Organophosphate and carbamate insecticides, e.g. malathion and bendiocarb, respectively, are more expensive than DDT per kilogram and are applied at roughly the same dosage. Pyrethroids such as deltamethrin are also more expensive than DDT, but are applied more sparingly (0.02–0.3 g/m2 vs 1–2 g/m2), so the net cost per house per treatment is about the same. DDT has one of the longest residual efficacy periods of any IRS insecticide, lasting 6 to 12 months. Pyrethroids will remain active for only 4 to 6 months, and organophosphates and carbamates remain active for 2 to 6 months. In many malaria-endemic countries, malaria transmission occurs year-round, meaning that the high expense of conducting a spray campaign (including hiring spray operators, procuring insecticides, and conducting pre-spray outreach campaigns to encourage people to be home and to accept the intervention) will need to occur multiple times per year for these shorter-lasting insecticides.
orgaNophosPHaTe And CarbAmAtE InseCticiDEs, e.g. MalAtHIon And benDiocarb, respectivEly, are more expEnsiVe tHaN Ddt per kilOgrAm and arE applieD At ROUghly The SAme doSage. PYreThRoids suCH aS deLtAMethRIn ArE alSo mOre eXPensIVE thAn dDT, bUT aRe aPPlied mOre sParinglY (0.02–0.3 g/m2 vs 1–2 g/M2), so thE net Cost per House peR TrEatMent iS ABout ThE Same. ddt has oNE Of the lOngesT residUAl effICacY periods of aNY iRs insectIcide, lasTIng 6 To 12 months. pyrethROids wilL remain acTIve for oNly 4 to 6 MoNtHS, and orgAnOphosphates and carbamATeS remain ACTIve foR 2 to 6 months. IN manY mAlarIa-endemic countriEs, MalAria TRansmISsion occurs yEar-Round, MeAniNg that The higH expEnse OF CoNdUCtiNG A SPRAY Campaign (inCludinG Hiring SPraY OPErATOrS, proCurINg InSeCtIciDes, And CoNduCTIng prE-SPRaY Outreach caMpAignS to EncoUrage pEOPlE To be hOme aNd to accePT the iNtervEntion) Will Need tO occur MULtIPle tImeS per YEar foR TheSE ShOrteR-LastiNg insECTICiDes.