Burden of disease from inadequate water, sanitation and hygiene in low- and middle-income settings: a retrospective analysis of data from 145 countries. Trop Med Intl Health, in press, 2014.
Objective - To estimate the burden of diarrhoeal diseases from exposure to inadequate water, sanitation and hand hygiene in low- and middle-income settings and provide an overview of the impact on other diseases.
Methods - For estimating the impact of water, sanitation and hygiene on diarrhoea, we selected exposure levels with both sufficient global exposure data and a matching exposure-risk relationship. Global exposure data were estimated for the year 2012, and risk estimates were taken from the most recent systematic analyses. We estimated attributable deaths and disability-adjusted life years (DALYs) by country, age and sex for inadequate water, sanitation and hand hygiene separately, and as a cluster of risk factors. Uncertainty estimates were computed on the basis of uncertainty surrounding exposure estimates and relative risks.
Results - In 2012, 502 000 diarrhoea deaths were estimated to be caused by inadequate drinking water and 280 000 deaths by inadequate sanitation. The most likely estimate of disease burden from inadequate hand hygiene amounts to 297 000 deaths. In total, 842 000 million diarrhoea deaths are estimated to be caused by this cluster of risk factors, which amounts to 1.5% of the total disease burden and 58% of diarrhoeal diseases. In children under 5 years old, 361 000 deaths could be prevented, representing 5.5% of deaths in that age group.
Conclusions - This estimate confirms the importance of improving water and sanitation in low- and middle-income settings for the prevention of diarrhoeal disease burden. It also underscores the need for better data on exposure and risk reductions that can be achieved with provision of reliable piped water, community sewage with treatment and hand hygiene.
Authors: Islam MS1, Ansaruzzaman M, Mahmud ZH, Matin MA, Islam MS, Mallik AK, Neogi SB, Jahid IK, Endtz HP, Cravioto A, Sack DA.
BACKGROUND: People in rural Bangladesh have a poor understanding of the link between use of contaminated surface water and disease. An inexpensive point-of-use water treatment agent was developed to purify surface water.
METHODS: Surface water was collected from various sources in Bangladesh from February 2007 to January 2008. Microbiological and physicochemical parameters of raw and treated surface water were analysed. Water was treated with a mixture of alum potash, bleaching powder and lime, or with each agent individually.
RESULTS: Raw water was contaminated with bacteria, the counts for total coliforms, faecal coliforms and faecal streptococci being 26 431, 14 548 and 240 colony-forming units (cfu) 100 ml(-1), respectively. These counts fell to 0 cfu 100 ml(-1) after treatment with the mixture. The count of artificially introduced Vibrio cholerae was also reduced to 0 cfu 100 ml(-1) after treatment. Treatment of raw water altered the pH from 6.90 to 6.87, turbidity from 21.61 to 3.55 nephelometric turbidity units (NTU), residual chlorine from 0 to 0.09 mg litre(-1), conductivity from 124.03 to 229.96 µS cm(-1), and total dissolved solids from 59.40 to 199.25 mg litre(-1). All these results of treatment were within the range recommended by the WHO as acceptable for drinking water.
CONCLUSION: The mixture of alum potash, bleaching powder and lime described can be safely used to disinfect contaminated surface water to make it suitable for drinking and other household purposes in Bangladesh.
The purpose of this research endeavor was to examine how various technical, geographical, and socioeconomic parameters affected biosand filter (BSF) performance in Sisit, Kenya. In 2010, Mercer students installed 25 BSFs throughout the village of Sisit. As part of the 2012 Mercer on Mission trip to Sisit, each previously installed filter’s performance parameters (flow rate, % coliform removal, etc.) were compared to respective distances, populations, and levels of affluence. Analysis illustrated that the distance between a household and the community center is highly correlated to various aspects of BSF performance. A relationship was also shown to exist between a BSF’s coliform removal efficiency and the distance between the associated household and water collection point.
Ask When–Not Just Whether–It’s a Risk: How Regional Context Influences Local Causes of Diarrheal Disease. Am J Epidemiol. 2014 Apr 15.
Authors: Goldstick JE, Trostle J, Eisenberg JN.
Contemporary epidemiology is enriched when it incorporates ecological concepts about systems and dependencies. With regard to diarrheal disease, the causes of which are many and interacting, the dynamics of within- and between-community disease transmission have distinct components but are also linked in important ways. However, few investigators have studied how regional-scale disease dynamics affect local patterns of diarrheal disease transmission. Characterizing this dependence is important for identifying local- and regional-level transmission pathways. We used data from active surveillance of diarrheal disease prevalence gathered from February 2004 through July 2007 in 21 neighboring Ecuadorian villages to estimate how disease prevalence in spatially and temporally proximate villages modulates the influences of village-level risk and protective factors.
We found that the impact of local, village-level interventions such as improved latrines and water treatment can be quite different under conditions of high and low regional disease prevalence. In particular, water treatment was effective only when regional disease prevalence was low, suggesting that person-to-person spread, not waterborne spread, is probably responsible for most between-village transmission in this region. Additional regional-scale data could enhance our understanding of how regional-scale transmission affects local-scale dynamics.
Association between Moderate-to-Severe Diarrhea in Young Children in the Global Enteric Multicenter Study (GEMS) and Types of Handwashing Materials Used by Caretakers in Mirzapur, Bangladesh. Am Jnl Trop Med Hyg, April 2014.
