Deep Tubewells Provide Protection Against Childhood Diarrhea in Matlab, Bangladesh

Jennifer Winston, Veronica Escamilla, Carolina Perez-Heydrich, Margaret

Carrel, Mohammad Yunus, Peter Kim Streatfield, Michael Emch

IntroductionThis study investigates whether deep tubewells installed for arsenic mitigation in rural Bangladesh also protect children from diarrheal diseases.

Background1970s and 1980s: government

and NGO community installed millions of shallow tubewells (<140 ft) throughout Bangladesh.

Led to nearly universal shift from drinking surface water to groundwater.

Coupled with improved hygiene and sanitation, tubewell use may have contributed to overall decline in diarrhea induced deaths observed in Bangladesh.

BackgroundIn 1990s, naturally occurring arsenic found in shallow

tubewells, at levels exceeding the WHO and Government of Bangladesh drinking water standards.

About half of the country’s population was exposed to levels exceeding the WHO standard.By 2000, the Bulletin of the WHO had declared a "public health emergency."

Prolonged exposure can lead to health problems ranging from skin problems to cancer.

Photo: SOS arsenic

BackgroundNearly 5 million wells were tested for

arsenic.Tubewells exceeding the Bangladesh

arsenic standard were painted red.Safe wells were painted green.

Since 2000, an estimated 165,000 deep tubewells have been installed (usually more than 500 feet deep).Usually public, due to high installation

costs. Often located near a rural road or

walking path where villagers will have easy access.

Photo: Yubanet.com

BackgroundMitigation responses by

Bangladeshis:1. switch from a shallow high

arsenic well to the nearest shallow low arsenic well. May expose users to higher

levels of fecal contamination(?)

2. obtain drinking water from a deep tubewell tapping into an aquifer usually more than 500 feet deep.

Study setting and dataMatlab, a rural region in

Bangladesh, where households clustered in baris (5,279 in this study).

Field site for the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b). Community level childhood

diarrheal disease survey (2005-2006)

Health and demographic surveillance system (since 1966), maintains records of all residents. In 2005, collected SES data.

Study setting and dataSurvey of Matlab’s 12,018

tubewells (2002-2004). Locations recorded using global

positioning system receivers. Information on tubewell depth

gathered from well owners, who generally know the length of PVC pipe used to install the well.

Supplemented by a 2009 survey asking people to identify any deep community tubewell in or adjacent to their bari.

Photo: icddr,b

MethodsMade assumptions about deep and shallow tubewell use:

Measured distance from each bari to the nearest deep tubewell in GIS.

Defined deep and shallow tubewell use according to the following assumptions:

MethodsTested the accuracy of assumptions about tubewell use by

building a logistic regression model to predict surveyed deep tubewell use in a six village sub-sample. Deep tubewell use was correctly classified for 76% of the time.

Longitudinal logistic regression model Outcome of interest: binary variable of occurrence of

childhood diarrhea within the year. Main predictor of interest: binary variable for deep tubewell

use. Covariates: Wealth index, maternal education, population of

children under 5, and year.

ResultsOverall, the distribution of counts of childhood diarrhea was found to be wider and more variable for shallow tubewell users than for deep tubewell users.

Results, continuedParameter OR 95% CI

Deep tubewell use 0.513 0.365 – 0.722

Population < 5 yrs 1.095 1.076 – 1.111

Maternal education 0.965 0.931 – 1.000

Wealth Index 0.963 0.876 – 1.059

Distance to nearest deep tubewell 1.000 0.999 – 1.000

Year 0.817 0.753 – 0.886

Distance: Use 1.002 0.998 – 1.006

LimitationsAssumption regarding deep tubewell use.

Correctly classified 76% of baris in sub-sample with known tubewell use

Sensitivity analysis: 1. Randomly selected 25% of sample baris and re-classified

deep tubewell use.2. Re-ran analysis using reclassified use variable. 3. Results were consistent with those obtained using the

original data. Protective effect of deep tube well use was lower (OR: 0.789, 95% CI: 0.642 - 0.971), though still significantly below 1.0.

ConclusionsDeep tubewells seem to have a protective effect against childhood

diarrhea incidence. At least within 150 meters, distance does not seem to have an effect

on childhood diarrheal disease incidence amongst users of deep tubewells.

Further development of the deep tubewell infrastructure in rural Bangladesh requires several considerations: Deep tubewells are expensive, so government and NGO’s need to be

involved.Community training on deep tubewell maintenance is also needed to

avoid unsafe practices. The sustainability of deep groundwater quality must also be considered.

Acknowledgements International Centre for Diarrheal Disease Research, Bangladesh (ICDDR,B) and

its core donors: the Australian International Development Agency, the government of the People’s Republic of Bangladesh, the Canadian International Development Agency, the Swedish International Development Cooperative Agency, and the Department for International Development, UK.

National Institutes of Health (grant NIH R03-AI076748) and (grant NIH 5 T32AI07001-36)

National Institute of Environmental Health Sciences (grant NIEHS T32ES007018)National Science Foundation (grant NSF BCS-0924479). Eunice Kennedy Shriver National Institute of Child Health and Human

Development (NICHD)5 R24 HD050924 and 5 T32 HD007168.