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Vector control and resistance

Source: TropIKA

Title of the session: Vector control and resistance

Date: 4th November 2009

Agenda item: Scientific Session 22

Session theme: Vector control

Meeting room: Tsavo Ballroom 2

Chair(s):

• Dr./Fabrice Chandre/ Cotonou 
• Dr./Josiane Etang/Dakar

Presenters:

• Mark Paine/Liverpool School of Tropical Medicine
• Lizette Koekemoer/Vector Control Reference Unit, NICD
• Michael Green/Centeres for Disease Control and Prevention
• Charles Wondji/Liverpool School of Tropical Medicine
• Clement Kerah-Hinzoumbe/National Malaria Control Program
• James Mutunga/Virginia Tech
• Mark Rowland/London School of Hygiene & Tropical Medicine
• Simone Nikolajsen/Vestergaard Frandsen
• Samson Awolola/ Medical Research Council Laboratories, The Gambia
• Hilary Ranson/ Liverpool School of Tropical Medicine

TropIKA rapporteur: Sabina Wachira

Major topics:

• Identification of p450s involved with insecticide metabolism in anopheles gambiae
• Molecular investigations of the effect of a blood meal on insecticide resistance in anopheles funestus.
• A rapid colorimetric field test to determine levels of deltamethrin on permanet® surfaces: association with mosquito bioactivity.
• Molecular basis of pyrethroid resistance in anopheles funestus, major malaria vector in africa
• Insecticides resistance in An. gambiae from South Western Chad, Central Africa
• Highly selective carbamates towards the malaria mosquito, anopheles gambiae: design, synthesis, potency and toxicity testing.
• Pyrethroid resistance in Anopheles gambiae: sustaining malaria control using alternative insecticides
• Durable residual wall lining (dl): acceptability, durability, and performance for malaria vector management in south africa
• Insecticide susceptibility status of the malaria miosquito: anopheles gambiae s.l. 17 years after the gambian nationwide insecticide bed net impregnated program
• Insecticide resistance in African malaria vectors: protocols and results from a TDR sponsored network

Keywords:

• Insecticides
• resistance

Scope: Insecticides resistance and susceptibility

REPORT ON ORIGINAL SESSION

Overview

The resistance of malaria transmitting mosquitoes to insecticides is a concern in malaria control programmes. Over expression of P450 enzymes in the mosquitoes is responsible for the insecticide resistance. Monitoring and evaluation is a very important tools which can help to detect any insecticide resistance early enough in order to use other interventions.

CONTEXT AND ISSUE

How does resistance to insecticides develop? What is the effect of blood feeding on the mosquitoes? How do you know if your insecticide impregnated nets are no longer protective? What is the relationship between resistance and malaria transmission?

Initiatives on the ground; experience/s derived

Recombinant E. coli expression system,

A micro array method, the An. gambiae detox chip, to compare gene expression,

In vitro biochemical analysis

Research Findings

Vector surveillance and insecticide resistance monitoring should be given priority

Lessons learned

The mosquitoes are developing resistance at a high rate than the discovery of new insecticides. Research should be done on the causes of resistance as well as for new insecticides.

Issues raised, obstacles, difficulties

As resistance to insecticides spreads in Africa better control strategies should be determined through knowledge generated by research.

FINDINGS AND CONCLUSIONS

Over expression of P450 enzymes in mosquitoes is responsible for the resistance to insecticides

Rapid calorimetric field test is a simple inexpensive assay to detect effectiveness of nets; the test is effective and compares well with gold standard mosquito bioassay

Pyrethroid resistance is a major obstacle to malaria control. DNA based diagnostic test can trace metabolic résistance in field population and this is a major advance for insecticide resistant management in malaria vectors. Due to this pyrethroid resistance the use of new carbamates that are highly selective to An. gambiae acetyl-cholinesterase provides leads to developing new mosquito selective insecticides.

The network of scientists involved in insecticide resistance monitoring should assess the extent of current levels of insecticide resistance and use this information to provide guidance to malaria control programmes in the management of insecticide resistant based on the protocols developed with the support of TDR.

From open discussions/debates

Accelerate progress of development of new insecticides

Recommendations

Proposed research areas include the use of Micro array analysis and study of metabolic resistance.

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