[Analysis on epidemiology and the main clinical symptoms of viral encephalitis in Gansu, 2009-2011].

Objective: To understand the epidemiological characteristics and the main clinical symptoms of viral encephalitis in Gansu.
Methods: A total of 322 viral encephalitis patients were recruited from province sentinel hospitals in Gansu province from 2009 to 2011, and their basic information were collected as well as their serum samples and cerebrospinal fluid samples. 296 out of the 322 cases were qualified for our study. Based on the patients' epidemiological characteristics and clinical features, we determined the detection of the virus types (at least one kind of virus detection was carried out for each case). ELISA was applied to test the IgM antibody of Japanese encephalitis (JE) virus (JEV), enterovirus (EV: including Coxsackie virus, echovirus, enterovirus 71), mumps virus and herpes simplex virus (HSV) in cerebrospinal fluid and serum specimen. The difference of positive detected rate between types of virus, among patients from different regions, time, or at different ages, as well as the different clinical symptoms between JE patients and other viral encephalitis patients, were analyzed and compared.
Results: The positive detected rate of virus in the 296 patients was 27.03% (80/296); the positive rate of JEV, EV, mumps virus, HSV detected was separately 7.53% (22/292), 8.75% (23/263), 13.84% (22/159) and 15.09% (40/265), and the difference was statistically significant (χ(2) = 10.849, P < 0.05). 90.91% (20/22) of the JEV positive cases were distributed in Tianshui, Longnan and Pingliang, and 95.45% (21/22) patients were infected from July to September. All the 23 EV detected positive patients were infected from April to December, while the ages of patients ranged from 1 to 44 years old. Mumps virus, HSV testing positive cases had onset every month. Logistic regression analysis showed that the patients who had the symptoms as disturbance of consciousness (OR = 15.487, 95%CI: 2.266 - 105.852), somnolence (OR = 11.659, 95%CI: 1.783 - 76.242), convulsions (OR = 11.062, 95%CI: 1.687 - 72.530) were more likely to infect JEV.
Conclusion: HSV was the principal pathogen of viral encephalitis in Gansu. An obvious central tendency in the regional and time distribution was found in JEV infection; and the clinical symptoms of JE patients were more severe.