Epidemiologic And Etiologic Study Of Japanese Encephalitis In Henan Province

Objectives1. On the basis of the Japanese encephalitis data of our province which reported over the years, the tendency of the Japanese encephalitis of our province was analyzed.2. To capture the mosquito sample of our province in different ecological environment, we search for the dominance mosquito of our province.3. Isolation of the virus from the mosquito with the method of the cell culture, identity the virus initially with the method of PCR and the fluorescence PCR, principal for the Japanese encephalitis virus, and for the purpose of the sequence analysis of the virus, verification the type of the virus, draw the phylogenetic tress; to study and research the difference of the virus in our province with the domestic virus or overseas virus, to advance study the evolution regularity of the virus and to analyze the protection of the vaccine used at present. It provides the prevention foundation and cure countermeasure to control the Virus encephalitis.Methods1. Data collection: to statistics the Japanese encephalitis data on the basis report over the years and to reference the documents of this topic, to analyze the tendency and the cause of the Japanese encephalitis.2. Sample collection and transportation: capture mosquito in different ecologicalenvironment, to freeze to death the mosquito quickly and to reject male mosquito, classify them, 50-100 for one group, put them in tube, to seal the tube with medical adhesive tape, number then with marker pen, and put the tube in the liquid nitrogen quickly, deliver them to laboratory.3. Analysis of the constitute of the mosquito which captured in different ecological environment, to seek the dominance mosquito.4. With the methods of cell culture of BHK cell and Vero, isolate the Virus which takes along by the mosquitoes.5. Extracted the RNA with TRIZOL LS Reagent, identity the virus initially with the method of PCR and the fluorescence PCR.Result1. The incidence of the Japanese encephalitis in henan province accord to our country. From 70 era 20 century , with the apply of the Japanese encephalitis vaccine, except 90 > 91 era have a small peak, the incidence of Japanese encephalitis is descend notably. The incidence of Japanese encephalitis is to achieve 0.39/10 ten thousand. The incidence is to change with the season, above 85% case are concentrated in 7> 8^ 9 month, this coincidence to the seasonal change. The patient are distributed over the south , southeast of henna province, where the temperature is high and the rainfall is more relatively.The age distribution concentrate under ten years old mainly, more than 80%, half case are under 5 years old .The ratio of male and female near 1.4: 1.2. In this experiment, we capture 25787 mosquitoes in different ecological environment, 18999 culicines, 2715 anophelines, 85 Aedes, Armigeres 3878, The culicine hold 73.7% of the total mosquito, anopheline 10.5%, Aedes 0.3%, Armigeres 15%, it is thus clear that the culicine is dominance mosquito in henna province, the culicine is dominance mosquito in mountain area, plain and wet land, we can't capture Aedes in mountain area and plain area, but in hilly land the anopheline and Armigeres are domianance mosquito. Armigeres hold part proportion in yellow river wet land.3. By virus isolation, eight virus strains were isolated, with all causingcytopathogenic effect(CPE). the CPE of BHK cell is turn round and exfoliation, but the CPE of Vero cell is to assemble > net-balloon and turn round . 48-72 hours after infected virus, the pathological changes are occurrence, all possess filtration nature (0.22um filtration membranes), four stains of them bring to beijing for identification. After identification by PCR and fluorescence PCR, one of the rest virus is Japanese encephalitis virus possible.ConclusionIn 1953 the Japanese encephalitis virus was isolated from patient brain tissue in Henan province. In 1991, 300 culicines^ 450 Armigeres and Culex tritaeniorhynchus 30 were collected. With the methods of cell culture and infect suckling mice, one strain virus was isolated from Culex pipiens pallens. This virus was probed to be Japanese encephalitis virus by indirect immunofluorescence test and neutralization test. It was the first time to prove that the mosquito is the propagate intermediary of Japanese encephalitis in Henan province, but not to carry out the nucleonic acid sequencing and the virus identification. It was probed again that the culicine is dominance mosquito in henan province and main propagate intermediary. The virus turned to be Japanese encephalitis virus by PCR. It is the base for animal experiment n virus nucleotide sequencing and judge the virus typing. It is the foundation for analysis if the live attenuated vaccine of Japanese encephalitis having protection.