Detection and analysis of IgM antibodies against viruses in viral encephalitis and fever of unknown origin cases in Yunnan Province, China

Abstract

Objective To investigate the viral pathogens of viral encephalitis (VE) and fever of unknown origin (FUO) cases in Yunnan Province, China. Methods Serum and cerebrospinal fluid (CSF) samples of VE and FUO cases were collected to detect IgM antibody against 16 virus species, including arboviruses, enteroviruses and respiratory viruses by ELISA. Results Five hundred and twenty-six serum and CSF samples from VE cases and 221 serum samples from FUO cases were collected in Yunnan Province. The positive rates and numbers of IgM antibody against Japanese encephalitis virus (JEV), Coxsackie virus (COXV), Echovirus (ECHOV), Banna virus (BAV), Herpes simplex virus (HSV), Mumps virus (MuV), Dengue virus (DENV) and Ross River virus (RRV) in VE cases were 50.95% (268), 21.48% (113), 19.58% (103), 7.41% (39), 3.04% (16), 1.71% (9), 1.00% (5) and 0.38% (2), respectively. The positive rates and numbers of IgM antibody against JEV, DENV, HSV, BAV, MuV, COXV, ECHOV, RRV and Barmah forest virus (BFV) in FUO cases were 21.27% (47), 20.36% (45), 13.12% (29), 12.67% (28), 11.76% (26), 4.52% (10), 1.81% (4), 1.81% (4) and 0.45% (1), respectively. The main epidemic seasons of JEV, DENV, BAV, RRV and BFV were from July to October. COXV, ECHOV, HSV and MuV were from July and August. Conclusions These findings suggest that JEV was the main pathogen of VE in Summer and Autumn. COXV, ECHOV and HSV were the important pathogens of sporadic VE in Yunnan Province. DENV, BAV, HSV and MuV were the important pathogens of FUO . There were possible mosquito-borne RRV and BFV spreading in this province. Key words: Viral encephalitis; Fever of unknown origin; IgM antibody