Monroe L. Weber-Shir k S chool of Civil and Environmental Engi neering Public Health Implications of Water Supply Improvements Did Environmental Engineers save the world?
Monroe L. Weber-Shirk
School of Civil and
Environmental Engineering
Public Health Implications of Water Supply ImprovementsPublic Health Implications of Water Supply Improvements
Did Environmental Engineers save the world?
Review: Public Health Implications of Water Supply Improvements
Review: Public Health Implications of Water Supply Improvements
The life expectancy transitionThe role of water supply, sanitation, and
hygieneIn the Global North a century agoIn the Global South
The U5MR connectionExposure Routes: breaking the cyclePathogens in the loopImplications for successful interventions
0
20
40
60
80
100
1650 1700 1750 1800 1850 1900 1950 2000 2050
Year
life
ex
pec
tan
cy (
yea
rs)
Pre-agrarian
Poor-agrarian Early C
ities
Modern Cities
The transition
0
5
10
15
20
25
30
35
1900 1910 1920 1930 1940 1950
year
deat
hs p
er 1
00,0
00
0
0.05
0.1
0.15
0.2
0.25
0.3
0 2000 4000 6000 8000 10000
GNP per person$1991, purchasing power parity
U5M
R
Human excreta
Animal excreta
Dry sanitation involving reuse
Waterborne sewage
Non recycling latrines
Soil
Surface water
Ground water
Food
Drinking water
Oral
Land application
Hands
Crops
Flies
Water
washing
Mean = life expectancy
0
5000
10000
15000
20000
25000
0 2 8 13 18 23 28 33 38 43 48 53 58 63 67 72 77 82 89
Mean age at death in interval (nearest year)
Num
ber
of d
eath
s / y
r (f
or 1
0000
0 bi
rths
/yr) Mean = life expectancyMean = life expectancy
0
5000
10000
15000
20000
25000
0 2 8 13 18 23 28 33 38 43 48 53 58 63 67 72 77 82 89
Mean age at death in interval (nearest year)
Num
ber
of d
eath
s / y
r (f
or 1
0000
0 bi
rths
/yr)
0
20
40
60
80
100
1650 1700 1750 1800 1850 1900 1950 2000 2050
Year
life
ex
pec
tan
cy (
yea
rs)
Life Expectancy Transition(Global North)
Life Expectancy Transition(Global North)
Only intended to indicate trends!
Pre-agrarian
Poor-agrarian
Ear
ly C
ities
Modern Cities
The transition
Who gets the credit?
Life expectancy in EnglandLife expectancy in England
From family reconstitution
(mostly rural)
From vital registration
males females
0
10
20
30
40
50
60
70
80
90
1600 1650 1700 1750 1800 1850 1900 1950 2000
Year
Lif
e ex
pec
tan
cy
Life Expectancy in SwedenLife Expectancy in Sweden
0
10
20
30
40
50
60
70
80
90
1750 1800 1850 1900 1950 2000
life
ex
pe
cta
nc
y a
t b
irth
males females
0
20
40
60
80
100
1650 1700 1750 1800 1850 1900 1950 2000 2050
Year
life
expe
ctan
cy (
year
s)Life Expectancy Transition
(Global South)Life Expectancy Transition
(Global South)
Based on no data! (just my overly generalized thoughts…) Increase in life expectancy is occurring later than in the
North Cities are generally benefiting sooner Huge variation between and within countries
Pre-agrarian Poor-agrarian
Wealthy
Poor
Distribution of deaths by age at death with mean = 75 years
Distribution of deaths by age at death with mean = 75 years
0
5000
10000
15000
20000
25000
30000
0 3 8 13 18 23 28 33 38 43 48 53 58 63 68 73 78 82 91
Mean age at death in interval (nearest year)
Nu
mbe
r of
dea
ths
/ yr
(for
100
000
bir
ths/
yr) Disease that takes a lifetime to kill (high
blood pressure, tobacco, cholesterol…)
Distribution of deaths by age at death with mean = 35 years
Distribution of deaths by age at death with mean = 35 years
Mean = life expectancy
0
5000
10000
15000
20000
25000
0 2 8 13 18 23 28 33 38 43 48 53 58 63 67 72 77 82 89
Mean age at death in interval (nearest year)
Nu
mbe
r of
dea
ths
/ yr
(for
100
000
bir
ths/
yr)
Why are these people dying
young?
