Objective To investigate the epidemiological characteristics and etiological distribution of viral encephalitis in Hebei Province.

Methods Case information for patients diagnosed with viral encephalitis at 6 sentinel hospitals in Hebei Province from 2022 to 2023 was collected. Blood or cerebrospinal fluid (CSF) samples of the cases were obtained and tested for IgM antibodies against 10 common viruses in both serum and CSF using enzyme-linked immunosorbent assay (ELISA), and CSF samples were additionally measured for nucleic acids of 10 pathogens using real-time fluorescent quantitative polymerase chain reaction (real-time PCR).

Results From 2022 to 2023, a total of 410 cases of viral encephalitis were reported in Hebei Province, with a male-to-female ratio of 1.20∶1. Patients aged 15 or below accounted for 93.66% of the total cases. Cases were distributed throughout the year, with a relatively higher number of cases from March to July, accounting for 72.92% (299/410). Among the 410 cases, 185 samples were positive for pathogens with the detection rate of 45.12%. The most common pathogens were herpes simplex virus (27.56%), enterovirus (7.32%), and mumps virus (5.61%). Cases of encephalitis caused by herpes simplex virus mainly occured in spring, while those caused by enterovirus mostly occurred in spring and summer. Cases of mumps virus and Epstein-Barr virus (EBV) clustered in March, and cases of Japanese encephalitis virus clustered in October. The male-to-female ratio of positive cases of viral encephalitis was 1.06∶1 (95/90). These cases were predominantly concentrated in children, with the highest proportion in the 5 to <10 years old age group, accounting for 61.62% (114/185).

Conclusion Cases of viral encephalitis in Hebei Province was characterized by distinct demographic and seasonal characteristics. Pathogens exhibited significant diversity, with herpes simplex virus, enterovirus, and mumps virus being the predominant pathogens. It is recommended to continuously strengthen the etiological surveillance of viral encephalitis to provide a scientific basis for the precise formulation of clinical antiviral strategies.