Investigation Of Epidemiological Situation Of Dengue Fever In The Part Of Border Areas Of Myanmar

Objective:To investigate the dengue vectors distribution and composition,natural carrying rate of dengue virus,dengue virus serotype and dengue virus IgG antibody level of local healthy population in the part of border areas Myanmar,neighboring to Yunnan province of China,providing the evidences for formulating effective dengue prevention and control measurements in border areas of Myanmar.Methods:One field investigation site was selected from in Xiao Mengla of the 4th Special Zone of East Shan State and Nan Deng of the 2nd Special Zone of Shan State of Myanmar,in adjacent to Yunnan province respectively,and their longitudes,latitudes and altitudes data were collected by GPS.Venous blood(3-5milliliter)of healthy people was collected from residents in the investigation sites,centrifuging them to serum,then marking,recording coding and storing them in a refrigerator at-20? condition,and dengue virus IgG antibody was tested by Enzyme-Linked Immunosorbnent Assay(ELISA).In the clinics and township hospitals of field sites,venous blood(3-5milliliter)was collected from suspected dengue fever,centrifuging them to serum,then marking,recording coding and storing them in a refrigerator at-70? condition,in laboratory the virus was isolated by inoculating C6/36,tested and indentified by RT-PCR.In Xiao Mengla,mosquito adults were captured from human dwelling places by using eclectic mechanical aspirator in the daytime,and in Nan Deng,mosquito adults were collected from human dwelling places,animal shelters by mosquito lamp traps,all above collected mosquitoes were identified,counted,recorded,then stored them in liquid nitrogen tanks according to different mosquito species respectively,in laboratory the virus was isolated from mosquito collected from field sites by inoculating C6/36,tested and indentified by RT-PCR.Results:A total of 443 serum samples were collected from healthy people(including 180 samples from Xiao Mengla and 263 samples from Nan deng Deng),49 samples were DENV IgG positives(the positive rate 11.06%),of those 28 samples were come from Nandeng(its positive rate of DENV IgG 10.65%,28/263),and the other 21 positives from Xiao Mengla(its positive rate of DENV IgG 11.67%,21/180),and by comparing their healthy people DENV IgG positives in both field sites,there was no signification P>0.05);One cytopathic effect was obtained from 23 serum samples of suspected dengue fever patients,and was identified as dengue virus serotype 1.A total of 1516 adult mosquito individuals were captured from 22 species in 6 genera,of those the top 10 species were Anopheles sinensis(40.17%,609/1516),Culex tritaeniorhynchus(10.82%,164/1516),Aedes aegypti(9.83%,149/1516),Aedes aegypti(7.65%,116/1516),Aedes albopictus(7.32%,111/116),Culex quinquefasciatus(7.32%,111/1516),Anopheles multilocularis(4.68%,71/1516),Anopheles minimus(3.89%,59/1516),Anopheles pseudo-Willis(2.11%,32/1516)and Anopheles Willis(1.72%,26/1516),and the other 12 species were less t-han 1.00%.Of those,622 adult mosquitoes individuals of 6 species in 4 gene-ra were collected by eclectic mechanical aspirator in the daytime,and dengue vector,both Aedes aegypti and Aedes albopictus belonged to local dominant species,accounting for 18.65%(116/622)and 17.85%(111/622)of the total of mosquitoes captured respectively,the second were Armigeres subalbatus(16.56%,103/622)and Anopheles sinensis(16.24%,101/622),and followed by Japanese encephalitis vectors Culex tritaeniorhynchus and Culex quinquefasciatus were 15.27%(95/622)and 15.43%(96/622)respectively-For mosquito lamp traps overnight,a total of 894 mosquito individuals of 20 species in 4 genera were collected,of those the malaria vector Anopheles sinensis was the local dominant species,its accounting for 56.76%(508/894)of the total of mosquitoes capturing,followed by Anopheles multicularis(7.94%,71/894),Culex tritaenior-hynchus(7.72%,69/894),Anopheles minimus(6.60%,59/894)and Armigeres subalbatus(5.15%,46/894).5 cytopathic effects were obtained from 1516 mosquito samples,and identified as 3 strains of Banna viruses,2 strains of unknown viruses but no dengue virus.Conclusions:The serum antibody level of dengue virus was relatively high for the healthy people in the border areas of Myanmar,hinting its high prevalence of dengue fever;dengue vectors both Aedes aegypti and Aedes albopictus were widely distributed in the border areas of Myanmar,showing its high risk of dengue epidemic,dengue virus serotype 1 was probable local main dengue virus serotype,above results were suggested that relevant departments of Myanmar should strengthen the surveillance for dengue vector and case,preventing from dengue outbreak.