Ecolodgical studies on the transmission of Japanese encephalitis virus and efficacy of preventive vaccination

1.5个采样点健康人血液标本的中和试验显示，乙型脑炎（JE）和4种登革热（DEN）病毒抗体呈年龄相关增高，但高原地区（A、C）的阳性率明显低于邻近低地地区（B、D）、梅空河谷地区(E)和清迈河谷地区(F)，特别是DEN病毒，麻疹、风疹和1型单纯疱疹病毒IgG-ELESA阳性率无显著差异在高原和低地之间，尽管抗体流行率在采样地点之间不均匀。高原地区发现乙脑和登革病毒媒介蚊较少，而低地地区蚊群较多，E区和f区发现登革病毒媒介蚊卵数量相近。高原部分猪对乙脑病毒有igg抗体和IgM-ELISA抗体。IgM-ELISA对脑炎患者检测出32%的乙脑病例，而脑膜炎和登革出血热分别为12%和8%。在3,500名接种者中未发现明显的乙脑病例，而在3,700名未接种者中发现1例乙脑病例。

1.Neutralization test on blood specimens collected from healthy people at 5 sampling places showed age-depend- ent increase of antibodies against Japanese encephalitis(JE) and 4 types of dengue (DEN) viruses,however the rates were significantly lower at highlands (A,C) than those at the nearest lowlands (B,D),Maekong Valley lowland (E),and Chiang Mai Valley lowland (F),especially for DEN viruses,IgG-ELESA on measles,rubella and type 1 herpes simplex viruses did not show significant difference between the highlands and lowlands,although the antibody prevalence was not uniform among samplirg places.2.Very few vector mosquitoes of JE and DEN viruses were found at highlands compared with abundant mosquitoes at lowlands,and similar number of DEN vector mosquito eggs were found at E and F.3.Some of the swine at highlands showed both IgG-and IgM-ELISA antibodies against JE virus.4.IgM-ELISA on encephalitis patients detected 32% JE cases,in contrast to 12% and 8% for meningitis and dengue haemorrhagic fever cases.5.No apparent JE cases were fourd among 3,500 vaccinees in contrast to 1 JE case among 3,700 unvaccinated.