Mortality due to leading factorsMortality due to leading factors
Water, Sanitation, Hygiene
Inadequate food
Air pollution
Burden of disease due to leading risk factors
Burden of disease due to leading risk factors
DALY:_______________________Disability-adjusted life year
Our focus in this course…
The role of Water Supply, Sanitation, and Hygiene
The role of Water Supply, Sanitation, and Hygiene
Contribute significantly to mortality and morbidity on the global level
Have an enormous influence on U5MR (under 5 mortality rate)
But why are these 3 items grouped together?What is the effect of safe drinking water?Let’s examine the role of safe drinking water in the life
expectancy transition
Mills-Reincke PhenomenonMills-Reincke Phenomenon
‘…. the purification of polluted public water-supplies reduces the general death-rate much more than it would be reduced by the saving of deaths from the commonly recognized water-borne disease, typhoid fever and Asiatic cholera alone.’
Sedgwick WT, MacNutt JS. On the Mills-Reincke phenomenon and Hazen's theorem concerning the decrease in mortality from diseases other than typhoid fever following the purification of public water-supplies. J.Infect.Dis. 1910; 7 : 489-564.
This is the “Environmental Engineers Saved the World” Hypothesis.
U.S. Typhoid Fever MortalityU.S. Typhoid Fever Mortality
0
5
10
15
20
25
30
35
1900 1910 1920 1930 1940 1950
year
deat
hs p
er 1
00,0
00
Chlorination was begun in Jersey City, N.J., in 1908. Adoption by other cities and towns across the US soon followed and resulted in the virtual elimination of waterborne diseases such as cholera, typhoid, dysentery and hepatitis A
Chlorination begins in Jersey City
Chlorine saved the day
Chlorine Cause and Effect:What else would you like to know…
Chlorine Cause and Effect:What else would you like to know…
What was the mortality rate before the introduction of chlorine?
When did other cities adopt chlorination?How did the mortality rate change for cities
when they began chlorinating?What other changes were occurring during
the 1900s that may have influenced mortality?
Typhoid Fever Mortality Baden, Germany 1855 to 1881
Typhoid Fever Mortality Baden, Germany 1855 to 1881
020406080
100120140160
1850 1860 1870 1880 1890
year
dea
thra
te p
er 1
00
,00
0
Typhoid decreased here before water supply improvements!
Typhoid fever death rate per 100,000 inhabitants per year in Albany, NY
Typhoid fever death rate per 100,000 inhabitants per year in Albany, NY
0
20
40
60
80
100
120
140
1890 1895 1900 1905 1910 1915 1920 1925
year
Dea
th ra
te p
er 1
00,0
00
Death rate per 100,000
Introduction of filtration
Introduction of disinfection
Flooding of the filtering unit
Increased chlorination
Typhoid decrease coincided with water filtration!
U.S. population supplied with filtered water
U.S. population supplied with filtered water
0%
10%
20%
30%
40%
50%
1880 1890 1900 1910 1920
year
perc
ent o
f urb
an p
opul
atio
n re
ceiv
ing
filte
red
wat
er slow
rapid
total
0
5
10
15
20
25
30
35
1900 1910 1920 1930 1940 1950
year
deat
hs p
er 1
00,0
00Reduction in typhoid might be correlated with installation of filters
Typhoid
Correlation between Water Supply Improvements and Public Health?Correlation between Water Supply Improvements and Public Health?
A causal link?FiltrationChlorination
Delayed response?No link?US 1900 – 1940
interpretationYour call (homework!)
Disease rates as measures of efficiency
Disease rates as measures of efficiency
“The final criterion of the efficiency of a purification plant is the absence or prevalence in the community of water-borne diseases. Typhoid fever being the most typical and widespread of such diseases, statistics of its prevalence are of much significance. Prior to the general introduction of purification works, the typhoid death rate was invariably high in many of our large cities drawing their suppy from polluted rivers and lakes. Most of these cities are now supplied with satisfactory water, and many records could be given showing the marked effect of water treatment on the typhoid rate. The following data for the cities of New Orleans, Pittsburgh and Cincinnati will suffice.”
