Transcript Pathogens - Cornell University

Public Health Implications of
Water Supply Improvements
Did Environmental Engineers save
the world?
Monroe L. Weber-Shirk
School of Civil and
Environmental Engineering
AguaClara needs a few bright
(i.e. Cornell) students
 To create improved and more detailed design
algorithms to facilitate the global spread of the
AguaClara technologies
 To identify and trap for design tool failures
 To craft clear customized-automated documentation
of the designs in both English and Spanish
 To research methods to improve performance and
reduce costs
 To tell the AguaClara story and raise financial
support
100
80
Modern
tie
The transition
Pre-agrarian
Poor-
ly
Ci
20
rian
agra
Ea
r
40
Cities
s
60
0
1650 1700 1750 1800 1850 1900 1950 2000 2050
The life expectancy transition
deaths per 100,000
Year
The role of water supply, sanitation, and
hygiene
35
30
25
20
15
10
5
0
1900
1910
1920
1930
1940
1950
year
0.3
U5MR
0.25
0.2
0.15
0.1
0.05
0
0
25000
Number of deaths / yr
(for 100000 births/yr)
life expectancy (years)
Review: Public Health Implications
of Water Supply Improvements
20000
Mean = life expectancy
15000
10000
5000
0
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)
2000
4000
6000
8000
10000
In the Global North a century ago
In the Global South
GNP per person
$1991, purchasing power parity
The U5MR connection
washing
Human
excreta
Dry sanitation
involving reuse
Waterborne
sewage
Non recycling
latrines
Animal
excreta
Land
application
Hands
Drinking
water
Surface
water
Water
Ground
water
Oral
Crops
Food
Soil
Flies
Exposure Routes: breaking the cycle
Pathogens in the loop
Implications for successful interventions
life expectancy (years)
Life Expectancy Transition
(Global North)
100
Only intended to indicate trends!
80
60
The transition
40
Pre-agrarian
20
0
1650 1700 1750 1800 1850 1900 1950 2000 2050
Year
Who gets the credit?
Life expectancy in England
90
males
females
80
Life expectancy
70
60
50
40
30
20
10
From family reconstitution
From vital registration
(mostly rural)
0
1600
1650
1700
1750
1800
Year
1850
1900
1950
2000
Life Expectancy in Sweden
90
life expectancy at birth
80
70
60
50
40
30
20
10
0
1750
1800
1850
males
1900
females
1950
2000
life expectancy (years)
Life Expectancy Transition
(Global South)
100
80
60
40
 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
20
0
1650 1700 1750 1800 1850 1900 1950 2000 2050
Year
Distribution of deaths by age at
death with mean = 75 years
(for 100000 births/yr)
Number of deaths / yr
30000
Disease that takes a lifetime to kill (high
blood pressure, tobacco, cholesterol…)
25000
20000
15000
10000
5000
0
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)
Distribution of deaths by age at
death with mean = 35 years
Number of deaths / yr
(for 100000 births/yr)
25000
Mean = life expectancy
20000
Why are these
people dying
young?
15000
10000
5000
0
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)
Mortality due to leading factors
Inadequate food
Water, Sanitation, Hygiene
Air pollution
Burden of disease due to leading
risk factors
Disability-adjusted life year
DALY:_______________________
Our focus in this course…
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 Phenomenon
‘…. the purification of polluted public watersupplies 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.
deaths per 100,000
U.S. Typhoid Fever Mortality
35
30
25
20
15
10
5
0
1900
Chlorination begins
in Jersey City
1910
1920
1930
1940
year
Chlorine saved the day
1950
 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
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?
deathrate per 100,000
Typhoid Fever Mortality
Baden, Germany 1855 to 1881
160
140
120
100
80
60
40
20
0
1850
1860
1870
1880
1890
year
Typhoid decreased here before water supply improvements!
Typhoid fever death rate per 100,000
inhabitants per year in Albany, NY
Death rate per 100,000
140
Death rate per 100,000
120
Introduction of filtration
100
Introduction of disinfection
80
Flooding of the filtering unit
60
Increased chlorination
40
20
0
1890
1895
1900
1905
1910
year
1915
1920
Typhoid decrease coincided with water filtration!
