kaida liang before i begin, i want to thank you for...

INDEPENDENT EVALUATION OF THE BIOSAND WATER FILTER IN

RURAL CAMBODIA: SUSTAINABILITY, HEALTH

IMPACT AND WATER QUALITY

Kaida Liang

Presenter

Presentation Notes

Before I begin, I want to thank you for coming Especially to my committee who came from the beach or the mountains for a Monday morning defense on diarrhea Please help yourself to food, coffee and juice and hunker down for the next few minutes together As you can see, the title of my presentation is……….

Background of BSF in Cambodia• Widespread lack of safe drinking

water– Microbiological and chemical

contamination – Rural households lack access

to a conventional water treatment system

• BSFs introduced (1999-pilot)– Hagar and Cambodia Global

Action (CGA) implementing BSF projects

– Supported by Samaritan’s Purse (SP) and the Canadian International Development Agency

Presenter

Presentation Notes

I would also like to provide you with some background of the BSF in Cambodia EXPLAIN THE PICTURE Cambodia has also become a locus for HWT and technologies, approximately 200,000 people are using either ceramic or bsfs

BSF projects

What has happened with the 20,000+

biosand filters introduced in Cambodia?

343982

Presenter

Presentation Notes

This map shows the number of Biosand filters installed by Hagar, a local NGO and largest implementor of the BSFs BSFs installed in almost all provinces however, the provinces included this study will be from Svay Rieng, Kompong Thom, and Kratie There is currently over 70,000 requests from across Cambodia for the BSF program.

Study Objectives

Assess the following parameters and indicators:

i. sustainability: continued use of previously installed filters over time

ii. water quality: microbiological effectiveness in situ of the filters still being used

iii. health impact: a prospective cohort study in which diarrheal disease incidence is measured among people in filter (intervention) households versus people in matched non-filter, control households

Household Enrollment

21 000 + Households

175 Randomly Selected CGA HouseholdsCGA

175 Randomly Selected Hagar Households

336 Households

51 CGA Intervention Households(2 households quit study)

53 Hagar Intervention Households(2 households quit study)

53 Hagar Control Households

51 CGAControl Households

Longitudinal Prospective Cohort Study

Cross Sectional Study

Presenter

Presentation Notes

Households were enrolled for the cross sectional survey from a master list of all filter recipients generated by the implementing organizations From the 21, 090 filters that were listed, 175 households were randomly selected from each organization and apportioned to ensure representation from each village, district, commune, province according to the number of filters in each location A total of 336 households participated in the cross sectional survey Households participating in the cross sectional survey met eligibility criteria: received a filter from one of the implementing organizations, living at original location where they received the filter, voluntary willingness to participate in the study and signed informed consent form From the 336 households, we recruited households for the longitudinal prospective cohort study 53 households from Hagar and 51 households from CGA were recruited Inclusion criteria intervention households: voluntary willingness to participate, stored water in the home, were using the filter, had a child under the age of 5 in the household, stored water in the home, and did not use bottled water as their main drinking water source Matched control households were recruited for intervention households based on similar socioeconomic status, located less than a km from intervention house, similar water source, child under age of 5 years old, voluntary willingness to participate, There were 4 households that did not complete the study because they dropped out or moved. *****417 individuals needed in each study arm for longitudinal study in order to yield a statistically significant detectable risk ratio of .75 between study groups at 75% power and alpha of .05. Need an average of 5 people (conservative estimate), requires minimum of 72 households. CONSERVATIVE SAMPLE SIZE BASED ON PREVIOUS WORK AND LITERATURE

Data Collection

• Cross-sectional - visit of 336 households who had a BSF between 0.5-8 years

• Longitudinal - monthly visits to over 200 households (Jan-May 2007) – 50 intervention households from each

organization (Hagar, CGA) and 100 matched control households

• Water quality - monthly sampling of raw, treated and stored water– Test for E. coli and turbidity reductions

