| Japanese encephalitis (JE) is an acute infectious disease affecting the central nervous system caused by mosquito bites. With high mortality, even survivors have severe neurological sequelae. JE became the type B notifiable infectious disease in China since1951. Mosquito is the main transmitting vector, with pig being the demostic reservoir.JE is caused by Japanese Encephalitis Virus (JEV) which belongs to the family Flaviviridae.According to the epidemiological data from Zibo in Shandong Province and Luoyang in Henan Province, Most of the JE case happened in adults, and had high fatality rate. Therefore, we performed laboratory test based on samples collected from those cases in these two cities from June to November2010, further comprehensive epidemiological characterization of JE. At the same time, to understand the distribution and epidemiology of other viral pathogens in these two cities, laboratory analyses were conducted concerning other pathogens such as Echovirus (ECHOV), Coxsackie virus (CoxV), Herpes simplex virus (HSV) and Mumps virus (MuV).704samples (patients age between30days infant and99years old) with viral encephalitis or meningitis were collected, among which304cases are from Zibo city (305serum samples and13cerebrospinal fluid samples),400cases from Luoyang city (327serum samples and119cerebrospinal fluid samples). Three methods were used to improve the detection rate:(1) Enzyme-linked Immunosorbent Assay was used for detection of1gM antibody to JEV, ECHOV, CoxV, MuV and HSV.(2) Detections of virus nucleic acid were conducted for partial samples (3) Cerebrospinal fluids were inoculated into tissue culture BHK-21cells for virus isolation.In Zibo,112out of304samples were IgM antibody or RT-PCR positive (36.8%). The most common pathogens were Echovirus and CoxV (59cases,19.4%), followed by JEV (30cases,9.9%), MuV (15cases,4.9%) and HSV (8cases,2.6%). In Luoyang,175out of400cases were IgM antibody or RT-PCR positive (43.75%). The most common pathogens were JEV (82cases,20.1%), followed by Echovirus and CoxV (74cases,18.2%), MuV (15cases,3.7%) and HSV (4cases,1.0%). As for the nucleicacid test, JEV is tested positive in5cases (2cases in Zibo,3cases in Luoyang), EVs positive in18cases (1in Zibo cases,17cases in Luoyang).The overall incidence of JE was0.76/lakh, in Zibo,90.0%of JE cases occurred in age group>15year. Twenty five Japanese encephalitis cases (83.3%) occurred in age group＞40years, with adult JE incidences prevalent. Similarly in Luoyang, the JE incidence is1.25/lakh,90.0%of the total cases occurred in age group1-10years (31.7%) and＞40years(50%), both children and adult incidences dominating the epidemic. Overall, JE incidences among adults is increasing year by year,This research reveals the prevalence of JE among adults in Zibo and Luoyang. This study provides useful information to other countries or regions for the adult JE cases control and Prevention, as well as the specific diagnosis of viral encephalitis pathogen and pathogen distribution in China. |
