Investigation Of The Prevalence Of Japanese Encephalitis B In Zhaotong Prefecture, Yunnan Province

Objective: To provide the effective evidences for Japanese Encephalitis (JE) prevention andcontrol by analyzing JE epidemic data and investigating JE vectors and the dominantmosquitoes infecting JE virus(JEV) rate in Zhaotong prefecture.Contents: Collecting and analyzing JE epidemic data of Zhaotong prefecture during2005to2011; investigating mosquito component, biting human behave during night and mosquitoinfected JE virus rate in Zhaotong prefecture etc.Methods: Collecting and analyzing JE epidemic data of Zhaotong prefecture during2005to2011.The method of survey mosquito species, adult mosquitoes collection was used by lamp-trap in the pigsty of field sites overnight, and all captured adult mosquitoes were identified andcounted in the next morning, to understand fully local mosquito species compositions, thenkeeping these mosquitoes in liquid nitrogen for the further study in the laboratory; meanwhile,mosquito biting human behave during night was observed by the indoor and outdoor bednet-trap. For mosquito natural infected JEV rate, JEV was isolated by the Cell Culture(Ae.albopictus C6/36), then extracted its RNA from the infected cell, andIdentified JEV by RT-PCR and gene sequences.Results: Total of811JE cases were reported during2005to2011in Zhaotong prefecture, theyearly average of its morbidity was2.3820/100,000, of those years the highest JE incidenceswere in2006; Most of the cases were under the age of15years-group, about90.01%of totalJE cases, July to September were the peaks of JE incidences. A total114,275individualmosquitoes were collected from13species of6subgenus of4Genus, in those species Culextritaeniorhynchus, Anopheles sinensis and Armigeres subalbatus were the majorpredominant mosquitoes, their proportions were85.79%,11.85%and1.44%of total collectedmosquitoes respectively; Culex tritaeniorhynchus belonged to overnight activities mosquito species, and its peak of activity during night was between22:00-23:00;total of112groups werebe detected by C6/36cell cultures, including81groups Cx.tritaeniorhynchus,22groupsAn.sinensis,4group Ar.subalbatus and5groups Cx.pipiensquinque fasciatus, of those groups25groups were positive; in25groups5groups were isolate and identify as Flavivirus byRT-PCR, and all of them coming from Cx.tritaeniorhynchus were identified as JEV, and itsnatural infected JEV rate was0.28%。; and5JEV strains belonged to the JEV genotype-1.Conclusion: JE prevalence was serious in Zhaotong prefecture. Cx.tritaeniorhynchus was thelocal dominant species,and it was the majoy vector of JE, the natural infected JEV rate was0.28%o,and local JE epidemic may be mainly caused by JEV genotype-1,these resultssuggested that local prevention and control departments should be strengthened mosquitoescontrol measurements and vaccination inoculation should be strengthened for local susceptiblepopulation.