Public Water-Supplies by Turneaure, Russell, Mead, Baker. John Wiley & Sons (1924) pages 430-431.
Evidence for a Causal Link:Pittsburgh, Philadelphia, Cincinnati
Evidence for a Causal Link:Pittsburgh, Philadelphia, Cincinnati
020406080
100120140160
1900 1910 1920 1930 1940
Year
Typ
hoid
mor
tali
ty r
ate
(per
100
,000
)
Typhoid
Filtration
Chlorination
01020304050607080
1900 1910 1920 1930 1940
Year
Typ
hoid
mor
tali
ty r
ate
(per
100
,000
)
Typhoid
Filtration
Chlorination
0
20
40
60
80
100
1900 1910 1920 1930 1940
Year
Typ
hoid
mor
tali
ty r
ate
(per
100
,000
)
Typhoid
Filtration
Chlorination
Pittsburgh, Cincinnati and New Orleans were used as evidence of the efficacy of filtrationPublic Water-Supplies by Turneaure, Russell, Mead, Baker. John Wiley & Sons (1924)
Delayed Response?Delayed Response?
0
10
20
30
40
50
1900 1910 1920 1930 1940
Year
Typ
hoid
mor
tali
ty r
ate
(per
100
,000
)
Typhoid
Filtration
Chlorination
0
5
10
15
20
25
30
35
1900 1910 1920 1930 1940
Year
Typ
hoid
mor
tali
ty r
ate
(per
100
,000
)
Typhoid
Filtration
Chlorination
0
5
10
15
20
25
1900 1910 1920 1930 1940
Year
Typ
hoid
mor
tali
ty r
ate
(per
100
,000
)
Typhoid
Filtration
Chlorination
“The steady reduction… is probably due in part to improved operation and in part to the gradual elimination of the disease from the community and so removing sources of contamination.”
Public Water-Supplies by Turneaure, Russell, Mead, Baker. John Wiley & Sons (1924)
Delayed Response?Delayed Response?
Gradual improvement in filtration plant operation
Gradual extension of water supply coverage
Gradual reduction in pathogen load in the population
01020304050607080
1900 1910 1920 1930 1940
Year
Typ
hoid
mor
tali
ty r
ate
(per
100
,000
)
Typhoid
Filtration
Chlorination
0
10
20
30
40
50
1900 1910 1920 1930 1940
Year
Typ
hoid
mor
tali
ty r
ate
(per
100
,000
)
Typhoid
Filtration
Chlorination
0
20
40
60
80
100
120
1900 1910 1920 1930 1940
Year
Typ
hoid
mor
tali
ty r
ate
(per
100
,000
)
Typhoid
Filtration
Chlorination
No Link?No Link?
New York
0
5
10
15
20
25
30
35
1880 1900 1920 1940year
Typ
hoid
mor
talit
y(p
er 1
00,0
00)
0
20MortalityNew sourceChlorinationFiltration
New York
Los Angeles
0
10
20
30
40
50
1880 1900 1920 1940year
Typ
hoid
mor
talit
y(p
er 1
00,0
00)
0
20MortalityNew sourceChlorinationFiltration
Los Angeles Minneapolis
0
20
40
60
80
1880 1900 1920 1940
year
Typ
hoid
mor
talit
y(p
er 1
00,0
00)
0
20MortalityNew sourceChlorinationFiltration
Minneapolis
Boston
0
20
40
60
80
1880 1900 1920 1940
year
Typ
hoid
mor
talit
y(p
er 1
00,0
00)
0
20MortalityNew sourceChlorinationFiltration
Boston
No Link?No Link?