Abstract – Handwashing practices among caretakers of case and control children < 5 years of age enrolled in the Global Enteric Multicenter Study in Mirzapur, Bangladesh were characterized and analyzed for association with moderate-to-severe diarrhea. Soap or detergent ownership was common, yet 48% of case and 47.7% of control caretakers also kept ashes for handwashing, including 36.8% of the wealthiest households. Soap, detergent, and ash were used for multiple hygiene purposes and were kept together at handwashing areas.
Caretakers preferred soap for handwashing, but frequently relied on ash, or a detergent/ash mixture, as a low-cost alternative. The moderate-to-severe diarrhea was equally likely for children of caretakers who kept soap versus those who kept ash (median odds ratio [mOR] = 0.91; 0.62–1.32). Contact with ash and water reduced concentrations of bacterial enteropathogens, without mechanical scrubbing. Thus, washing hands with ash is a prevalent behavior in Mirzapur and may help diminish transmission of diarrheal pathogens to children.
Assessing the Impact of Water Filters and Improved Cook Stoves on Drinking Water Quality and Household Air Pollution: A Randomised Controlled Trial in Rwanda. PLoS One, March 2014.
Diarrhoea and respiratory infections remain the biggest killers of children under 5 years in developing countries. We conducted a 5-month household randomised controlled trial among 566 households in rural Rwanda to assess uptake, compliance and impact on environmental exposures of a combined intervention delivering high-performance water filters and improved stoves for free. Compliance was measured monthly by self-report and spot-check observations. Semi-continuous 24-h PM2.5 monitoring of the cooking area was conducted in a random subsample of 121 households to assess household air pollution, while samples of drinking water from all households were collected monthly to assess the levels of thermotolerant coliforms.
Adoption was generally high, with most householders reporting the filters as their primary source of drinking water and the intervention stoves as their primary cooking stove. However, some householders continued to drink untreated water and most continued to cook on traditional stoves. The intervention was associated with a 97.5% reduction in mean faecal indicator bacteria (Williams means 0.5 vs. 20.2 TTC/100 mL, p<0.001) and a median reduction of 48% of 24-h PM2.5 concentrations in the cooking area (p = 0.005). Further studies to increase compliance should be undertaken to better inform large-scale interventions.
Authors: Ayse Ercumen, Joshua S. Gruber, and John M. Colford Jr.
Background: Water distribution systems are vulnerable to performance deficiencies that can cause (re)contamination of treated water and plausibly lead to increased risk of gastrointestinal illness (GII) in consumers.
Objectives: It is well established that large system disruptions in piped water networks can cause GII outbreaks. We hypothesized that routine network problems can also contribute to background levels of waterborne illnessand conducted a systematic review and meta-analysis to assess the impact of distribution system deficiencies on endemic GII.
Methods: We reviewed published studies that compare direct tap water consumption to consumption of tap water re-treated at the point of use (POU) and studies of specific system deficiencies such as breach of physical or hydraulic pipe integrity and lack of disinfectant residual.
Results: In settings with network malfunction, consumers of tap versus POU-treated water had increased GII (incidence density ratio (IDR) = 1.34; 95% CI: 1.00, 1.79). The subset of non-blinded studies showed a significant association between GII and tap versus POU-treated water consumption (IDR = 1.52; 95% CI: 1.05, 2.20), but there was no association based on studies that blinded participants to their POU water treatment status (IDR = 0.98; 95% CI: 0.90, 1.08). Among studies focusing on specific network deficiencies, GII was associated with temporary water outages (relative risk = 3.26; 95% CI: 1.48, 7.19) as well as chronic outages in intermittently operated distribution systems (odds ratio = 1.61; 95% CI: 1.26, 2.07).
Conclusions: Tap water consumption is associated with GII in malfunctioning distribution networks. System deficiencies such as water outages also are associated with increased GII, suggesting a potential health risk for consumers served by piped water networks.
Authors: Luke Juran and Morgan C. MacDonaldDepartment of Geography and Virginia Water Resources Research Center, Virginia Tech, 125 Major Williams Hall, Blacksburg, VA 24061, USA E-mail: ljuran@vt.edu; lukejuran@yahoo.com. School of Engineering, University of Guelph, 3120 Thornbrough, Guelph, ON N1G 2W1, Canada
This article scrutinizes the boiling of water in Tamil Nadu and Puducherry, India. Boiling, as it is commonly practiced, improves water quality, but its full potential is not being realized. Thus, the objective is to refine the method in practice, promote acceptability, and foster the scalability of boiling and household water treatment (HWT) writ large. The study is based on bacteriological samples from 300 households and 80 public standposts, 14 focus group discussions (FGDs), and 74 household interviews. Collectively, the data fashion both an empirical and ethnographic understanding of boiling. The rate and efficacy of boiling, barriers to and caveats of its adoption, and recommendations for augmenting its practice are detailed. While boiling is scientifically proven to eliminate bacteria, data demonstrate that pragmatics inhibit their total destruction. Furthermore, data and the literature indicate that a range of cultural, economic, and ancillary health factors challenge the uptake of boiling. Fieldwork and resultant knowledge arrive at strategies for overcoming these impediments. The article concludes with recommendations for selecting, introducing, and scaling up HWT mechanisms. A place-based approach that can be sustained over the long-term is espoused, and prolonged exposure by the interveners coupled with meaningful participation of the target population is essential.
