Aetiological study of viruses causing acute encephalitis syndrome in North West India

Acute encephalitis syndrome (AES) is a serious public health problem, caused mainly by viruses. However, the profile of viruses causing AES in Rajasthan is not well characterised.

The present study was undertaken to identify the viruses causing AES and develop diagnostic algorithm so as to help in improved diagnosis, treatment, prevention and control.

The present study is a hospital-based descriptive, observational study. Samples were processed at Grade-1 DHR/ICMR Viral Research and Diagnostic Laboratory at SMS, Jaipur.

Cerebrospinal fluid (CSF) samples were processed for IgM antibody detection by enzyme-linked immunosorbent assay (ELISA) for mumps virus (MPV), measles virus (MV), Rubella virus (RV), Japanese encephalitis virus (JEV), West Nile virus (WNV) and Dengue virus using commercial kits. Nucleic acid was extracted from CSF using automated extraction system. Real-time polymerase chain reaction was done using specific primers and probes for Herpes simplex virus (HSV), Varicella-zoster virus (VZV), Epstein-Barr virus (EBV), cytomegalovirus (CMV) and enterovirus (EV).

Statistical analysis was done using ANOVA.

Among 3088 patients, 702 (22.7%) patients were positive for one or more viruses. HSV (261;8.45%) was the most common followed by EBV (173;5.6%), VZV (97;3.1%), CMV (68;2.2%), EV (32;1.03%), MPV (27;0.9%), DV (28;0.9%), MV (19;0.6%) and RV (6;0.2%).

AES occurred sporadically in Rajasthan, samples should be tested first for herpes group of viruses followed by EV or/and for arboviruses depending on season or measles, mumps and RVs in children.