Water, sanitation, hygiene & environmental health

Pete KolskyEnergy and Water Department

Outline 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

Faecal-oral (focus of this presentation) Diarrhoeal disease

2 million deaths/year from diarrhoea, mostly under 5 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 Arsenic

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

Dental damage, crippling bone damage “affects millions” (WHO) but often of mild form

Historical evolution: water quality and health

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

outbreaks1. True outbreaks…sudden spikes

Very visible and dramatic!! Politically hot!

2. Common source…the water supply 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 Classification usually by organism

(viral, bacterial, etc) or organ (diseases of head, heart, liver etc.)

Classification by transmission route 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

Faeces

Future Victim

Fluids

Fingers

Flies

Fields/Floors

Sanitation

Food

Hygiene

Water supply

The great debates of the 80s 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 One-to-one (clustreing) Confounding variables (inc. age) Recall Diarrhoeal definition Usage Seasonality

These issues are real, and are still grave threats to ‘quick and dirty’ project level impact assessments!!

Results from Esrey, 1985Type of

InterventionNo of

ResultsMedian

ReductionAll interventions 53 22

Water quality 9 16

Water availability 17 25

Water qualityand availability

8 37

Excreta disposal 10 22

(Esrey, S.A. et al., WHO Bull, 63(4): 757-772, 1985)

Range

0-1000-90

0-100

0-82

0-48

Esrey (1985) by diseaseDisease or infection

No of results

Median reduction

Cholera 11 41

Shigella 27 48

Entamoeba histolytica

17 2

Giardia lamblia

10 0

Range0-910-810-800-20

Esrey’s update in 1991

Esrey et al., WHO Bull, 69(5): 609-621 (1991)InterventionNo Med

%reduct

No Med % reduct

Water & San 7 20 2 30Sanitation 11 22 5 36Water Quality and Quantity 22 16 2 17Water Quality 7 17 4 15Water Quantity 7 27 5 20Hygiene 6 33 6 33

All StudiesRigorous Studies

2004 Fewtrell, Colford update

Why do more? 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 reducediarrhoea in less developed countries: a systematic reviewand meta-analysis, L. Fewtrell, R. Kaufmann, et al. Lancet Infectious

Diseases, Vol 5, pp 42-52. Jan 2005.

Some of the main results

•Above are highlights…• Strong, detailed report and bibliography, and documentation of approach

No studies

% reduction lower upper

Multiple interventions 5 33 24 41Hygiene (good studies) 8 45 25 60Sanitation 2 32 13 47Water House Conn (good studies) 1 38 35 41HH treatment (good studies) 8 39 19 54

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.

0

10

20

30

40

50

60

70

(a) Sanitation (b) Wateravailability

(c) Waterquality

(d) Hygienepromotion

(e) Handwashing

Redu

ctio

n in

dia

rrhe

a m

orbi

dity

(%) Previous reviews Fewtrell et al. (2004)

Taken from S. Cairncross RWSSTG BBL “ The Health Impact of Sanitation”, Aug 2004.

Major new conclusions from Fewtrell, Colford, Kaufmann

Water quality at HH is shown as significant… 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…

We don’t live in an “average” world… 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… If disease incidence not linearly proportional to

transmission, then “impact” attribution easily skewed

The F-diagramme revisited

Faeces

Future Victim

Fluids

Fingers

Flies

Fields/Floors

Sanitation

Food

Hygiene

Water supply

WardCity

River & Environs

Peri-domestic

(street, school, work-place)

Home

How people see their city

(street,school, workplace)

Peri-domestic

Street Sewers

Home

House Connections

An environmental view

Central Treatment Works

City

Collectors

Ward

Ward

Sewer Mains

House Connection

Home

Peri-domestic

Street Sewer

City

Interceptor/ Collector

River & Environs

Treatment Plant/Outfall

A public health view

Take home messages… Diarrhoea is a huge problem in child health Water, sanitation and hygiene can reduce diarrhoea

between 25-50%… Very broad consensus that:

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!