in response to jev activity , as evidenced by human clinical cases or the seroconversion of sentinel pigs , adult mosquitoes were collected on badu island during 1995 , 1998 , and 2003 ( 6,8 , and this article , respectively ) . badu island is located at 1007s and 14209e in the central western region of the torres strait and is a granite island of 101 km ; its ecology has been described ( 68 ) . the mosquitoes were collected with centers for disease control ( cdc ) miniature light traps ( model 512 ; john w. hock co. , gainesville , fl , usa ) baited with either co2 alone or in combination with 1-octen-3-ol . mosquitoes were killed on dry ice and placed in liquid nitrogen dry shippers or on dry ice in insulated containers for transport to cairns for storage at 70c . mosquitoes were placed on a refrigerated table for species or taxonomic group identification before being placed in pools of < 200 mosquitoes and sent to queensland health forensic and scientific services or the university of queensland , brisbane , for jev detection . the virus isolation protocols used in 1995 and 1998 have been described ( 6,8 ) . in 2003 , virus rna was detected by using a real - time taqman reverse transcription  pcr ( 9 ) . to facilitate the comparison of virus distribution on badu island , trap locations were grouped into 3 general areas : within 1.2 km of the piggery , within the area of human habitation ( the community ) , and at a rubbish dump located 1.5 km from the community and 4.0 km from the piggery ( figure 2 ) . dumps are a potential focus of jev activity because mosquitoes , feral pigs , and wading birds congregate at them ( 10 ) . maximum - likelihood estimation of mosquito infection rates with 95% confidence intervals were calculated for each of these general areas by using the pooledinfrate statistical software package ( 11 ) . aerial photograph of badu island showing the location of the community , piggery , and rubbish dump . because of the difficulty in morphologically separating the members of the cx . sitiens subgroup , data for the 3 members of the group found in australia  cx . sitiens  were pooled for analysis . however , pcr restriction fragment length polymorphism analysis of a subsample of 135 cx . annulirostris was the dominant member of this group on badu island and comprised 94.1% of polymorphic specimens processed ; the other 4.4% and 1.5% were identified as cx . sitiens subgroup mosquitoes were processed for detection of jev ; 2,871 , 24,592 , and 16,865 were processed from 1995 , 1998 , and 2003 , respectively ( table ) . sitiens subgroup mosquitoes ; the highest maximum - likelihood estimation of mosquito infection rate was obtained from mosquitoes collected at the dump in 1998 . despite removal of the domestic pigs , sitiens subgroup mosquitoes collected within the community in 2003 . however , the point estimates of infection rates were lower than those obtained in 1995 and 1998 , when domestic pigs were present within the community , although the slight overlap in 95% confidence intervals indicates that this difference in infection rate was not significant . * mosquito infection rates determined by maximum - likelihood estimation ; 1995 , apr 89 and 2021 , 30 trap nights ; 1998 , mar 56 , 25 trap nights ; 2003 , mar 1319 , 92 trap nights ; ci , confidence interval ; ns , mosquitoes not sampled from this location during the year of collection . japanese encephalitis virus  positive pools detected by virus isolation or taqman reverse transcription  pcr . we demonstrated that although removing domestic pigs from areas of human habitation may reduce contact between amplifying hosts and vectors ( 7 ) , it does not eliminate the presence of jev - infected mosquitoes . indeed , evidence for low - level virus transmission to humans is provided by hanna et al . , who found a low level ( 32% ) of natural boosting immunity in badu residents who had received an inactivated mouse brain as has been observed elsewhere in the absence of pigs ( 13 ) , mosquitoes may have become infected by feeding on viremic herons and egrets , populations of which are found on badu island ( 14 ) . analysis of host feeding patterns demonstrated that birds accounted for 23% of blood meals of cx . data ) . alternately , feral pigs in the community and at the dump are a potential source of virus for mosquitoes , although < 1% of mosquito blood meals were from swine at these locations . mosquitoes could become infected by feeding on viremic pigs at the piggery and then disperse to other areas on the island . annulirostris is 4.4 km ; some females traverse up to 12 km ( 15 ) , which is considerably farther than the 2.5 km between the piggery and the community on badu island . solomon recommends that domestic pigs be moved > 5 km from human habitation to limit jev transmission to humans ( 3 ) . indeed , if infected mosquitoes were flying from the piggery to the community , then the data from our study support this recommendation . however , we suggest that domestic pigs be removed far enough away from human habitation to encompass the flight range of the local culex vectors .