adopt one or the other intervention. Thus, as part of a public health program, promoting both hand washing and point-of-use water treatment with safe storage may expand the proportion of the population that adopts a protective behaviour and thereby produce additive benefit. However, these data suggest that an additive benefit of hand washing and water treatment should not be assumed, that the cost of multiple messages both for public health programs to deliver and for low income families to adopt may not be justified. The next step in determining the role that these approaches have in preventing diarrhoea globally is to implement them at larger scale and evaluate their practicality, uptake and effectiveness.
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We thank the HOPE staff workers who worked in the community, Aqil Hussain, Gharnata Tabassum, Zahida Kanum, Badar and Sabeen who supervised the daily field work and data collection, Faisal Sarwari and Asif Ahmed who supervised data entry, Will Duck who programmed the initial Access database, and Eben Kenah who assisted in calculation and interpretation of the intracluster correlation coefficient. The majority of the funding for this study was provided by the Procter & Gamble Company, the manufacturer of Safeguard Bar Soap® and PuR®. The balance of the funding was provided by the Centers for Disease Control and Prevention.