The Impact of Insecticide-treated Bed Nets on Parity and Malaria Sporozoite Infectivity of Anopheles Species in Kamuli District, Uganda

ABSTRACT

Background:Themainobjectiveoftreatingbednetswithinsecticidesistoaffectthemeanlongevityofthemainvectorpopulation,andconsequentlythevectordensityandsporozoiterates.Objective:Thisstudyaimedatestablishingtheimpactofinsecticide-treatedbednets(ITNs)onthelongevityandabilitytotransmitmalariasporozoitesbythevectorspeciesasanassessmentofeffectivenessoftheITNinterventioninKamulidistrict,Uganda.Methods:Indoorhuman-bitingmosquitoesweretrappedinthreerandomlyselectedhousesintwoseparatenightsusingbattery-operatedCDClighttrapsinbothintervention(withITNs)andnon-interventionvillages(withoutITNs).Thefemaleanophelinesweredissectedandtheirparityrates andPlasmodiumfalciparumsporozoitepositivitycomparedbetweenthetwozones.AsporozoiteEnzyme-LinkedImmunoSorbentAssay,ELISA,wasusedtodetectthepresenceofP.falciparumsporozoitesintheparousvectorsinbothzones.TheparityandP.falciparumsporozoiteinfectivitywerecomparedbetweenthetwozonesusingtheKruskal-WallisranksumtestoftheR-Statisticssoftware.Results:Outofthe166Anophelesmosquitoesdissected,37.3%(19outof51)and53.9%(62outof115)wereparousintheinterventionandnon-interventionzones,respectively,indicatingthatparityofthemosquitoeswashigherinthenon-intervention(p=0.005).Infectivityofthevectorsinthenon-interventionexceededthatintheinterventionzone(p=0.032),withactivesporozoitetransmissionobservedbeforeandafterbedtimeinthenon-interventionzone.Conclusion:ResultsshowedthatITNshadimpactedonthesurvivalandconsequentlythedensityoftheoldermalariavectors,andontheirabilitytotransmitPlasmodiumsporozoites.Thiscallsforintensificationofuseofthiseffectivemalariacontrolstrategy,coupledwithbehaviouralchangecommunicationsstrategytopromotecorrectuse,aswellasuseofotherinterventionslikerepellentstoprovideadditionalprotectionespeciallybeforeandafterbedtime