San Francisco
0
20
40
60
80
1880 1900 1920 1940
year
Typ
hoid
mor
talit
y(p
er 1
00,0
00)
0
20MortalityNew sourceChlorinationFiltration
San Francisco
0
10
20
30
40
50
60
70
1900 1910 1920 1930 1940
Year
Typ
hoid
mor
tali
ty r
ate
(per
100
,000
)
Typhoid
Filtration
Chlorination
0
10
20
30
40
50
1900 1910 1920 1930 1940
Year
Typ
hoid
mor
tali
ty r
ate
(per
100
,000
)
Typhoid
Filtration
Chlorination
0
10
20
30
40
50
60
1900 1910 1920 1930 1940
Year
Typ
hoid
mor
tali
ty r
ate
(per
100
,000
)
Typhoid
Filtration
Chlorination
0
10
20
30
40
50
60
1900 1910 1920 1930 1940
Year
Typ
hoid
mor
tali
ty r
ate
(per
100
,000
)
Typhoid
Filtration
Chlorination
What else was happening?…education (one possibility)
What else was happening?…education (one possibility)
‘Infant care’ (US Children’s Bureau)12,000,000 copies
Baby care columns in leading newspapersCarried by nearly all newspapers by 1912
(though not a few years earlier)
‘Baby weeks’ By 1919: 17,000 local committees11,000,000 directly involved
Causes of diarrhoea according to ‘Diseases of children’
Causes of diarrhoea according to ‘Diseases of children’
1889 1899
Sour milk
Unripe fruit
Inhalation of sewer gas
Emanations from the soil
‘no doubt that the immediate cause is an infection of the alimentary canal, by …bacteria contained in milk or other forms of food’
EmpowermentPowerlessness!
Changes recommended: public health campaignChanges recommended: public health campaign
Breast feedBoil cow’s milk, sterilize bottlesProtect infants from persons known to be illControl fliesWash hands
You can improve your health!
Education of the PublicEducation of the Public
...the discovery of the possibilities of widespread social organization as a means of controlling disease was one which may almost be placed alongside the discovery of the germ theory of disease itself as a factor in the evolution of the modern public health campaign.
-Winslow (1929)
Confounding Factors:Order of InterventionsConfounding Factors:Order of Interventions
If the drinking water was contaminated with typhoid and you mounted an education campaign to encourage hand washing…You would conclude
If you installed a water treatment plant, but no one washed their hands…You would conclude
These interventions are necessary, but not sufficient because there are ________ disease transmission routes
No need to wash hands
No need for clean water
multiple
Typhoid in ReviewTyphoid in Review
Is it possible that education that led to improved hygiene was a significant source of the reduction in typhoid mortality?
This would suggest that water wasn’t the primary exposure route (unless individuals were taking steps to purify the water they drank)
We may never be able to untangle what happened with typhoid because multiple changes were occurring simultaneously
I’ll let you wrestle with who to give credit
Try again… Specific Disease Outbreaks (Attempt #2)
Try again… Specific Disease Outbreaks (Attempt #2)
Salmonella typhi was a bad eggInvestigate outbreaks and reported causes
TyphoidCholeraOther?
Check for evidence that it was waterborneCheck for evidence of protection by
filtration and/or chlorination
Cholera "Tramples the victors & the vanquished both."
Cholera "Tramples the victors & the vanquished both."
Seymour, Robert, 1798-1836. Artist.
John Snow: The great experimentJohn Snow: The great experiment
Snow's definitive work concerned the spread of cholera through water supplied by the Southwark Company and the Lambeth Company
Southwark obtained its water from the Thames at Batttersea, in the middle of London in an area almost certainly polluted with sewage
Lambeth Company obtained its water considerably upstream on the Thames, above the major sources of pollution
In an area containing about 300,000 residents the pipes of both companies were laid in the streets, and houses were connected to one or the other sources of supply.
Beautiful buildings, but the water…Beautiful buildings, but the water…
The view of three water companies by Hampton is southwest from the north side of the River Thames. The nearest building of the three companies is the Southwark and Vauxhall Water Company
Source: Anonymous. Illustrated London News, 1855. Graciously provided by Bryce Caller, January 10, 2001.
Southwark and Vauxhall Water Company
Southwark and Vauxhall Water Company
In 1850, the microbiologist Arthur Hassall wrote of the River Thames water they were using,"...a portion of the inhabitants of the metropolis are made to consume, in some form or another, a portion of their own excrement, and moreover, to pay for the privilege."
Next Cartoon presents John Edwards, owner of the Southwark Water Company, posing as Neptune ("Sovereign of the Scented Streams"). He is seen crowned with a chamber-pot, seated on a stool on top of a cesspool which doubles as the water-intake for the Southwark Water Company customers in south London.
