Status of pyrethroid resistance in Anopheles gambiae sensu lato

The present study confirms the presence of pyrethroid resistance among Anop heles gambiae s.l mosquitos in Gate d'Ivoire and reports the observation of such resistance in two other countries in West Africa (Benin and Burkina F aso). Malaria vector populations from Cameroon (Central Africa), Senegal (W est Africa) and Botswana (southern Africa) were found to be susceptible to pyrethroids. In the most resistant mosquito populations, resistance to perm ethrin was associated with reduced mortality, not only with respect to this compound but also towards deltamethrin. Moreover, a significant increase i n knockdown time was observed in some mosquito populations before any decre ase in mortality, suggesting that knockdown time could be a good indicator for the early detection of pyrethroid resistance. In view of the current ex tension of such resistance, there is an urgent need to set up a network in Africa to evaluate its development. it is also Vital that the impact of thi s resistance on pyrethroid-impregnated bednets be assessed.