Etiological Tests For Samples Of Viral Encephalitis In Some Areas Of China

Background Viral encephalitis is one of the most common central nervous system infections. The mortality rate is high and the sequelae is serious. It brings the human being a great threat and a heavy load. More than 130 different viral pathogens have been identified as causative agents of encephalitis. Different areas have their own etiology. In China, current surveillance system is not good enough so that the etiological character of viral encephalitis is not clear.Objective To understand the viral etiology of viral encephalitis in China by detecting IgM antibody and viral RNA of the clinical samples of some provinces of China by enzyme-linked immunosorbent assay and polymerase chain reaction.Methods 771 patients (between 4 days and 67 years of age) with viral encephalitis or meningitis were collected from six provinces of China, four blong to the high epidemic regions of Japanese encephalitis, two belong to the lower epidemic regions. Their serum and cerebrospinal fluid samples were stored at -20℃or -70℃, and transported frozen to Chinese Center for Disease Control and Prevention in Beijing for examination. Enzyme-linked immunosorbent assay were used for detection of IgM antibody to Japanese encephalitis virus, coxsackievirus, echovirus, herpes simplex virus, Epstein-Barr virus, cytomegalovirus, varicella-zoster virus, measles virus and mumps virus. The viral RNA of enterovirus and seadornavirus were detected by polymerase chain reaction.Results IgM antibody were detected in 569 of 771 (73.5%) cases. In the high epidemic regions, 496(82.4%,496/602) cases were positive, the most common pathogen was Japanese encephalitis virus (56.6%,341/602), followed by entero viruses (9.5%,57/602), mumps virus (8.8%,53/602), herpes simplex virus (6.0%,36/602), Epstein-Barr virus (0.5%,3/602), measles virus (0.3%,2/602), varicella-zoster virus (0.3%,2/602), cytomegalovirus (0.3%,2/602). In the lower epidemic regions, 71 (42.0%,71/169)cases were positive, the most common pathogen was mumps virus (17.2%,29/169), followed by Japanese encephalitis virus (12.4%,21/169), enteroviruses (6.5%,11/169), herpes simplex virus (4.7%,8/169), measles virus (0.6%,1/169), varicella-zoster virus (0.6%,l/169). And enterovirus is positive in 8 cases, seadornavirus is negative in all the cases by PCR.Conclusion According to the study, Japanese encephalitis was the most important encephalitis in China. Mumps virus was another important pathogen, especially in the lower epidemic regions. Enteroviruses and herpes simplex virus were also important pathogens. This study is one of the large-scale laboratory tests for clinical samples of viral encephalitis of China recent years. It can be the basis of developing the strategies for the prevention and control of the viral encephalitis and meningitis of China.