Vector control issues and
new technologies
Dr Pierre Guillet
Global Malaria Programme
Vector Control and Prevention
6th Intercountry meeting of National Malaria
Programme Managers
Cairo, 3 – 6 July 2006
Vector control and prevention objectives
Vector control to be expanded using ITNs and IRS
Long-Lasting Insecticidal Nets to be used
– Obviate the need for re-treatment campaigns
– Cheaper than conventionally treated nets
Targeting full coverage as an immediate objective to
protect all populations at risk of malaria
– 1 LLIN for 2 persons at risk of malaria
– Simpler to achieve
– Plans for replacement of LLINs once exhausted
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What is a LLIN?
WHO definition
– 20 standard washes
– 3 years
2 recommended products
– Olyset & PermaNet 2.0
Life-time of a LLIN
– Polyester: 3 years
– Polyethylene: 5 years
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Olyset efficacy
Several trials concluded to good efficacy for 5 up to 7 years.
On going Tanzania multi-village trial: almost complete interruption
of transmission with both Olyset & PermaNet for more than 18
consecutive months
Efficacy against leishmaniasis vectors confirmed
CDC results: rapid loss of efficacy based on WHO test cone and
slow regeneration after washing.
– Need for standardized test methods and procedures
– Difficulty in testing efficacy of permethrin treated materials
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WHO test cones (3 minutes exposure, forced contact)
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Tunnel test (12 hours, free flying mosquitoes)
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WHO test tubes (3 minutes, forced exposure)
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Test method & efficacy of treated nettings
Deltamethrin 25 mg/m2 Permethrin 500 mg/m2
100 100
90 90
80 80
70 70
% mortality
% mortality
60 Cone 60 Cone
50 Tube 50 Tube
40 Tunnel 40 Tunnel
30 30
20 20
10 10
0 0
0 1 2 3 4 6 8 10 12 0 1 2 3 4 6 8 10 12
Washes Washes
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New LLINs under WHOPES evaluation
8 new LLINs under WHOPES testing
– Expected dates for WHO recommendation:
• Dec 06: 1 (BASF Germany)
• June 07: 4 (Tana & Netto, Thailand; Yorkool & Genfont, China)
• Dec 07 : 3 (Clark USA, Syngenta Switzerland, IIC France)
Current production capacity: 5.3 million/month with
2 producers (63.6 millions/year). Need for planning orders.
Average FOB price: 4.5 to 5.5 US $/net X-family size (1.6 W x 1.8 L x 1.5 H)
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Expected production capacity
(based on products already in WHOPES)
25
Million LLINs per month
20
15
10
5
0
Dec-06
Dec-07
Dec-08
Jun-06
Jun-07
Jun-08
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Costs for LLINs: procurement & distribution
LLINs* Price Delivery cost Programme cost
Mozambique, Olyset (5 years) US$ 5.5 US$ 1.28 US$ 0.68/pp/year
Niger, PermaNet (3 years) US$ 4.16 US$ 1.5 US$ 1
Webster et al., 2006 US$ 5.2 US$ 2.7 (4) US$ 0.8–1.32 (1 – 1.5)
* IFRC Joint LLIN/EPI campaigns, Hoyer 2006, LSHTM
Interesting developments in Africa linking ITN distribution with •
EPI activities (routine and campaigns) & ANC services
Opportunity for achieving full LLIN coverage •
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All mosquito nets to be treated
Treatment of conventional nets (new or in use)
– Development of long-lasting treatment kits (LLT kit)
– 2 LLT kits under WHOPES evaluation (expected Dec 06 Bayer &
Dec 07 Syngenta)
Achieving full insecticide coverage
– Public sector to purchase LLINs only
– National program to treat existing conventional nets with LLT kits
– Nets locally made or sold through retail market to be bundled
with LLT kits
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African Network for Vector Resistance (ANVR)
Permethrin resistance in An. gambiae s.s.
Kdr mutation East
Kdr mutation West
Kdr frequency in CAR Kdr frequency in Uganda
Data 2000 - 2005
Susceptible
West
Resistance to be confirmed
Resistant East
Highly resistant
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Selection of resistance, a fast evolving process
West Africa
– Rapid progression of kdr mutation Northward in An. gambiae M
form (central Côte d'Ivoire: from less 1 % AF in 1995 to more
than 40 % in 2003). Now present in Burkina Faso
– Rapid increase in frequency of kdr in An. arabiensis currently
observed throughout West and East Africa
Introgression of resistance genes in sibling species
Dispersal of vectors, population dynamics and gene flow,
are major factors conditioning evolution of insecticide
resistance
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Need for improved resistance monitoring
Resistance monitoring to be part of routine operational
activities. Need for:
– strengthening capacity of MNCP to implement monitoring
– national reference laboratory
– specific funding (GFATM, bilateral…)
– regional network for resistance monitoring & management
Operational impact of resistance to be assessed
Resistance management tactics (e.g. rotations) to be locally
adapted, especially for residual spraying & larval control
programs
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Threats to large scale ITN implementation
Availability of LLINs
Acceptability
Mechanisms for rapid scale-up
Pyrethroid resistance: in case of kdr, no immediate threat to
implementation but concerns in Benin
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ITNs: loss of efficacy in Southern Benin*
(experimental huts, An. gambiae)
% MORTALITY ITN: susceptible area 98
ITN: resistant area 30
Untreated net: resistant area 14
% BLOOD-FED ITN: susceptible area 3
ITN: resistant area 82
Untreated net: resistant area 82
0 20 40 60 80 100
* Data M. Rowland, LSHTM
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How to address resistance with ITNs?