1925
deaths per 100,000
U.S. population supplied
with filtered water
35
30
25
20
15
10
5
0
percent of urban population
receiving filtered water
1900
Typhoid
1910
1920
1930
year
50%
slow
rapid
total
40%
30%
20%
10%
0%
1880
1890
1900
1910
1920
year
Reduction in typhoid might be correlated with
installation of filters
1940
1950
Correlation between Water Supply
Improvements and Public Health?
A causal link?
Filtration
Chlorination
Delayed response?
No link?
US 1900 – 1940
interpretation?
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 waterborne 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 supply 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:
New Orleans, Pittsburgh, Cincinnati
New Orleans, LA
Pittsburg, PA
Typhoid
Filtration
Chlorination
50
40
30
20
10
0
1900
1910
1920
1930
1940
Typhoid mortality rate
(per 100,000)
Typhoid mortality rate
(per 100,000)
60
160
140
120
100
80
60
40
20
0
1900
Year
Typhoid
Filtration
Chlorination
1910
1920
1930
1940
Year
Typhoid mortality rate
(per 100,000)
Cincinatti, OH
90
80
70
60
50
40
30
20
10
0
1900
Typhoid
Filtration
Chlorination
1910
1920
Year
1930
Pittsburgh, Cincinnati and
New Orleans were used as
evidence of the efficacy of
filtration
1940
Public Water-Supplies by Turneaure, Russell,
Mead, Baker. John Wiley & Sons (1924)
Let’s look at all the data using log
scale (showing improvement ratio)
New
Philadelphia,
Milwaukee,
Baltimore,
Cleveland,
Jersey
Louisville,
Cincinatti,
St.
Memphis,
Pittsburg,
Chicago,
Detroit,
Louis,
Orleans,
City,
MI
MO
PA
MD
IL
TN
OH
KY
WI
NJ
PA
LA
Typhoid mortality rate
(per 100,000)
100
Typhoid
Filtration
Chlorination
10
1
0.1
1900
1910
1920
Year
1930
1940
Trying to Understand the Data
“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
Public Water-Supplies by Turneaure, Russell,
contamination.”
Mead, Baker. John Wiley & Sons (1924)
What do you think?
What else was happening?
…education (one possibility)
‘Infant care’ (US Children’s Bureau)
12,000,000 copies
Baby care columns in leading newspapers
Carried by nearly all newspapers by 1912
(though not a few years earlier)
‘Baby weeks’
By 1919: 17,000 local committees
11,000,000 directly involved
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’
Powerlessness!
Empowerment
Changes recommended:
public health campaign
Breast feed
Boil cow’s milk, sterilize bottles
Protect infants from persons known to be ill
Control flies
Wash hands
You can improve your health!
Education 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 Interventions
 If the drinking water was contaminated with
typhoid and you mounted an education campaign
to encourage hand washing…
 You would conclude
No need to wash hands
 If you installed a water treatment plant, but no one
washed their hands…
 You would conclude No need for clean water
 These interventions are necessary, but not
sufficient because there are ________
multiple disease
transmission routes
Reading the Typhoid Data
How long did it take for typhoid incidence
30 to 40 years
to decrease? _____________
If typhoid was waterborne how long should
it have taken for filtration and chlorination
A few weeks
to eliminate typhoid? _____________
How does milk get typhoid?
Human excrement (milker’s hands?)
or bovine excrement
My Typhoid Conclusions
 The reduction was not due to a one time
centralized change
 Not due to filtration
 Not due to chlorination
 Was due to changes that occurred at different
times throughout the population
 Improved hygiene
 Installation of toilets in bathrooms with sinks to wash hands
 Education encouraging hand washing
 Better food handling practices
 Milk pasteurization
 Refrigeration
 Public Health Education
Maybe Env. Eng. saved the world
from Cholera
Check for evidence that it was waterborne
Check for evidence of protection by
filtration and/or chlorination
Sniffing out Cholera
Courtesy of the National Library of Medicine
Cholera "Tramples the victors & the
vanquished both."
Seymour, Robert, 1798-1836. Artist.
