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ABSTRACT This population-based epidemiologic study investigated the associations of individuals’ sociodemographic statuses, sanitary systems and habits, water supply and drainage conditions with diarrhoea incidences among 707 children younger than 5 years who were living in slum communities with various water logging patterns in Dhaka, Bangladesh. We conducted a homevisiting survey during the pre-monsoon period from December 2006 to April 2007. Nine slum communities were selected that had been experiencing five different water logging conditions. One non-water logging community was selected as a control. The Disability Adjusted Life Years (DALYs) were calculated using data on diarrhoea morbidity and mortality. Although DALYs lost because of diarrhoea were very small in a non-inundation type community, but were the highest in persistent drainage inundation type communities. Among the factors correlated with DALYs, control variables for mother’s illiteracy and household income strongly attenuated most of these correlations to statistical null, except for mother’s age (less than 15 years-old), using hanging latrine and not washing hands before eating, and after defecation. In conclusion, water logging conditions and socio-economic statuses may strongly contribute to diarrhoea incidence in the city’s slum communities. In such communities, interventions to address both water logging and socio-economic conditions may be critical for reducing diarrhoea incidences.
Journal of Water and Environment Technology, Vol 7, No 4, 2009 Children’s Health Deficits due to Diarrhoea: Effects of Water Supply and Sanitation Systems in Slums with Different Water Logging Conditions Kabirul Ahsan MOLLAH*, Kei NISHIDA*, Naoki KONDO* and Zentaro YAMAGATA* * Interdisciplinary Graduate School of Medicine and Engineering, the University of Yamanashi 4-3-11, Takeda, Kofu, Yamanashi 400-8511, Japan ABSTRACT This population-based epidemiologic study investigated the associations of individuals’ sociodemographic statuses, sanitary systems and habits, water supply and drainage conditions with diarrhoea incidences among 707 children younger than years who were living in slum communities with various water logging patterns in Dhaka, Bangladesh We conducted a homevisiting survey during the pre-monsoon period from December 2006 to April 2007 Nine slum communities were selected that had been experiencing five different water logging conditions One non-water logging community was selected as a control The Disability Adjusted Life Years (DALYs) were calculated using data on diarrhoea morbidity and mortality Although DALYs lost because of diarrhoea were very small in a non-inundation type community, but were the highest in persistent drainage inundation type communities Among the factors correlated with DALYs, control variables for mother’s illiteracy and household income strongly attenuated most of these correlations to statistical null, except for mother’s age (less than 15 years-old), using hanging latrine and not washing hands before eating, and after defecation In conclusion, water logging conditions and socio-economic statuses may strongly contribute to diarrhoea incidence in the city’s slum communities In such communities, interventions to address both water logging and socio-economic conditions may be critical for reducing diarrhoea incidences Keywords: DALY, diarrhoea, poor urban community, water logging INTRODUCTION Poor environmental sanitation and the unsafe disposal of human and solid wastes contribute to the high incidence of water-borne diseases, including diarrhoeal diseases, malaria and dengue fever (WHO/UNICEF 2001) Many of these infections occur in developing nations that have sanitation problems (Nsubuga et al 2004) In these nations, most low-lying lands used for squatter settlements or slums have hanging latrines or open-field defecation Due to lack of access to potable water supplies, the poor rely mainly on shallow wells, rivers, streams and ponds for daily water needs (Nevondo and Cloete 1999) In most cases, water from these sources, which may be faecally contaminated, is used directly without treatment (WHO 1993) During 2002, it was estimated that 4% (60.7 million Disability Adjusted Life Years [DALYs]) of the global burden of disease and 1.6 million deaths per year were attributed to unsafe water supplies and sanitation, including lack of hygiene (WHO 2002) Acute diarrhoeal diseases are the major causes of morbidity and mortality in developing countries, such as Bangladesh, where in 10 children die before their fifth birthday (Bern et al 1992; Petri et al 2000) Bangladesh’s capital city, Dhaka, is a typical floodprone urban habitat It is periodically devastated by floods, resulting in stagnant water and drainage problems (JICA 1990; JICA 1987; SWMC 1997) The