Acute Encephalitis Syndrome (AES) is a significant cause of mortality and morbidity in children in endemic regions. While viruses have been the primary etiological agents attributed to AES in India, other microbes and toxins have also been reported in recent years. This study aimed to determine the etiology, clinical features, and outcomes of AES in children. This prospective observational study was conducted in the pediatric department of Jorhat Medical College and Hospital of Assam over a period of one year. The study included 49 diagnosed cases of AES in children aged between one month to 12 years as per the WHO case definition. Clinical features, etiology, and outcomes (recovery without or with neurological sequelae or death) were recorded for each patient. The study found that fever (100%) and altered sensorium (100%) were the most common clinical presentations in AES cases. Seizure (63%), headache (34.7%), vomiting (26.5%), diarrhea (22.4%), and other symptoms such as excessive crying and irritability (22.4%) were also observed. Japanese Encephalitis (JE) was the most common cause of AES (28.6%), followed by Herpes Simplex Virus (4.1%), pyogenic meningitis (4.1%), and tubercular meningitis (2%). The majority of cases (61.2%) were of unknown etiology. Among the 49 cases, 27 (55.1%) recovered without neurological sequelae, 8 (16.8%) had neurological sequelae, and 14 (28.6%) died during hospital treatment. The most common neurological sequelae was motor deficit (37.5%), followed by behavioral disorders and aphasia (25% each). Cranial nerve palsy was observed in one case (25%). Of the eight AES cases with neurological sequelae, five were JE positive and three were caused by other agents. The study concludes that AES cases commonly present with fever, altered sensorium, seizure, headache, vomiting, and signs of meningeal irritation. JE remains a major cause of AES in children in this region of India. These findings highlight the need for global attention to combat the menace of this arboviral encephalitis and save the lives of children.
