WASH Cluster – Emergency Training
VC
Vector Control Methods
Module 3A
Introduction
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WASH Cluster – Emergency Training
VC
Decision to carry out vector Control
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WASH Cluster – Emergency Training
VC
Common Vectors and their control
• Regular assessment needed for immediate control
• Must identify vector and understand life cycle for
effective control.
• Distinguish – and prioritise - between disease risk
and nuisance
• Use environmental controls where possible
• Only use chemical spraying as last resort, as
– Frequent use causes resistance
– Can be poisonous
– Environmentally polluting
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WASH Cluster – Emergency Training
VC
Planning a vector control campaign
• Strategy
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Identify vector with certainty
Determine environmental factors involved
Map breeding sites & population spread
Assess risk of disease epidemic
• Determine objectives – acceptable levels
and control methods
• Determine indicators by which to measure the impact
of the campaign
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WASH Cluster – Emergency Training
VC
Vector control campaign: Strategy
• Identify vector with certainty
• Determine environmental factors involved:
• Breeding sites
• Feeding areas
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Map breeding sites & population spread
Assess risk of disease epidemic
Determine any chemical resistance of vectors
Plan areas to be covered by campaign
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WASH Cluster – Emergency Training
VC
Vector control campaign: Objectives
Environmental controls alone?
Hygiene promotion campaign?
Chemical response needed?
A combination may be the optimum solution
to reduce the risk of epidemics
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WASH Cluster – Emergency Training
VC
Vector control campaign: Indicators
Targeted Animal Example Indicator
mosquitoes
black-flies
bugs
sand-flies
ticks
flies
lice
fleas
scabies / mites
number of specimens collected per room (captured with pyrethrum)
number of specimens collected per person per night (night-time
capture on human bait)
number of specimens collected per person per day (daily capture on
human bait)
percentage of houses infested
number of specimens collected per trap (oiled-papers or light traps)
number of specimens collected on sweeping cloth
number of specimens collected per time unit on a standard grill
percentage of persons found positive on inspection
number of specimens per trap (light and/or carbon dioxide)
percentage of specimens found positive on inspection
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WASH Cluster – Emergency Training
VC
Vector control campaign:
Planning the programme
Before implementing control measures, ensure:
• Objectives are clearly defined
• Control method options are clearly defined
• Host country regulations & role understood
• Sufficient resources & personnel
• Supervision & training requirements met
• Logistics arranged
• Role of affected community clarified
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WASH Cluster – Emergency Training
VC
Example vector control campaign
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Source: UNHCR, 1997.
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WASH Cluster – Emergency Training
VC
Example vector control campaign
• Divide area into operational zones small enough
to be treated by a team (4-5 people)
• One worker can use 8-10 hand-sprayers a day,
each containing 8 litres of solution
• With an application rate of 40 ml of solution per
m2, one worker can treat about 1,800 m2 a day,
or 36 dwellings of 50 m2 each.
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WASH Cluster – Emergency Training
VC
Vector control practical
Exercise 1:
Calculate the amount of permethrin (50%
EC formulation) needed to impregnate
200 mosquito nets with a dose of 0.2
g/m2. The net dimensions are 2m height
by 2m length, and 1m width, with an
overlap band of 0.3m width.(N.B. EC =
emulsifiable concentrate, to be diluted
with water).
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WASH Cluster – Emergency Training
VC
Vector control practical
Exercise 2:
In a malaria outbreak in a tented camp area, your
cluster has decided to treat all the dwellings with a
residual spraying of pyrethroid compound to
reduce the mosquito population. You need to
spray 1500 shelters with deltamethrin, which is
provided in a 2.5% WP (wettable powder)
formulation. The shelters have an average surface
area of 75m2. Calculate the amount of
deltamethrin and the quantity of water needed.
(N.B. 0.04 l/m2 solution is a standard coverage
value for spraying insecticide).
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WASH Cluster – Emergency Training
VC
Summary & conclusions
• Wrap-up session
• Outstanding Issues
• Sources of further information
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WASH Cluster – Emergency Training
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Terms for how vectors behave:
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Anthropophilic: bite humans
Zoophilic: bite animals
Endophagic: bite indoors
Exophagic: bite outdoors
Endophilic: rest indoors after a blood meal
Exophilic: rest outdoors after a blood meal
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WASH Cluster – Emergency Training
VC
Information needed for design of prevention
strategies:
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Vectors and their behaviour
Is there a risk of an outbreak?
Who are the most at risk?
Feasibility (security, access, funding, available materials,
adequate human resources, local capacity)?
People’s behaviour (mobile/fixed, sleep inside/outside
etc)?
Type of shelter used?
Strong preferences/dislikes?
Previous experiences
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WASH Cluster – Emergency Training
VC
Which intervention is the most
cost effective?
• IRS is much cheaper for one off interventions.
• Must repeat IRS every 6-10 months in area of
constant, high transmission
• Over 2 years it may be cheaper to use ITNs and
the families will have a greater level of control
and responsibility.
• For refugees and IDPs use of insecticide treated
plastic sheeting can be effective and economical
as it provides shelter and control of malaria
mosquitoes and flies
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WASH Cluster – Emergency Training
VC
Challenges to controlling VBDs in
emergencies:
• Efficacious tools
• Ensuring access to efficacious tools for prevention
and treatment
• Acceptability - a major key to effectiveness of the
tools
• Suitability - there on time & fit
• “Know How” to use correctly
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WASH Cluster – Emergency Training
VC
Current wisdom for main VBD control
• Early detection and confirmatory diagnosis
• Effective treatment
• Intermittent preventative malaria treatment (IPT) of
Pregnant women
• Long lasting insecticide treated nets (LLINs) to protect
from vector bites (malaria, filariasis + leishmaniasis)
• Indoor Residual Spaying (IRS) of dwellings to kill
resting insect vectors (malaria and rift valley fever)
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WASH Cluster – Emergency Training
VC
• Larvicide to kill larval forms of vectors in
surface water breeding sites (dengue and
malaria)
• ITPS to provide duel protection (shelter
and LL IRS) for displaced families (malaria
and flies)
• Tsetse fly traps (sleeping sickness)
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