inadequate Address correspondence to Kei NISHIDA, Interdisciplinary Graduate School of Medicine and Engineering, the University of Yamanashi, Email: nishida@yamanashi.ac.jp Received June 18, 2009, Accepted August 27, 2009 - 277 - Journal of Water and Environment Technology, Vol 7, No 4, 2009 drainage in nearly 60% of slums assures that many slums are at risk of flooding (CUS et al 2006), faecal contamination (Fawell 2007) and consequent cases of diarrhoea, whereas childhood diarrhoea is not prevalent in areas with higher elevations (Brussow 1993) Inavailability of sanitary facilities also contributes Among slums in Dhaka, only over 35% of households use hygienic latrines, whereas, for garbage management, 35% just use vacant land and water bodies as waste disposal sites This neglected population in slums has become a major reservoir for a wide spectrum of adverse health conditions, including most prevalent diarrhoeal diseases, intestinal problems, fever and skin diseases (Rahman et al 1989; Hussain et al 1999;Rahman and Shahidullah 2001; Sclar et al 2005), and has a high infant mortality rate (Hoque and Selwyn 1996; Arifeen et al 2001) Consequently, urban slum dwellers have been identified as a particularly vulnerable group regarding health status by Bangladesh’s Poverty Reduction Strategy Planning (PRSP) of the Government of Bangladesh, 2005 In 2000, the United Nations Millennium Declaration pledged to tackle this challenge by setting specific goals and attempting to achieve significant improvements in the lives of at least 100 million slum dwellers worldwide by the year 2020 (UN 2007; Riley 2007) In light of these worldwide phenomena, the government of Bangladesh is also committed to achieving the targets embodied in the UN Millennium Declaration by 2015 (World Bank 2006a, 2007) Thus, demonstrating the impact of water logging on diarrhoeal incidence in Dhaka City, and how household and individual factors interact with this impact are of utmost necessity in finding prime locations for slum development programmes The objectives of this study are: (1) to estimate variations in children’s diarrhoea incidence among Bangladesh’s urban slum communities based on their inundation conditions, and (2) to assess the populations’ demographic factors, socioeconomic status, sanitary facilities and attitudes as potential factors associated with diarrhoea incidence among slums with varying flood and inundation conditions METHODS Study population Based on flood and inundation experience, slum communities in Dhaka were selected from different representative water logging situations categorized in terms of duration and type of inundation We proposed levels based on duration of inundation (shortterm, long-term, persistent and non-inundation) and types of inundation (rainy, stagnant-water, heavy-rainy, monsoon-flood and drainage-water inundations) Ten subdistricts were selected by integrating information regarding water logging for the past 5–10 years that was obtained from interviews with the concerned authorities and dwellers as well as on-site measurements from a preliminary survey conducted in December 2006 The slum communities selected were situated within km from the Urban Development Centre project offices of the Slum Development Department of the Dhaka City Corporation (Table and Figure 1) Thus, for the ‘code name’, we used the initials of inundation duration, inundation type and the respective sub-district name of - 278 - Journal of Water and Environment Technology, Vol 7, No 4, 2009 each studied community; the code name will be used for the following discussion as corresponding to each community Table - Inundation categories and code names of studied slum communities Sub-districts Duration based Short-term Long-term Persistent None Ward Mirpur Uttara Gulshan Demra Tejgaon Khilkhet Lalbagh Sabujbagh Muhammadpur Jatrabari-Dhalpur Inundation category 15 19 86 37 17 65 27 47 29 Code name Type based Rainy Heavy-rainy Drainage-water Stagnant-water Heavy-rainy Monsoon-flood Drainage-water Heavy-rainy Stagnant-water None SRM SHU SDG LSD LHT LMK PDL PHS PSM NCD A household was defined as people sharing the same cooking pot (Hussain et al 1999) Using this definition, 820 households in 10 sub-districts were identified during the preliminary survey Of the 350 households satisfying the predefined criteria (35 households from each community), presence of children less than years of age, water supply and no improvement in sanitation (WHO/UNICEF 2003; WHO/UNICEF JMP 2000) were selected for additional questionnaire surveys Informed consent was obtained from the parents or guardians N • SHU • LMK • SRM • SDG • LHT • PSM • NCD • PHS • PDL • LSD Sub district boundaries Canals Embankment River DHAKA CITY 1 0 1 2 km Fig - Study site map in Dhaka, Bangladesh; adapted by authors (Source: http://www.en.wikipedia.org) - 279 - Journal