Transcript Water, sanitation, hygiene & environmental health

Water, sanitation, hygiene &
environmental health
Pete Kolsky
Energy and Water Department
Outline
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Some facts about water, san and
health
Historical evolution
Classification by transmission
The Literature of impact studies
The nature of the problem
Conclusions for practitioners
Some water, sanitation and
health numbers
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Faecal-oral (focus of this presentation)
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Diarrhoeal disease
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2 million deaths/year from diarrhoea, mostly under 5
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Jumbo jet crash every hour and a half…
One billion cases/year
4.3% of Burden of Disease DALYs
88% (?) attributable to inadequate WSH
1/3 of developing world pop’n carry intestinal worms
200 million infected by schistosomiasis (bilharzia)
6-9 million blind from trachoma (1/4 reduced by
adequate water supply)
Natural chemical hazards
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Arsenic
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Skin lesions, various cancers
“20 to 60” million exposed in Bangladesh
Major problem other parts of S. Asia, also
Argentina, Chile, China, Hungary, Mexico, Peru
Fluorosis
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Dental damage, crippling bone damage
“affects millions” (WHO) but often of mild form
Historical evolution: water
quality and health
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John Snow
Cholera
Broad Street Pump 1854
Water Companies' Studies
William Budd Typhoid in 1850's-60's
Koch
Cholera
vs. Pettenkoffer
Hamburg/Altona 1892
1937 Croydon Typhoid
And many more…
Characteristics of these (and
other) waterborne outbreaks
1. True outbreaks…sudden spikes
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Very visible and dramatic!!
Politically hot!
2. Common source…the water supply
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If you’re a water engineer…you don’t want one on
your watch!
Cholera is the water engineer’s best friend…Money
for chlorine suddenly becomes available…
3. Until 1970s, water quality dominated
environmental health perception of diarrhoea
Classifications of disease
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Classification usually by organism (viral,
bacterial, etc) or organ (diseases of
head, heart, liver etc.)
Classification by transmission route
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Bradley’s great innovation in 1970s
If you know how it’s spread, you know
how to stop it…
…so engineers loved it!
The F-Diagramme
Water supply
Sanitation
Fluids
Hygiene
Fingers
Faeces
Food
Flies
Fields/
Floors
Future
Victim
The great debates of the 80s
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Water-borne or water-washed?
 Is water quality or water quantity more important?
Review of epi in ‘83 revealed fundamental challenges
Blum, D. and R. Feachem, Int J Epidemiol 1983, 12, pp. 357-365
Lack of control
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One-to-one (clustreing)
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Confounding variables (inc. age)
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Recall
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Diarrhoeal definition
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Usage
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Seasonality
These issues are real, and are still grave threats to ‘quick and dirty’
project level impact assessments!!
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Results from Esrey, 1985
Type of
Intervention
All interventions
No of
Results
53
Median
Reduction
22
Range
Water quality
9
16
0-90
Water availability
17
25
0-100
Water quality
and availability
Excreta disposal
8
37
0-82
10
22
0-48
(Esrey, S.A. et al., WHO Bull, 63(4): 757-772, 1985)
0-100
Esrey (1985) by disease
Disease or
infection
Cholera
Range
No of
results
11
Median
reduction
41
Shigella
27
48
0-81
Entamoeba
histolytica
Giardia
lamblia
17
2
0-80
10
0
0-20
0-91
Esrey’s update in 1991
Intervention
Water & San
Rigorous
All Studies
Studies
No Med % No Med %
reduct
reduct
7
20
2
30
Sanitation
Water Quality and Quantity
11
22
22
16
5
2
36
17
Water Quality
7
17
4
15
Water Quantity
7
27
5
20
Hygiene
6
33
6
33
Esrey et al., WHO Bull, 69(5): 609-621 (1991)
2004 Fewtrell, Colford update
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Why do more?
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More studies
Statistically rigorous meta-analysis
HH water treatment new player
“Water, sanitation and Hygiene: Interventions and diarrhoea
A systematic review and meta-analysis”, Lorna Fewtrell and
John M. Colford, Jr. HNP Discussion Paper, World Bank 2004.
Water, sanitation, and hygiene interventions to reduce
diarrhoea in less developed countries: a systematic review
and meta-analysis, L. Fewtrell, R. Kaufmann, et al. Lancet
Infectious Diseases, Vol 5, pp 42-52. Jan 2005.
Some of the main results
Multiple interventions
Hygiene (good studies)
Sanitation
Water House Conn (good studies)
HH treatment (good studies)
No
studies
5
8
2
1
8
%
reduction
33
45
32
38
39
lower
24
25
13
35
19
•Above are highlights…
• Strong, detailed report and bibliography, and
documentation of approach
upper
41
60
47
41
54
Reduction in diarrhea morbidity (%)
70
Previous reviews
Fewtrell et al. (2004)
60
50
40
30
20
10
0
(a) Sanitation
(b) Water
availability
(c) Water
quality
(d) Hygiene
promotion
(e) Hand
washing
Previous reviews:
a–d
Esrey SA et al. (1991) Bull WHO 69 (5): 609-621
e
Curtis V, Cairncross S (2003) Lancet Inf Dis 3: 275-281.
Taken from S. Cairncross RWSSTG BBL “ The Health Impact of
Sanitation”, Aug 2004.
Major new conclusions from
Fewtrell, Colford, Kaufmann
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Water quality at HH is shown as significant…
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further reviews forthcoming…some skeptics
remain
Hygiene is reconfirmed as an effective
intervention
Combining interventions does not appear to
have synergistic effect, contrary to popular
public health belief
A step back from all of this…
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We don’t live in an “average” world…
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Mountains of Peru are different from slums of
South Asia
e.g. soil and food contamination risks higher in
China, Vietnam than in Africa…
Briscoe (Briscoe, J., Am J Epidemiol
1984;120:449-55) sheds even more light in a
non-linear world…
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If disease incidence not linearly proportional to
transmission, then “impact” attribution easily
skewed
The F-diagramme revisited
Water supply
Sanitation
Fluids
Hygiene
Fingers
Faeces
Food
Flies
Fields/
Floors
Future
Victim
How people see their city
River &
Environs
City
Peri- Ward
domestic
Home
(street,
school,
workplace)
An environmental view
Home
Peridomestic
Ward
(street,school,
workplace)
City
Central Treatment
Works
Collectors
Street
Sewers
House
Connections
A public health view
Sewer Mains
River &
Environs
Street Sewer
City
Interceptor/
Collector
Treatment
Plant/Outfall
Peri- Ward
domestic
Home
House
Connection
Take home messages…
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Diarrhoea is a huge problem in child health
Water, sanitation and hygiene can reduce diarrhoea
between 25-50%…
Very broad consensus that:
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Focus on the household…
Hygiene matters!
Water quality matters, but it’s not “just” water
quality…faecal contamination gets around many ways
Sanitation, WS infrastructure can make hygiene possible!
Health studies are tough…live with indicators rather than
“health outcome”
HH water treatment continues to be a growing focus of
attention…perhaps even more relevant for chem. contam.
Thank you for your attention!