8th International Workshop on Decentralized Wastewater Treatment in Asia
"From the Perspective of Japan’s Experience in Decentralized Wastewater
Management: Water-borne Diseases and Disasters"
January 21th, 2021

Mechanism of Water-borne
Diseases and Countermeasures
Dai SIMAZAKI
Dr. Eng.
simazaki.d.aa@niph.go.jp
Water Supply & Management Section
Department of Environmental HealthNational Institute of Public Health (NIPH)
Ministry of Health, Labour and Welfare
WHO Collaborating Centre for Community
Water Supply and Sanitation (JPN-51)

Leading causes of death globally2At a global level, 7 of the10 leading causes ofdeaths in 2019 werenoncommunicablediseases.
The world’s biggest killer
is ischaemic heartdisease, responsible for
16% of the world’s totaldeaths.
One of the largest
declines in the number ofdeaths is from diarrhoeal
diseases, with global
deaths falling from 2.6 M
in 2000 to 1.5 M in 2019.

WHO: Global Health Estimates - The top 10 causes of death, 2020
https://www.who.int/news-room/fact-sheets/detail/the-top-10-causes-of-deathLeading causes of deathin low-income countries3Despite the global
decline, six of the top 10causes of death in lowincome countries arecommunicable diseases.
Malaria, tuberculosis and
HIV/AIDS all remain in
the top 10. However, allthree are fallingsignificantly.
Diarrhoeal diseases are
more significant as acause of death in lowincome countries: theyrank in the top 5 causesof death.

WHO: Global Health Estimates - The top 10 causes of death, 2020
https://www.who.int/news-room/fact-sheets/detail/the-top-10-causes-of-death10 leading risk factors causing deathby income group, 2004

4

WHO: Global Health Risks - Mortality and burden of disease attributable to selected major risks, 2009https://www.who.int/healthinfo/global_burden_disease/global_health_risks/en/

Under 5 mortality compared to sanitation
coverage, 2008

5Deaths from inadequate drinking-water and sanitation
in low- and middle-income countries by region, 2012

6

Drinking-water

Sanitation

WHO: Preventing diarrhoea through better water, sanitation and hygiene, 2014
https://www.who.int/water_sanitation_health/publications/preventing-diarrhoea/en/

Transmission of pathogens
via fecal – oral routes and barriers

7

Water 1st International: Paths of disease transmission
https://water1st.org/problem/f-diagram/

Drinking-water supply/Sanitation transitions andassociated reductions in diarrhoeal disease risk
Drinking-water

8Sanitation

WHO: Preventing diarrhoea through better water, sanitation and hygiene, 2014
https://www.who.int/water_sanitation_health/publications/preventing-diarrhoea/en/

Removal and/or inactivation of pathogens
using centralized treatment technologies

9(1) Waste Stabilization Ponds

Stockholm Environment Institute: EcoSanRes Series, 2011
Microbial Exposure and Health Assessments in Sanitation Technologies and Systems
http://www.ecosanres.org/index.htm

Removal and/or inactivation of pathogens
using centralized treatment technologies

10(1) Waste Stabilization Ponds

Stockholm Environment Institute: EcoSanRes Series, 2011
Microbial Exposure and Health Assessments in Sanitation Technologies and Systems
http://www.ecosanres.org/index.htm

Removal and/or inactivation of pathogens
using centralized treatment technologies

11(2) Constructed Wetlands

Stockholm Environment Institute: EcoSanRes Series, 2011
Microbial Exposure and Health Assessments in Sanitation Technologies and Systems
http://www.ecosanres.org/index.htm

Removal and/or inactivation of pathogens
using centralized treatment technologies

12(2) Constructed Wetlands

Stockholm Environment Institute: EcoSanRes Series, 2011
Microbial Exposure and Health Assessments in Sanitation Technologies and Systems
http://www.ecosanres.org/index.htm

Removal and/or inactivation of pathogens
using centralized treatment technologies

13(3) Conventional Wastewater Treatment (incl. Activated Sludge)

Richard Stuetz,
Principles of Water and Wastewater Treatment Processes,
IWA Publishing, 2009

Removal and/or inactivation of pathogens
using centralized treatment technologies

14

Stockholm Environment Institute: EcoSanRes Series, 2011
Microbial Exposure and Health Assessments in Sanitation Technologies and Systems
http://www.ecosanres.org/index.htm

Removal and/or inactivation of pathogens
using decentralized treatment technologies

15(1) Conventional and Improved Septic Tanks

Stockholm Environment Institute: EcoSanRes Series, 2011
Microbial Exposure and Health Assessments in Sanitation Technologies and Systems
http://www.ecosanres.org/index.htm

Removal and/or inactivation of pathogens
using decentralized treatment technologies

16(1) Conventional and Improved Septic Tanks

Stockholm Environment Institute: EcoSanRes Series, 2011
Microbial Exposure and Health Assessments in Sanitation Technologies and Systems
http://www.ecosanres.org/index.htm

Removal and/or inactivation of pathogens
using decentralized treatment technologies

17(2) “Johkasou” systemJapanese Ministry of the Environment, 2019.
Night soil treatment and decentralized wastewater
treatment systems in Japan

Reduction ratios of E. coli
O157 and Salmonella
enteritidis depended
significantly on the watertemperature and BOD.
Four log reduction could
be expected to both
pathogens under water
temp. around 20 and30°C.
Higher reduction ratios
were observed underlower influent BOD.

M. Kaneko; T. Nambu; M. Tokoro, 2001.
Behaviour of pathogenic E. coli and Salmonella enteritidis
in small domestic sewage treatment apparatus (“Johkasou”)
Water Science & Technology, 43 (12), 191–193.

Summary Lack of safe drinking water and basic
sanitation still have been one of thesignificant risk factors causing death in
low-income countries.
 Multiple WASH barriers/interventions areeffective for blocking fecal pathogentransmission and reducing diarrhoeal
disease risk.
 Pathogen removal/inactivation capability
by decentralized wastewater treatment
technologies could be comparable tocentralized ones, depending operational
conditions, maintenance, etc.

18