258Background: The main entomological justification for use ofinsecticide-treated bed nets (ITNs)/Long Lasting Insecticide-treatedbed nets (LLINs) as the main malaria vector control method inUganda is that most biting by Anopheles gambiae sensu lato andAnopheles funestus group, the principal vectors is believed to occurbetween 10:00pm and 5:00am when most people are in bed andunder bed nets. Hypothetically, this biting pattern changed follow-ing prolonged use of ITNs/LLINs, rendering this intervention lesseffective, explaining the continued morbidity and mortality due tomalaria in endemic Uganda. A longitudinal study was conducted todetermine the Plasmodium falciparum sporozoite-infective bitinghours of the night and the parasite transmission intensities underprolonged use of ITNs/LLINs in Kamuli district.Methods & Materials: A P.f. circum-sporozoite protein ELISAwas carried out on 551 (112 pools) and 1640 (331 pools) Anophe-les gambiae s.l. and An. funestus group caught at different hours ofthe night in intervention (with ITNs) and non-intervention (with-out ITNs) zones respectively. The circumsporozoite positivity ofthe vectors was related to the time of biting humans, while theannual entomological inoculation rates (AEIRs) were obtained bymultiplying the average annual human biting rate by the sporozoiterate.Results: Results showed no impact of ITNs/LLINs on thesporozoite-infective biting hours of the night and probably reducedsporozoite infection rates. Infective biting by the vectors occurredthroughout the night, with peak infection occurring between 20:00and 04:00 hours in both zones, indicating protective effectivenessof ITNs against malaria sporozoite-infective biting by the vec-tors. In both zones, the malaria transmission potential was higheroutdoors than indoors, and was several fold higher in the non-intervention than in the intervention zone, indicating that ITNsmay have reduced the EIRs in the intervention zone. The AEIRs inboth zones exceeded one, placing Kamuli district far from malariaelimination phase like most of the countryConclusion: An integrated approach to malaria control shouldbe adopted in Kamuli district and other parts of the country toreduce the transmission intensity to levels that could interruptP. falciparum malaria transmission, and possibly driving Ugandacloser to the malaria elimination phase.