Short term response:
– using non-pyrethroids to restore efficacy against resistant
vectors (Ops, carbamates?)
– tentative combination of insecticides on nets to manage
resistance
Medium term: combine ITNs (as well as IRS) with other
interventions in the context of integrated vector management
Longer term solution: development of a new insecticide
alternative to pyrethroids
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IRS: loss of efficacy in Southern Benin*
(experimental huts, An. gambiae)
% MORTALITY IRS: susceptible area 69
IRS: resistant area 31
Untreated hut: resistant area 12
% BLOOD-FED IRS: susceptible area 66
IRS: resistant area 73
Untreated hut: resistant area 88
0 20 40 60 80 100
* Data M. Rowland, LSHTM
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Insecticides for IRS: no miracle expected
DDT (residual efficacy 6 to 12 months)
– still the cheapest and easiest to use (price, residual efficacy)
– no longer used in agriculture (resistance)
– to be maintained as long as a suitable alternative is available
Pyrethroids (3 to 6 months)
– six products but equivalent to 1 as far as resistance is concerned
– not an alternative to DDT in kdr areas
Ops (2 to 3 months) & Carbamates (3 to 6 months)
– share a common resistance mechanism (modified AChE)
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New products for IRS?
Longer-lasting formulations (IVCC Gates Foundation)
– microcapsuled Chlorpyrifos-methyl (Reldan)
– bendiocarb resin based formulation (?)
Already existing contact insecticide: chlorfenapyr (pyrrole)
– different mode of action (no cross resistance with pyrethroids)
– low mammalian toxicity
– on going testing in experimental huts (ITNs & IRS)
Development of new contact insecticides (NIH, NIAID,
Gates Foundation (Grand Challenge, IVCC)
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Restoring IRS efficacy:
chlorpyrifos methyl* (experimental huts, An. gambiae)
% MORTALITY Untreated hut 12
DDT 50
lambdacyhalothrin 31
chlorpyrifos methyl 95
% BLOOD-FED Untreated hut 88
DDT 81
lambdacyhalothrin 74
chlorpyrifos methyl 85
0 10 20 30 40 50 60 70 80 90 100
* Data M. Rowland, LSHTM
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Larvicides: a range of new products
Temephos (Abate) to disappear (EU Biocide)
B. thuringiensis H 14
– Vectobac WDG & tablets for drinking water (dry formulations)
Pyriproxifen (IGR)
– Sumilarve granules (5 to 10 grams/ha, > 6 weeks efficacy)
– Slow release chips: 20 ppb, > 6 months efficacy in tanks/cisterns
Spinosins (under WHOPES evaluation)
– Spinosad, 1ppm, 3 months efficacy in closed breeding sites
(alternative to temephos?).
Novaluron (IGR) (10 to 100 grams/ha), Dinetofuran…and others
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New approaches: fumigant insecticide
Metofluthrin (SumiOne, Sumitomo)
– evaporation at room temperature
– efficacy from 1 night to 8 weeks…or more (up to 6 months?)
– safe alternative to coils. Alternative to IRS or ITNs?
– need for field testing efficacy against pyrethroid resistant strains
SumiOne matrix: 8 weeks testing in West Africa (data IRD, Benin)
Tested Mortality Feeding inhibition
Control 1177 1.1
Coil 408 84.6 96.3
Metofluthrin 534 85.6 77.6
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New products for specific applications
Insecticide incorporated
plastic sheeting (ITPS,
80 gsm, HDPE) for refugee
settings and emergencies
– 2 tarpaulins under
development:
• 1 commercial (ZeroFly
deltamethrin, Vestergaard)
• 1 experimental
(permethrin, Sumitomo)
• tents
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New products for specific applications
Insecticide incorporated plastic film
(24 gsm HDPE, 2 % permethrin)
for indoor use (wall and/or roof lining)
– On going testing in Benin (experimental
huts) and Iran (Baluchistan, village trial)
for efficacy, feasibility and acceptability.
Minimum 5 years efficacy targeted.
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New products for specific applications
Long lasting insecticide treated curtains
– Protection against domestic pests, malaria, dengue, Chikungunya
Long-lasting treated blankets for refugee settings
Wide range of possibilities & opportunities
Need for program managers to express their needs and
expectations. WHO to stimulate industry to get the right
technology for the right application.
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