Japanese encephalitis associated acute encephalitis syndrome cases in West Bengal, India: A sero-molecular evaluation in relation to clinico-pathological spectrum

Japanese encephalitis (JE) is a major public health problem in Asia and worldwide and it is responsible mainly for viral acute encephalitis syndrome (AES). The sole etiologic agent of JE is Japanese encephalitis virus (JEV). Although JE/AES cases have been regarded traditionally as a disease of children, a growing number of patients with JE/AES cases are also seen in the adult age group every year in the state of West Bengal, India in spite of vaccination. Therefore, a systematic study was performed to differentiate and characterize the clinico‐pathological parameters and viral diversity among the patients of different age groups. Viral diversity was also evaluated from the JE/AES cases, depending on their disease severity. A total of 441 JE/AES cases were included in this study. By MAC–ELISA, 111 samples were found JEV IgM positive and among the IgM negative cases, 26 samples were found RT–PCR positive against JEV infection. Neck rigidity, abnormal behavior, convulsion, protein in CSF, WBC in CSF, and aspartate transaminase in blood differed significantly among the patients of pediatric‐adolescent and adult group in both IgM positive and RT–PCR positive cases. Viral diversity was increased significantly in the pediatric‐adolescent group compared to adult patients. Interestingly, with the rise in disease severity the viral diversity was found to be increased among the patients, irrespective of their age distribution. Based on clinico‐pathological parameters and analysis of viral diversity, it can be concluded that viral diversity which occurs naturally is likely to affect disease severity, especially in the patients of pediatric‐adolescent group. J. Med. Virol. 87:1258–1267, 2015. © 2015 Wiley Periodicals, Inc.