Southwark and Vauxhall Water Company
Southwark and Vauxhall Water Company
Courtesy of the National Library of Medicine
The Grand Cholera ExperimentThe Grand Cholera Experiment
Those houses served by the Lambeth Company had a low incidence of cholera, lower than the average population of London as a whole
Those served by the Southwark Company had a very high incidence
The socioeconomic conditions, climate, soil, and all other factors were identical for the populations served by the two companies
Snow concluded that the water supply was transmitting the cholera agent
Snow's study is impressive since the germ theory of disease had not yet been established
Proof that cholera was waterborne
Drinking Water Treatment and Germ Theory
Drinking Water Treatment and Germ Theory
1829: First sand filter used to treat some of London's drinking water
1850: John Snow established the link between drinking water (from a contaminated well) and Cholera
1872: Poughkeepsie, NY installs first filter in US 1885: Sand filters are shown to remove bacteria 1892: Cholera outbreak in Hamburg, Germany
1892 Cholera outbreak in Hamburg Germany
1892 Cholera outbreak in Hamburg Germany
Large outbreak of Cholera in Hamburg 17,000 cases; 8,600 deaths Very few cases in neighborhoods served by Altona's
filtered water supply Hamburg's sewers were upstream from Altona's intake!
Altona's water intake and filter beds Hamburg's sewer outfalls
HamburgAltona
Elbe RiverHamburg's water intake
Altona vs. Hamburg: Cholera CasesAltona vs. Hamburg: Cholera Cases
Hamburg
Altona
Cases in Altona acquired in Hamburg
Cholera cases
Received water from Altona
Cholera was waterborne
Slow sand filtration may have protected Altona
Environmental Engineers are saving the world: Attempt #3
Environmental Engineers are saving the world: Attempt #3
So it isn’t clear whether or not environmental engineers saved us all from typhoid. (you will be the judge!)
We have some evidence that filtration and water source affect public health
Could we make a case for our relevance by comparing current populations?
Compare modern countries with low and high U5MR and see what is correlated with infant mortality
U5MR by National Income in the Early 1990s
U5MR by National Income in the Early 1990s
0
0.05
0.1
0.15
0.2
0.25
0.3
0 2000 4000 6000 8000 10000
GNP per person$1991, purchasing power parity
U5M
R
Low performers (l to r): Congo, Gabon, Botswana, Turkey, Brazil
High performers (l to r): Sri Lanka, China, Surinam, Jamaica, Costa Rica
Good and poor performersGood and poor performers
High Low
* as % of GNP
<5 mortality rate
GNP/person
%underweight (<5yrs)
% with safe water
immunization %
spend on health*
pop'n per doctor
soldiers per doctor
the
contrast
nutrition
public
health
political
support
High: Sri Lanka, China, Surinam, Jamaica, Costa Rica
Low : Congo, Gabon, Botswana, Turkey, Brazil
26104
34884214
191887658576
3.62.7
24403638
813
Good and poor performersGood and poor performers
total fertility rate
yrs school f's >25**
maternal mortality
radios per 100
newspapers per 100
status of
women
communications
2.74.6
52
116446
3418
63
** mean yrs of schooling for women over 25
High LowHigh: Sri Lanka, China, Surinam, Jamaica, Costa Rica
Low : Congo, Gabon, Botswana, Turkey, Brazil
<5 mortality rate
GNP/person
the
contrast
26104
34884214
Conclusions: Good and Poor PerformersConclusions: Good and Poor Performers
Safe water supply is correlated with decreasing U5MR
Lower fertility rate, higher female education, lower maternal mortality rate are all correlated with lower U5MR
Increased communication correlated with lower U5MR!
Can’t prove cause and effect using this type of study
How might education increase child survival?
How might education increase child survival?
The whole country runs better as the education level increasesEducation as an indicator of how well the country
responds to the needs of its citizensEducation helps the group
Individuals make changes in personal habits that improve their own health and the health of those they interact withEducation helps the individual
The whole country runs better as the education level increases
The whole country runs better as the education level increases
Increased knowledge and changed outlook
Increased effectsof professional ‘interventions’
Better health
Changed public under-standing & behaviour
Increased income and better nutrition
Better use of publicand private resources
Institutional modernizatio
n
Would a Cornell Education help?Would a Cornell Education help?
