REGIONAL WORKSHOP ON REACHING THE MOST
VULNERABLE WITH HOUSEHOLD WATER TREATMENT
AND SAFE STORAGE
WATER STORAGE AND LINKS TO
VECTOR BORNE DISEASE
Bishnu Timilsina, Chief, WASH
UNICEF Lao PDR
10-13 November, 2014
Don Chan palace, Vientiane, Lao PDR
unite for children
Introduction
 Vectors transmit diseases through bites. Mosquitoes, ticks, bedbugs,
etc. are the vectors.
 These diseases are commonly found in tropical and sub-tropical
regions.
 Vector-borne diseases account for 17% of the estimated global
burden of all infectious diseases like malaria.
 Dengue -World's fastest growing vector-borne disease
 Improper storage of water at home, poor drainage and uncollected
waste in the community leading to stagnant water, is the main cause
of the increased population of vectors.
2
Lifecycle of Vectors (Mosquitos) and Related Diseases

Mosquitoes need stagnant water to breed

Mosquitoes breed, and lay eggs
throughout the warm months.

Mainly, dengue fever, chikungunya,
encephalitis, malaria, yellow fever, and
West Nile Virus (WNV) are commonly
found vector borne diseases.
3
Link with water storage
 The relatively frequent detection of faecal indicator
bacteria in rain water is not surprising, given that roof
catchments and gutters are subject to contamination
by bird and small animal droppings.
 There is no risk of dengue mosquito laying its eggs in
water kept in a pot for a day,
4
Link with Water Containers
 Most mosquitoes lay eggs that require water for
hatching. Some mosquitoes lay eggs directly on the
surface of water
 Mosquito is attracted towards water with traces of
dust in it.
 If pot is kept in the open for six days it may carry some
particles of dust and attract dengue mosquito to breed
in it.
5
Link with Water Containers
Aedes aegypti or Aedes albopictus breeds almost
entirely in man-made container habitats inside and
close to human habitation, particularly items such as
rain-filled discarded food and beverage containers,
plastic packaging, used tyres, domestic water storage
containers and any other confined, water-filled
containers.
6
Common container
Common containers in which eggs develop into adult dengue
mosquitoes
Large discarded containers (tires, damaged appliances) and small discarded containers (paint cans)
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Trash cans, pails or buckets, painting trays, toys
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Containers that are filled with water by people and also collect rain water
Water-storage containers (wells, tanks, cisterns, barrels, jars, buckets).
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Monthly distribution of Dengue Cases in Myanmar
2007 and 5-year average (2003 - 2007)
Number of Dengue Cases
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Months
2007
5-year average
8
Control Vector Breeding from Long Term Storage
 Emptying vessels more often than every 7 days
strongly reduced pupal production
 System like RWH needs longer term storage.
because it needs to balance water over year
not day or month
 Only way of delink vectors from storage is
sealing.
9
Removing breeding sites
Critical in Laos/Cam/VN conditions:
1. Remove stagnant water around the home,
turn over pots/coconuts/tins
2. When collecting rainwater: clean the gutters
as well, do not allow leaves to create stagnant
water
3. Keep tanks well covered and ensure
functioning screen in critical places
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RWH storage as breading sites
Mosquito
breeding in
RWH tank
can be
controlled by
using screen
on way from
gutter to tank
11
12
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GUIDANCE ON USE OF
RAINWATER TANKS [Australia MoH]
Rainwater tanks have been identified as potential breeding
sites for vectors of dengue virus and the WHO
recommends all tanks have screens or other devices to
prevent adult mosquitoes from emerging (WHO 1997).
In Queensland it has long been suggested that rainwater
tanks are associated with breeding of Aedes aegypti, the
primary vector of dengue virus (Kay et al. 1984). This was
confirmed in an outbreak of dengue in the Torres Strait
Islands in 1996–97 (Hanna et al. 1998). In addition, a
survey conducted in the Torres Strait Islands in 2002
detected adult mosquitoes, including Aedes aegypti, in
rainwater tanks with missing or faulty insect screens
(Ritchie et al. 2002
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WSP for RWH
NO
Hazards
1
Control
Monitoring
When
Corrective action
Roof not cleaned
4
properly of faecal
material found
Tree overhanging over 3
collection tank
Cleaning of roof
and gutter
Before
rainfall
Clean roof regularly
Tree branches do
not overhang the
roof and tank
Annual
Trim trees
3
Animal and bird
entering the tank
3
All opening on tank Annual
free from animal
and bird entry
Install and repair
inspection cover and vents
mesh
4
Tank dirty and
accumulation of
sediment
4
Tank cleaned
Annual
regularly and
disinfected annually
Clean tank regularly and
disinfect.
5
First flush of water
enter into the tank
5
First flush diversion Before
in place and used
raining
properly
Install first flush system
and train users.
2
Risk
15
WSP for RWH
NO Hazards
Risk Control
6
Unhygenic
5
withdraw of water
7
Leaching of
3
chemical in to
intake
Leakage or cracks 2
on tank
8
9
Water not filtered 2
10
Leaching of
chemical from
roof(pb, As)
Install tap or
other sanitary
means for
withdraw
No source of
chemical or set
back distance
Free from
leakage and
cracks
Filter installed
and maintained
Monitorin Corrective action
g
When
Monthly
Move contamination
source or improve
sanitary condition
At
Install tap at least 5
installation cm above base of
tank
Annual
Sanitary inspection
Annual
Install and clean
filter
Material of roof At
Material tested or
approved
installation approved
16
17
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Conclusion
 Both drinking water and unmanaged waste water can be the
causes of vector borne disease if not handled properly
 Storage tank and vessels for drinking water need to be emptied
and dried regularly within one week
 Storage tank at system level need to be covered or screen
applied to control mosquito get in to water tank
 Stagnant water around community need to be drained as part of
sanitation activities.
 Environmental Management, Chemical Control (Inseticides) and
Social Mobilization (Incl. Community Awareness) together can be
used as tools for vectors controls.
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Rain Water Harvesting
Clean Roof
Standing water
First flush/filter
Clean tank, annual cleaning
& disinfection
Thanks For Your Attention
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- International Network on Household Water Treatment