Epidemiological Surveillance And Etiology Discrimination Model Research On Encephalitis Syndrome

Objectives To characterize the incidence, epidemiologic characteristics, etiologic agents of meningitis and encephalitis in Guiguang,Guangxi. Strengthened the clinical diagnose capacity, strengthened the laboratory capacity to detect causes of acute meningitis and encephalitis, applying the discrimination model in distinguishing the clinical diagnose of meningitis and encephalitis. Providing guide for the further work of meningitis and encephalitis in diagnose, treatment, prevention and control.Methods An encephalitis syndrome surveillance system was established in 12 county hospitals in Guigang city. Collected the cases'epidemiologic data, blood and Cerebrospinal fluid (CSF) specimens who met the screening criteria, Enzyme-linked immunosorbent assay (ELISA) were used for detection of lgM antibody to Japanese encephalitis virus and other viral pathogens. A Fisher and Bayes discrimination model was built base on the cases'clinical symptoms and routine hospital lab results.Results During the 18-month surveillance period, a total of 867 cases who met the screening criteria of encephalitis/meningitis were evaluated, among which 42 people died, the average incidence rate was 11.52 per 100,000 and the case-fatality rate was 4.86%. Most of the cases were under 15 years old, accounting for 75.68%, 53.65% cases were in the age before to go to school. The incidence rate was decreasing following with the age increasing. The incidence rate in male was higher than in female. Most of the cases were concentrated in summer and autumn, and peaking during May to August. 93.04% of the cases came from rural areas. The cases came from Guiping city account for 41.52%, from Pingnan account for 35.99% and from Guigang account for 35.99%. 52.09% cases who met the screening criteria of encephalitis/meningitis were infected by viral pathogens. The most common pathogens were enteroviruses, mumps virus and JE virus, which account for 82.17%. The accuracy rate of clinical diagnosis(<50%) is low in viral encephalitis. For JE, 78.94% cases were detected through IgM antibody test. In cross validation, 77.5% and 67.7% of cross-validated grouped cases correctly classified by Fisher and Bayes discriminant analysis respectively.Conclusions Viral pathogen is the main causative agents of acute encephalitis/ meningitis in Guigang city. The most common pathogens were enteroviruses and mumps virus, followed by JE virus. The enteroviruses, mumps virus and Japanese encephalitis have the same epidemic peaking. The rate of JE fail to report rely on clinical diagnosis was high. Testing enteroviruses, mumps virus and JE virus IgM antibody can enhance the diagnose ability during JE season. Strengthen the mumps and JE vaccine inoculation before JE season can better control the epidemic of encephalitis/ meningitis; Fisher and Bayes discrimination model have practical value in clinical diagnosis on encephalitis/ meningitis.