If you moved to a poor neighborhood in Tegucigalpa, Honduras and raised a family would your children have a lower risk of dying than your neighbors?
Is there anything that you might do that would increase the survival odds for your children?
Does education help the individual?
Role of Hygiene and EducationRole of Hygiene and Education
Research in developing countries has shown that improvements in hygiene and sanitation have an even greater impact upon water-related diseases than improvements in water quality
Improvements in sanitation and personal hygiene reduce fecal-oral transmission 3 ways Objects (especially household items and including hands) Water Food
Water QUANTITY may be more important than water quality
Remember the Millennium Development Goal?_________________________Improved, not necessarily safe!
Fecal-Oral PathwaysFecal-Oral Pathways
Human excreta
Animal excreta
Dry sanitation involving reuse
Waterborne sewage
Non recycling latrines
Soil
Surface water
Ground water
Food
Drinking water
Oral
Pathogen source
Sanitation method
Land application
Environment Transport
Hands
Crops
Flies
Water
HygieneWater treatmentSanitation
washing
Intervention - Waterborne Sewage replace Land Application
Intervention - Waterborne Sewage replace Land Application
Human excreta
Animal excreta
Dry sanitation involving reuse
Waterborne sewage
Non recycling latrines
Soil
Surface water
Ground water
Food
Drinking water
Oral
Pathogen source
Sanitation method
Land application
Environment Transport
Hands
Crops
Flies
Water
IncreaseNo ChangeDecreaseUnknown
washing
Intervention – Personal HygieneIntervention – Personal Hygiene
Human excreta
Animal excreta
Dry sanitation involving reuse
Waterborne sewage
Non recycling latrines
Soil
Surface water
Ground water
Food
Drinking water
Oral
Pathogen source
Sanitation method
Land application
Environment Transport
Hands
Crops
Flies
Water
washing
IncreaseNo ChangeDecreaseUnknown
Hypothetical InterventionHypothetical Intervention
What are the public health effects of providing pure drinking water in abundance to a community that practices land application of waste and poor personal hygiene?
Conclusions on Hygiene and Health and Water (1)
Conclusions on Hygiene and Health and Water (1)
In order to achieve the primary objective of improving the health status of the community there is a need to improve attitudes, both with respect to hygiene in home and general health education, and implement these in conjunction with community water supply and environmental sanitation programs.
Most waterborne diseases spread through exposure of food and drinking water to human feces.
Hence, the rate of infection may be reduced by improving practice for disposal of human waste, as well as improving hygiene in the home and water quality and food hygiene.
Home hygiene and environmental sanitation: a country situation analysis for IndiaK.J. NATH
Conclusions on Hygiene and Health and Water (2)
Conclusions on Hygiene and Health and Water (2)
A supply of safe water would be of little benefit if it became contaminated because of unhygienic practices in the home.
Correct storage and handling of food and drinking water should be an important component of any program for promoting domestic hygiene.
On the other hand, improvement in the hygiene behavior of a community cannot be sustained without a concurrent improvement in the quality of environmental sanitation and the supply of safe drinking water.
Home hygiene and environmental sanitation: a country situation analysis for IndiaK.J. NATH
What would it take to reduce Diarrhea (and U5MR)?
What would it take to reduce Diarrhea (and U5MR)?
88% of diarrhoeal disease is attributed to unsafe water supply, inadequate sanitation and hygiene.
Improved water supply reduces diarrhea morbidity by 21%.
Improved sanitation reduces diarrhea morbidity by 37.5%. The simple act of washing hands at critical times can
reduce the number of diarrhoeal cases by up to 35%. Additional improvement of drinking-water quality, such as
point of use disinfection, would lead to a reduction of diarrhea episodes of 45%.
1.8 million people die every year from diarrhoeal diseases (including cholera); 90% are children under 5, mostly in developing countries.
