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Burden of disease of water borne diseases Water and sanitation projects
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Global Burden of Disease
Introduction to Household Water Treatment and Safe Storage, Module 1.2
Dr. Richard Johnston
WHO Collaborating Centre
for Sanitation and Water
in Developing Countries
Introduction to HWTS | 2
● Diseases caused by unsafe water
and sanitation ● Water-borne
● Water-washed
● Water-based
● Water-related
● Global burden of disease ● Mortality
● Morbidity
Introduction
Introduction to HWTS | 3
● 8.4 deaths/1,000 ● 55 million people per year
● 19.9 births/1,000 ● 135 million people per year
● About 1.1% increase per year ● Doubling every 60 years
Birth, taxes, and death
Introduction to HWTS | 4
“Bradley Classification”
●Water-borne
●Water-washed
●Water-based
●Water-related
Disease Classification System
Introduction to HWTS | 5
Water-borne diseases
Caused by ingestion of water
●Diarrheal diseases ● Rotavirus
● Cholera, Shigella
● Cryptosporidiosis
●Hepatitis A and E
●Polio
Improve water quality
Introduction to HWTS | 6
Water-washed diseases
Caused by poor hygiene due to
lack of water
●Most water-borne diseases
●Trachoma
●Acute respiratory infections
Increase water quantity
Introduction to HWTS | 7
Water-based diseases
Caused by parasites which live
part of their life cycle in water
●Schistosomiasis (bilharzia)
●Dracunculiasis (Guinea worm)
Target aquatic organism host
Protect surface water bodies
Introduction to HWTS | 8
Water-related diseases
Caused by insects which breed
in water
●Malaria
●Dengue fever
Remove habitat
Introduction to HWTS | 9
● Many diseases are related to poor
water, sanitation, and hygiene
● Water-borne diseases are caused
by ingestion of contaminated
drinking-water
● HWTS can reduce burden of water-
borne diseases ● Not water-washed, water-based, or water-
related diseases
Summary
Introduction to HWTS | 10
Mini-Quiz
● Arrange the following five diseases in order of the number of deaths per year
Tuberculosis
Diarrheal disease
Lower respiratory
infections
(e.g. pneumonia)
Malaria
Measles
Introduction to HWTS | 11
Mini-Quiz
● Source: WHO in 2014 published figures for 2012.
Tuberculosis
Diarrheal disease
Lower respiratory
infections
Malaria
Measles
935,000
1,498,000
3,051,000
618,000
130,000
Introduction to HWTS | 12
● Causes 1.5 million deaths per year
● 1 in 10 deaths for children < 5 years ● 1,000 child deaths per day
● Second only to respiratory infection
among infectious diseases
● 56% of diarrheal deaths attributed to
inadequate water, sanitation and
hygiene
Diarrheal disease
Introduction to HWTS | 13
Disability Adjusted
Life Years (DALYs)
● DALY = YLL + YLD
● YLL = Years of Life Lost
Number of deaths × Standard
life expectancy at age of death in
years
● YLD = Years Lived with Disability
Number of incident cases ×
Disability weight × Average
duration of the case (years)
Introduction to HWTS | 14
● Diarrhea causes 52.5 M DALYs/year ● 3.1% of global total
● 9% of child disease burden
● India 13.6 M
● China 3.9 M
● Nigeria 3.9 M
● Pakistan 3.3 M
● DRC 3.3 M ● 10% of all DALYs
Diarrheal morbidity
Source: WHO, 2008
Introduction to HWTS | 15
Global Burden of Disease 2010 Study (IHME)
Introduction to HWTS | 16
● Similar approach to WHO methods
● Not endorsed by WHO ● Methods not fully transparent
● Lacked full access to results for evaluation
● Some key differences with WHO
numbers ● Revised disability weights
● No hygiene risk factor
● No disease burden from ‘improved’ water and
sanitation
GDB 2010 Study
Introduction to HWTS | 17
http://www.healthmetricsandevaluation.org/gbd
Introduction to HWTS | 18
● 1.5 million diarrheal deaths
● 89.5 million DALYs ● India 27 M
● DRC 6.4 M
● Nigeria 6.2 M
● Pakistan 5.5 M
● China 1.3 M
● Only 25% diarrheal deaths due to
poor water and sanitation ● Water and sanitation: 0.9% of DALYs
● Hygiene not included
GDB 2010 Study
Introduction to HWTS | 19
● Burden of disease from poor WASH
is high
● Diarrheal disease is a leading cause
of mortality and morbidity
● Different online resources
● Next: Microbial Water Quality
Conclusion