of Water and Environment Technology, Vol 7, No 4, 2009 Diarrhoea incidence and questionnaire Among water-borne diseases, diarrhoea is a condition of morbidity that is relatively easy to monitor- as it occurs rather frequently Respondent mothers easily understand its definition, and there is little variation of symptoms from mothers’ perceptions (Killewo and Smet 1989): the occurrence of or more loose, watery or mucous stools in the previous 24 h (WHO 2009) We followed the definition of acute diarrhoea by the World Health Organization (WHO) and UNICEF: an attack of sudden onset that usually lasts 3–7 days but may last up to 10–14 days (Park 1997) We used a period of intervening diarrhoea-free days to differentiate a new incidence of diarrhoea (Baqui et al 1991) The Child Health Epidemiology Reference Group of WHO (WHO/CHERG 2004) summarized a table for the definition of diarrhoeal deaths that was used in this survey for verbal autopsy, which has a very good agreement with hospital diagnosis (Kalter et al 1990; Pacque-Margolis et al 1990) In April 2007, investigators asked each mother to follow her child/children for weeks after recruitment, and during a preliminary visit, they described how to confirm the presence of diarrhoea They also demonstrated how to mark the day that symptoms first started and the day that the illness ended or the child succumbed to the illness The information was reported to investigators at the follow-up two weeks later The 2-week interval was chosen because diseases and symptoms assessed and reported by inhabitants can be imprecise; high reliability depends on shorter recall periods (Byass et al 1994) Final data were recorded only if the data were consistent with the mothers’ performance levels in defining the symptoms and counting the days of illness We developed a series of household-level questionnaires based on the World Bank (World Bank 1999), WHO (WHO 1991) and United Nations guidelines (UN 2005, 2001, 1998, 1984) These questionnaires had modified wording to improve suitability for the study population after pre-testing during a preliminary visit The interview survey requested information regarding hygiene practices, water supply and sanitation situations, household income, maternal educational attainment and demographic characteristics (Mollah et al 2009) Septic tanks and pour-flush latrines connected to a sewer line were considered as sanitary latrines for the purpose of this study Unsanitary types consisted of cesspools, pit latrines and storage tank facilities; open and homemade latrines consisted of hanging latrines Drainage pipes from latrines were usually connected to sewer lines, and human excreta were directly discharged without treatment Calculation of Disability Adjusted Life Years (DALY) Morbidity and mortality cases of diarrhoea for children less than years old and their significance were used to estimate DALYs in each community (Murray and Acharya 1997) DALYs combine years of life lost (YLL) with years lived with disability (YLD) These are standardized using severity weights (Murray et al 1996) and durations of morbidity (Murray et al 2002) DALYs, due to premature mortality, are calculated using standard expected YLL from model life tables and, due to disability from age a to age (a + L), consists of the following equation derived by Murray (1994) and Homedes (2000): - 280 - Journal of Water and Environment Technology, Vol 7, No 4, 2009 (Eq 1) Here, β is an age-weighting parameter, C is an age-weighting correction constant, r is a time preference discount rate, D represents stages of physical disability that consequently affected daily living activities (productive activities, for instance school or work), a is set on an age at which the child suffered a particular disease or died and L assumes value sets, YLD and YLL The DALY formula was established with a lost time concept of disability due to suffering from any specific disease, including fatality The value was estimated based on life expectancy in a developed country (e.g Japanese life expectancy for male and female) as well as an age-weighted lost time discounting value for the developed world, used for global DALY calculation Accordingly, we decided upon C (0.16243), β (0.04) and r (0.03) as the default values for a global context In contrast, applied available local data set for D = in case of death, 0.3, 0.5 in case of diarrhoea, a = 1, for each age group (assumed from the interview survey, average age of infant and child, respectively) and L, for morbidity calculation, YLD = 0.21, 0.28, 0.36, 0.43 (assumed from the interview survey) and, for mortality calculation, YLL = 62 years for male and 63 years for females in Bangladesh as of 2005 (WHO 2007) Furthermore, the default values for β, C and r have no influence for the age group younger than 15, considered as work force, which sets the