1.6 9/11 attacks per day…
In search of more evidenceIn search of more evidence
Challenge: Assemble additional evidence for (or against) the role of filtration and chlorination
Remember, our goal is to propose interventions that make a positive improvement in public health
One goal of this course is to assemble evidence for the basis of sound decisions
A 2nd goal is to provide a solid theoretical basis for the interventions
The case against looking for a Public Health Outcome
The case against looking for a Public Health Outcome
Epidemiological studies to measure a decrease in diarrhea in young children are Expensive Take a good deal of time Are not guaranteed to produce any meaningful results even from
the most successful program Diarrhea is caused by many different pathogens through
many different transmission routes Confounding factors Need to have an adequate control group Results have little diagnostic power
An Alternative to EpidemiologyAn Alternative to Epidemiology
WHO’s Minimum Evaluate Procedure
constructionfunctioning
O&Muse benefits
Review: Public Health Implications of Water Supply Improvements
Review: Public Health Implications of Water Supply Improvements
The life expectancy transition The role of water supply, sanitation, and hygiene
In the Global North a century ago In the Global South
The U5MR connection Exposure Routes: breaking the cycle Pathogens in the loop Implications for successful interventions
0
20
40
60
80
100
1650 1700 1750 1800 1850 1900 1950 2000 2050
Year
life
ex
pec
tan
cy (
yea
rs)
Pre-agrarian
Poor-agrarian Early C
ities
Modern Cities
The transition
0
5
10
15
20
25
30
35
1900 1910 1920 1930 1940 1950
year
deat
hs p
er 1
00,0
00
0
0.05
0.1
0.15
0.2
0.25
0.3
0 2000 4000 6000 8000 10000
GNP per person$1991, purchasing power parity
U5M
R
Human excreta
Animal excreta
Dry sanitation involving reuse
Waterborne sewage
Non recycling latrines
Soil
Surface water
Ground water
Food
Drinking water
Oral
Land application
Hands
Crops
Flies
Water
washing
Mean = life expectancy
0
5000
10000
15000
20000
25000
0 2 8 13 18 23 28 33 38 43 48 53 58 63 67 72 77 82 89
Mean age at death in interval (nearest year)
Num
ber
of d
eath
s / y
r (f
or 1
0000
0 bi
rths
/yr) Mean = life expectancyMean = life expectancy
0
5000
10000
15000
20000
25000
0 2 8 13 18 23 28 33 38 43 48 53 58 63 67 72 77 82 89
Mean age at death in interval (nearest year)
Num
ber
of d
eath
s / y
r (f
or 1
0000
0 bi
rths
/yr)
A sample of Waterborne Pathogens
Enteropathogenic Escherichia coli (EPEC) Vibrio cholerae - CholeraSalmonella typhi - Typhoid Cryptosporidium parvum Hepatitis A
Enteropathogenic Escherichia coli (EPEC)
Enteropathogenic Escherichia coli (EPEC)
Enteropathogenic Escherichia coli (EPEC) strains are one of several categories of pathogenic E. coli strains that cause diarrhea. EPEC infections are prevalent on six continents
In many parts of the world, EPEC strains are the most common bacterial cause of diarrhea in infants
Disease due to EPEC can be severe, refractory to oral rehydration, protracted, and lethal
Cryptosporidium parvumCryptosporidium parvum
Cryptosporidium parvum, a single-celled animal, i.e., a protozoa, is an obligate intracellular parasite.
Cryptosporidium sp. infects many herd animals (cows, goats, sheep among domesticated animals, and deer and elk among wild animals). It is currently thought that the form infecting humans is the same species that causes disease in young calves.
The infective stage of the organism, the oocyst is 3 mm in diameter.
The sporocysts are resistant to most chemical disinfectants, but are susceptible to drying and the ultraviolet portion of sunlight.
How widespread is Cryptosporidium?This might affect our interventions.
Hepatitis A VirusHepatitis A Virus
Hepatitis A is usually a mild illness characterized by sudden onset of fever, malaise, nausea, anorexia, and abdominal discomfort, followed in several days by jaundice. The infectious dose is unknown but presumably is 10-100 virus particles.
HAV is excreted in feces of infected people and can produce clinical disease when susceptible individuals consume contaminated water or foods.
In developing countries, the incidence of disease in adults is relatively low because of exposure to the virus in childhood. (Immunity!)
In the U.S., the percentage of adults with immunity increases with age (10% for those 18-19 years of age to 65% for those over 50).
Implications for Successful Interventions
Implications for Successful Interventions
Break the major pathogen loops……for the major pathogensHygiene is importantSanitation (waste disposal) is importantWe need more information on the efficacy
of the various water purification technologies so we can break the waterborne route