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1. Insecticide resistance monitoring and managementDr Pierre GuilletVector Control, WHO Geneva Third inter country meeting of Malaria Control Programme Managers
2. Insecticide resistance, a major problem in malaria vector control? Resistance is a serious threat to any vector control programme relying on insecticides
Continuous and successful use of DDT
Resistance in malaria vectors and agriculture
Epidemiological impact of resistance not properly documented
Impact may depend on insecticides and application methods:
Indoor residual spraying
ITNs: personal versus community protection
3. What is insecticide resistance ? Scientific definition
Operational definition
The WHO resistance monitoring system: detection of resistance using kits and diagnostic concentrations
Need for quantification of resistance
4. Resistance and cross resistance A limited number of target sites and resistance mechanisms
all pyrethroids to be seen as a single product in terms of resistance
OPs and Carbamates acting on the same target site
limited prospects for use of synergists
Only 3 classes of chemical insecticides available for IRS, two for space spraying and one for ITNs
Wider range of compounds available for larviciding
5. DDT phasing out
Need for re-registration of pesticides (FPQA, Biocide
)
New FAO/WHO joint specifications for insecticides
Re-registration of temephos, propoxur, bendiocarb
?
No new adulticide in the pipe for the next 5 years
Currently no alternative to pyrethroids for treatment of mosquito nets We are loosing our public health insecticides
6. Monitoring tools available New tools for early detection of resistance: biochemical and molecular assays now available, more sensitive than bio-assays
Biological, biochemical and molecular assays are complementary tools to detect resistance and monitor trends (R gene frequency)
Standardisation of test methods and operating procedures are essential
7. Resistance management is feasible OCP in West Africa: 15 years of successful R management through rotational use of unrelated insecticides
Housefly control in Denmark
Mexico: a 5 years demonstration project (1 pyrethroid + 1 OP + 1 carbamate)
rotation slightly better than mosaic
both rotation & mosaic much better than continuous use of a single product
no recovery of full susceptibility when resistance present at initial stage
8. Better prevent than solve resistance problems Resistance management is more effective if implemented preventively or at earliest possible stage of resistance
Expectations for implementation:
ideally, to prevent the development of resistance
alternatively, to maintain R gene frequency within acceptable limits and,
to preserve efficacy of the few insecticides still available
9. Implementing resistance monitoring and management As an integral component of any NMCP:
asses the situation in the field (distribution and impact of resistance if already present)
identify resistance mechanism(s) and their frequency
implement resistance management to prevent or slow down the development of resistance
use chemicals only where and when needed (IVM)
monitor resistance trends (gene frequency and overall resistance status)
10. Constraints & prospects for implementation Difficult when significant pressure comes from agriculture
Realistic only if alternative insecticides are available and change does not result in a significant increase in costs or toxicity
Policy makers (MOH, Finance..) does not invest on long term
Need to better inform and convince policy makers on the need for managing vector resistance
Adoption of a pre-defined strategy
Possibility for negotiating with industry packages of pre-defined interventions?
11. Collaboration with agriculture Collaboration with IRAC
regional meetings
joint WHO-IRAC Manual for avoiding vector resistance
Collaboration with Michigan State University
global mapping and dissemination of information on resistance and use of insecticides for agriculture & public health
dissemination of the Resistance Management Newsletter
12. The need for sustainable networks for resistance monitoring and management standardisation of protocols and operating procedures
training, equipment and supervision of national personnel
regional reference labs, close collaboration with academic institutions (development and transfer of new diagnostic tools, training, quality insurance
)
mapping and dissemination of information
sharing experience (at regional and inter-regional levels)
building consensus on strategies and approaches for resistance management
promoting pesticide management principles as a component of effective integrated vector management