priority for the time lost at this age For D, its influence depends on each subject’s degree of end point (range 0–1) This requires quantitative and qualitative estimations to define the value of D, a technical task for this study as well The value for L also influences a greater variation for cases with very low life expectancy, whereas for a, its influences are lower and higher at a cut-off age of 20 The team physician assessed the degree of dehydration according to the WHO criteria (WHO 1990) The severity of each diarrhoeal disease incidence was calculated using a numerical scoring system (Ruuska et al 1990), which we modified into classes Accordingly, in our study, D is decided with numerical values for adjusted morbidity days and scored for different severities, which also substantially reduced error on the value based only on qualitative estimation All of the above default values for β, C and r have an influence, but only for ages over years Thus, in our study, these imparted no influences, as our subjects were children less than years of age Statistical analyses After the DALY calculations by community types, we evaluated the factors that correlated with the DALYs lost among the 10 communities using Pearson correlation coefficient and multivariate partial correlation analyses All analyses used SPSS software version 15 (SPSS Inc., Chicago, USA, 2007) RESULTS AND DISCUSSION Forty percent of households had or more family members, and 40% of the studied households had monthly household incomes less than 30 USD Age less than 15 years - 281 - Journal of Water and Environment Technology, Vol 7, No 4, 2009 and illiteracy of respondent mothers were also higher (greater than 40%) in this survey, except for the non-inundated community (NCD), compared to the national average (BBS 2007) (Figure 2-a) In the NCD, tap water was used in 100% of households and 80% had sanitary latrines, whereas in other communities, only 23–54% used tap water and 0–9% had sanitary latrines (Figure 2-b and c) In particular, slums under persistent water logging conditions were likely to have worse sanitary conditions (i.e relatively higher rates of unsanitary hanging latrines or no latrine) (Figure 2-c) Almost 67% of households among the surveyed households did not practice any type of water treatment at home, while around 14% and 17% used only simple filtering with cloth or boiled water before drinking, respectively (Figure 2-d) We found that children’s open-field defecation occurred in 51% of all the communities, except for the NCD, where defecation in the open was not a common cultural feature For example, in the persistent and drainage-water type community (PDL), none of the children used latrines (Figure 2-e) There were remarkable differences for not washing hands among communities, both before eating and after defecation, which can be calculated from the Figure 2-f, with ranges of 17–47% and 18–85%, respectively Almost all communities showed a common tendency for washing hands before eating, but not washing hands after defecation, and PDL had a remarkably high rate of not washing hands after defecation (Figure 2-f) On average, diarrhoea was the most common disease in the study subjects Half of them suffered from diarrhoea during the week observation period, while the combined cumulative incidence of other diseases, including fever, pneumonia, jaundice, tonsillitis and skin disease, was far below that of diarrhoea However, diarrhoea incidence varied greatly across communities, and PDL had the highest rate (Table 2) There were no significant variations in days of illness on a per case basis or for frequency of incidences in each community We calculated the average frequency of diarrhoeal incidences from cumulative incidences by dividing by the number of sick children during two weeks in the respective communities Children living in locations with stagnant and drainage water problems had comparatively higher suffering days (range 5–6 days) and frequency of diarrhoeal illness incidences (at least twice) (Figure 3) Here we calculated the frequency as a rate of incidences per sick child and average of these rates in a corresponding community were used for comparison among communities The DALYs lost were 173–843-fold higher in the inundated locations compared to those in the noninundated locations (Table 2) Among the inundation categories, differentials of DALYs lost were larger for the short-term compared to the long-term (1.27-fold higher, on average), and for the long-term compared with the persistent (1.45-fold higher, on average) - 282 - Journal of Water and Environment Technology, Vol 7, No 4, 2009 ( a) 70 100 60 50 40 30 20 10 SRM SHU SDG LSD LHT LMK PDL PHS PSM NCD Households in each community ( % ) Households in each community ( % ) 80 (d) 90 80 70 60 50 40 30 20 10 SRM SHU Family members ≥7 Familymembers ≥7 Girls aged