Long-lasting anti-mosquito efficacy of a commercially impregnated bed net.

Introduction Since the pioneer work of DARRIET et al. (1 984), insecticide impregnated bed nets have clearly proved their efficacy in reducing malaria transmission and morbididy (GREENWOOD & BAKER, 1993; CHO1 et al., 1995; LENGELER et al., 1996) and even overall infant mortality (BINU et al., 1996; NEVU et al., 1996), and are now considered to be an efficient tool for malaria vector control if used on a large scale (CURTIS, 1990; W O , 1993). One of the key issues for their use on a large scale is the impregnation itself (and reimpregnation), which needs technical skills and material which may not always be available m s , 1996). Some commercial companies will therefore deliver nets which are already impregnated with permethrin or deltamethrin as requested. We received a batch of such pre-treated bed nets, impregnated with Moskitul@ (deltamethrin, 25 mg active ingredient/m2), on 6 June 1992. Moskitul@ is widely used by the French army. We performed some standard bioassays which demonstrated the efficacy of the nets against Anopheles gambiue in Cameroon (unpublished observations). Some of these nets were kept in their original white opaque plastic bags for further tests. Subsequently resistance of A. gambiae to pyrethroids was clearly demonstrated in Côte d’Ivoire (ELISSA et al., 1993; CHANDE et al., in press).