An experimental hut evaluation of PermaNet(®) 3.0, a deltamethrin-piperonyl butoxide combination net, against pyrethroid-resistant Anopheles gambiae and Culex quinquefasciatus mosquitoes in southern Benin.
PermaNet 3.0 is a long-lasting combination net with deltamethrin present on the sides and a mixture of deltamethrin and piperonyl butoxide (PBO), an oxidase synergist, on the top panel. An experimental hut trial comparing unwashed and 20 times washed PermaNet 3.0 and PermaNet 2.0, Olyset Net and a conventional deltamethrin-treated net washed three times was conducted in southern Benin. Anopheles gambiae and Culex quinquefasciatus from this area are highly resistant to pyrethroids through kdr and cytochrome P450 mechanisms. The unwashed PermaNet 3.0 killed slightly more A. gambiae (52%) than the unwashed PermaNet 2.0 (44%) (P=0.036), indicating only partial synergism of resistance. After washing there was significant loss of activity to a similar level, with PermaNet 3.0 killing 31%, PermaNet 2.0 killing 29% and the conventional net killing 26%. Blood-feeding rates were partially inhibited for unwashed PermaNet 3.0 and Olyset Net (27% inhibition). Personal protection against A. gambiae derived from PermaNet 3.0 was similar to that from PermaNet 2.0 before washing (50% vs. 47%), and after 20 washes it decreased to 30%. Against C. quinquefasciatus, no treatment killed >24% entering the huts. The synergism from unwashed PermaNet 3.0 was lower than expected, probably due to an unidentified resistance mechanism unaffected by PBO.
London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E7HT, UK. raphael.n'guessan@lshtm.ac.uk
Raphael
R
N'Guessan
Alex
A
Asidi
Pelagie
P
Boko
Abibatou
A
Odjo
Martin
M
Akogbeto
Olivier
O
Pigeon
Mark
M
Rowland
D000818:Animals; D000852:Anopheles; D001541:Benin / Q000453:epidemiology; D003465:Culex; D004351:Drug Resistance; D006798:Housing; D006801:Humans; D057148:Insecticide-Treated Bednets; D007306:Insecticides; D007846:Laundering / Q000379:methods; D008288:Malaria / Q000453:epidemiology / Q000517:prevention & control*; D009032:Mosquito Control; D009570:Nitriles; D010882:Piperonyl Butoxide; D011722:Pyrethrins; D013045:Species Specificity
D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin; D010882:Piperonyl Butoxide