Investigation Of The Tnosquito Vector Of Japanese Encephalitis In Mohan Port And Guanlei Port In The Border Area Of Yunnan Province

Objective: To provide the effective evidence for Japanese Encephalitis (JE)prevention and control by exploring the composition of JE vectors, populationseasonal fluctuation and JE virus (JEV) infection rate in mosquito.Methods:(1)Investigation of the species of JE vector and the ecologicalcharacteristics from May to October in2011, in the last ten days of each month,thespecies, population seasonal fluctuation and activity in night of JE vector wereinvestigated in two natural villages near Mohan Port and Guanlei Port, respectively.For survey of Mosquito vector species and populational season fluctuation was usedby lamp traps in house and pigsty of surveillance site overnight. The captured adultmosquitoes were classified, identified, counted, recorded and then deposited in liquidnitrogen with1.8ml frozen vials by different species, in order to extract and identifyvirus RNA from them in laboratory. Survey of the activity in night, the biting behaviorof mosquito during night was investigated by Human landing catches overnight, andthen the captured mosquitoes were classified, identified and recorded in the nextmorning.(2)JEV infected rate in mosquitoes Mosquito specimens were grinded, andtheir supernatant were inoculated C6/36cells, and then virus RNA wereextracted,detected and identified by RT-PCR， then JEV infected rate of differentspecies mosquito was calculated respectively.Results:(1)total of5618individual adult female mosquitoes of35species from16subgenus in10genus were collected. Of them culex tritaeniorhynchus was thedominant species of two border ports accounted for80.90%, followed by Anophelessinensis(3.67%).The survey found that there were some differences in the dominantspecies, constituent ratio and population seasonal fluctuations between the two ports. In Mohan Port, Cx.tritaeniorhynchus(85.53%), Cx.whitmorei （3.81%） andAn.sinensis（1.80%）were dominant species, and the peak of the population density ofmosquito was in May. In Guanlei Port, Cx.tritaeniorhynchus（34.06%）、An.sinensis（22.57%）、Cx.nigropunctatus（7.72%）were dominant species, and the peak of thepopulation density of mosquito was in July(16.38per light-night).In Mohan Port, thepeak of the activity of Cx.tritaeniorhynchus in night was between21：00and22：00,but in Guanlei Port it was between22：00and23：00.(2) JEV infected rate inmosquitoes Total of40pools of Cx.tritaeniorhynchus （4130），4pools ofCx.whitmorei(64),3pools of Cx.pipiensquinquefasciatus(46),1pool ofCx.pallidothorax(7),6pools of An.sinensis(100),1pool of An.vagus (39),2pools ofAn.tessellatus (45),3pools of Ar.subalbatus (73)and2pools of Ae.albopictus (69)were isolated and identified by RT-PCR, of those6pools were positives in Flavivirus,among them3pools were Cx.tritaeniorhynchus,one was An.sinensis and2ones wereAe.albopictus. One strain of JEV was isolated from Cx.tritaeniorhynchus in those6pools and its rate of infected virus was0.24‰. By its sequencing and identifying, thisJEV belonged to the JEV genotype Ⅰ.Conclusion: There are complex compositions of mosquito and numerous mosquitospecies in Mohan Port and Guanlei Port, of those species Cx.tritaeniorhynchus is thepredominant mosquito species，its rate of infected JE virus was0.24‰， which theseevident showed that Cx.tritaeniorhynchus was the main vector of JEV. These resultssuggested that local residents should be strengthened mosquito control and JE vaccineinoculation.(2) Local JE epidemic may be mainly caused by JEV genotype Ⅰ...