Data Analysis• Cross-sectional survey

– Examined relationship between continued use and household water and sanitation practices

• Longitudinal prospective cohort– Examined water quality

improvements – Measured relationship

between filter use and reduced diarrhea cases across age cohorts via odds ratios (OR)

Cross-sectional Survey Results• 336 households enrolled in survey• 294 (87.5%) households reported still using the BSF• Average time in use 2.5 years; some in use for 8 years

05

1015

Per

cent

0 5 10 15time_use

Risk Factors for Sustained Use

• Factors associated with continued BSF use: OR (95% CI)– Receiving training: 2.04 (1.0-3.9)– Method of drawing water (using a dipper): 3.1

(1.6-6.1)– Deep well for water source: 2.6 (1.3-5.4)

• Factors associated with discontinued BSF use: – Boiling water 0.07 (0.02 - 0.3)

Longitudinal Study Results: Water quality

• Filters reduce E. coli concentrations in treated water by a mean of 95% (1.3 log10 reduction value)– Up to 4 log (99.99%) observed

• 55% of effluent water samples from filters were <10 E. coli/100ml (low risk)

• 82% reduction of turbidity from untreated to treated water

Presenter

Presentation Notes

For the longitudinal prospective cohort study of intervention and control households, the following results should be highlighted 75 households (36%) from Kandal, 26 households (13%) from Kompong Speu, 34 (16%) from Svay Rieng, 40 households (19%) in Kompong Thom and 32 (16%) from Kratie

Diarrhea disease reductions

0

0.05

0.1

0.15

0.2

0.25

0 1 2 3 4 5 6Household visit

Case

s/pe

rson

wee

k

BSF Households

Control

Presenter

Presentation Notes

This graph shows cases of diarrhea per person-week by visit The cases reported per person were always lower in BSF households throughout the study The general trend showed a decrease in diarrhea over the course of the study except for the second visit for BSF households. This could be because of seasonal change and water quality or over-reporting The control households showed a larger drop in cases per person-week in the second visit which may be due to seasonal change or under-reporting.

Longitudinal Study: Health

• Filters associated with a mean 44% reduction in diarrheal disease in users versus non users (OR=0.56, 95% CI 0.49-0.66)

• Group experiencing most protective effect, ages 2-4 (46% reduction for filter users)

• No significant protective effect for ages 0-2 (OR=0.89, 95% CI 0.6-1.2)– Southeast Asia children typically not weaned until

ages 2-3; so probably not/less exposed to filtered water

Conclusions• BSFs have sustained use in Cambodia• Filters improved water quality (1.3 log10 or

95% reduction of E. coli in raw water) and reduced diarrheal disease (44% compared to matched non-filter households)

• Diarrhea reductions comparable to other HWTS interventions

• Need to prevent recontamination through appropriately designed software (behaviors) and hardware (containers)

AcknowledgementsI would like to gratefully acknowledge the support and contribution of:

• Project staff: Proum Sorya, Van Sokheng, Oum Sopharo, Song Kimsrong, Uon Virak, Little Sokheng, Ken Sreymom, Monn Pong, Seiha, Um Saravuth

• Royal Government of Cambodia, Ministry of Rural Development – Dr.Mao Saray & Mr.Chea Samnang

• Hagar and CGA Program Managers, Mr.Yim Viriya & Mr.Me Kosal• WSP (World Bank) – Mr.Jan Willem Rosenboom, • Plan International - Mr.Peter Feldman• USAID – Dr.John Borrazzo• WHO SE Asia – Dr.Terrence Thompson • Samaritan’s Purse Canada (John Clayton, Andrew Buller, Marianne

Maertens)• Dr.Mickey Sampson - RDI-C, • Dr.Mark Sobsey, Douglas Wait, Dr.Joe Brown, Dr.Christine Stauber,

Dr.Kimberly Blauth, Mark Elliott and the Sobsey lab group

Questions?

kaida liang before i begin, i want to thank you for...

Documents