John 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…
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
 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
Courtesy of the National
Library of Medicine
The 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
 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
Altona's water
intake and
filter beds
Altona
Hamburg
Hamburg's sewer outfalls
Hamburg's water intake
Elbe River
 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 vs. Hamburg: Cholera Cases
Cholera cases
Cases in Altona acquired in Hamburg
Received water from Altona
Altona
Cholera was waterborne
Slow sand filtration
may have protected
Altona
Hamburg
Environmental Engineers are saving
the world: Attempt #3
 Environmental engineers probably didn’t save us
all from typhoid.
 We have some evidence that filtration and water
source affect public health from cholera
 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
Low performers (l to r):
Congo, Gabon, Botswana,
Turkey, Brazil
0.3
U5MR
0.25
0.2
0.15
High performers (l to r):
Sri Lanka, China, Surinam,
Jamaica, Costa Rica
0.1
0.05
0
0
2000
4000
6000
8000
GNP per person
$1991, purchasing power parity
10000
Good and poor performers
High: Sri Lanka, China, Surinam, Jamaica, Costa Rica
Good Poor
Low : Congo, Gabon, Botswana, Turkey, Brazil
<5 mortality rate
GNP/person
%underweight (<5yrs)
% with safe water
immunization %
spend on health*
pop'n per doctor
soldiers per doctor
26
104
3488
4214
19
18
87
65
85
76
3.6
2.7
2440
3638
8
13
the
contrast
nutrition
public
health
* as % of GNP
political
support
Good and poor performers
High: Sri Lanka, China, Surinam, Jamaica, Costa Rica
Good Poor
Low : Congo, Gabon, Botswana, Turkey, Brazil
<5 mortality rate
GNP/person
total fertility rate
yrs school f's >25**
maternal mortality
radios per 100
newspapers per 100
** mean yrs of schooling for women over 25
26
104
3488
4214
2.7
4.6
5
2
116
446
34
18
6
3
the
contrast
status of
women
communications
Income disparity?
Conclusions: 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
Fecal-Oral Pathways
Pathogen
source
Sanitation
method
Hygiene
Water treatment
Sanitation
Environment Transport
washing
Human
excreta
Dry sanitation
involving reuse
Waterborne
sewage
Non recycling
latrines
Animal
excreta
Land
application
Hands
Drinking
water
Surface
water
Water
Ground
water
Oral
Crops
Food
Soil
Flies
Water Storage and Hygiene
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…
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 Epidemiology
WHO’s Minimum Evaluate Procedure
construction
functioning
O&M
use
benefits
Assumption that by implementing good practices that
health will follow
We need to identify the crucial good hygiene practices
Develop infrastructure that reliably delivers safe water
and that minimizes contact with human waste
A few good practices
?
1 Convenient water source to facilitate washing
2 Education about the disease pathways and good
hygiene practices
3 Safe waste handling to reduce contamination in
the home and to others in the local community
4 Safe storage of water (or continuous supply) to
prevent contamination in the home
5 Safe water at the tap to eliminate pathogens
from the water source
100
80
Modern
Cities
tie
s
60
The transition
Ci
Pre-agrarian
Poor-
20
rian
agra
ly
40
Ea
r
life expectancy (years)
Review: Public Health Implications
of Water Supply Improvements
0
1650 1700 1750 1800 1850 1900 1950 2000 2050
deaths per 100,000
Year
35
30
25
20
15
10
5
0
1900
1910
1920
1930
1940
1950
year
0.3
U5MR
0.25
0.2
0.15
0.1
0.05
0
0
2000
4000
 The life expectancy transition
 The role of water supply, sanitation, and hygiene
Cornell Engineering Alumni
 In the Global North a century ago
Association
 In the Global South
<[email protected]>
 The U5MR connection
 Exposure Routes: breaking the cycle
 Contaminants
 Implications for successful interventions
6000
8000
GNP per person
$1991, purchasing power parity
Number of deaths / yr
(for 100000 births/yr)
25000
20000
Mean = life expectancy
15000
10000
5000
0
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)
washing
Human
excreta
Dry sanitation
involving reuse
Waterborne
sewage
Non recycling
latrines
Animal
excreta
Land
application
Hands
Drinking
water
Surface
water
Water
Ground
water
Oral
Crops
Food
Soil
Flies
10000
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?
