Acute Encephalitis Syndrome (AES) is a group of Clinical neurologic manifestation caused by wide range of viruses, bacteria, fungus, parasites, spirochetes, chemical and toxins. The most common causes of acute viral encephalitis are Japanese encephalitis virus, West Nile virus (WNV), Eastern equine encephalitis virus (EEEV), Western equine encephalitis virus (WEEV), Venezuelan equine encephalitis virus (VEEV), Hendra virus (HeV), enteroviruses (ENV), Chandipura virus (CHPV), Nipah (NiV), Kyasanur forest disease (KFD), St. Louis encephalitis virus, Herpes simplex, poliovirus and measles virus. AES is reported mainly from Assam, Bihar, Karnataka, Uttar Pradesh and Tamil Nadu which contributes approximately 80% of cases. The case fatality and morbidity is very high. Japanese encephalitis (JE) is considered as a main viral aetiology of patients with AES. Infection with Japanese encephalitis virus may cause febrile illness, meningitis, myelitis or encephalitis, and is clinically indistinguishable from other causes of an acute encephalitis syndrome (AES). In the year 2006, West Nile (WN) virus emerged as another cause of acute encephalitis syndrome in India. Leptospirosis and toxoplasmosis is a zoonotic disease and its severe form can cause AES. The causative agent of the AES varies with season and geographical location. The outbreak of AES and JE usually coincides with the monsoon and post monsoon period when the density of mosquitoes increases. Encephalitis due to entero-viruses occurs throughout the year as it is water borne disease. Most of the times, it may be difficult to differentiate Japanese Encephalitis from those caused by other bacteria and viruses, as clinical signs of JE are indistinguishable from other causes of AES. Under such conditions laboratory confirmation is essential for accurate diagnosis of AES. Specific anti-viral drug for AES including Japanese Encephalitis is not available till date and cases are managed symptomatically and supportive treatment plays major role.
Acute Encephalitis Syndrome, Japanese encephalitis, WNV, Nipah Virus, VEE, Leptospirosis, Diagnosis, Treatment