Is there specific knowledge that makes a
difference?
Role 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
Consistent with my Typhoid hypothesis (indoor toilets with sinks)
 Improvements in sanitation and personal hygiene reduce fecaloral 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 is a good first step!
The whole country runs better as the
education level increases
Increased knowledge and
changed outlook
Institutional
modernization
Changed public understanding & behaviour
Increased effects
of professional
‘interventions’
Better use of public
and private resources
Better health
Increased income
and better nutrition
How might education increase child
survival?
 The whole country runs better as the education
level increases
 Education as an indicator of how well the country
responds to the needs of its citizens
 Education helps the group
 Individuals make changes in personal habits that
 improve their own health
 and the health of those they interact with
 Education helps the individual
Intervention - Waterborne
Sewage replace Land Application
Pathogen
source
Sanitation
method
Increase
No Change
Decrease
Unknown
Environment Transport
washing
Human
excreta
Dry sanitation
involving reuse
Waterborne
sewage
Non recycling
latrines
Animal
excreta
Land
application
Hands
Drinkin
g water
Surface
water
Water
Ground
water
Oral
Crops
Food
Soil
Flies
Intervention – Personal Hygiene
Pathogen
source
Sanitation
method
Increase
No Change
Decrease
Unknown
Environment Transport
washing
Human
excreta
Dry sanitation
involving reuse
Waterborne
sewage
Non recycling
latrines
Animal
excreta
Land
application
Hands
Drinkin
g water
Surface
water
Water
Ground
water
Oral
Crops
Food
Soil
Flies
Hypothetical 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?
Continued transmission of pathogens on solid
objects (hands, food, dishes)
Hygiene education and empowerment could
improve health substantially especially given the
abundance of water
Brainstorm
 What are the public health issues of
the way water is handled?
 You are about to eat lunch in this
home. What are the risks?
 Water is carried from a
spring that is 0.5 km away
 Water from a mountain
stream is piped to the
house (every 3rd day)
Contaminants
 Pathogens
 Sediment
 Turbidity (light scatter)
 Inorganic or organic particles
 Inhibits disinfection
 pathogens “hide”
 Chlorine demand
 Dissolved Natural organic matter
 Color (absorb light)
 Chlorine demand
 Combine with chlorine to produce Disinfection By Products
 Arsenic
 Nitrate
 Synthetic organic compounds
A sample of Waterborne Pathogens
Enteropathogenic Escherichia coli (EPEC)
Vibrio cholerae - Cholera
Salmonella typhi - Typhoid
Cryptosporidium parvum
Hepatitis A
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 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 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).
What works to improve health?
 Residual protection is necessary*
 Chlorine
 Locked down POU treatment systems (with faucet)
 User can’t get their hands into the system
 But they could still put the water into a cup that isn’t clean
 SODIS (because you drink out of the container)
 Product is key for chlorine (technology matters!)
 Quality assured
 Technically correct
 Implementable
CDC safe water program results
*Is it the chlorine residual or is it that to get a
chlorine residual the water has to be clear?
Implications for Successful
Interventions
 Break the major pathogen loops…
 …for the major pathogens
 Remove sediment and color for effective
disinfection
 Household Hygiene is important
 Sanitation (waste disposal) is important
 We need more information on the efficacy of the
various water purification technologies so we can
break the waterborne route
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 India
K.J. NATH
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 India
K.J. NATH
Conclusions on Hygiene and Health
and Water (3)
 Consistent supply of clean water is important
 Hand washing
 Household hygiene (food, dishes, work surfaces)
 Clean water must be protected from contamination
in the home
 Pilas used for water storage in Central America provide
a direct path for contamination within a household
 Elevated enclosed tanks would be a much better
solution (see Mexico!)
What did we forget?
 What do people want?
 Easy access to plenty of safe, aesthetically pleasing
water
looks and taste/smell
 Judge based on __________________________
 Will they be willing to pay for and maintain more
expensive infrastructure to have aesthetically
pleasing water?
 We are competing with bottled water
 Can we make tap water as reliable as bottled water?