Encephalitis

Encephalitis is inflammation of the brain, usually from infection — viral most often, but also bacterial, parasitic, fungal, or autoimmune. It is a medical emergency. Early recognition and treatment save lives and brain function. India has specific endemic causes (Japanese encephalitis, dengue, chikungunya, cerebral malaria, scrub typhus) that matter.

Classic features — dial 112

• Fever with altered mental state — confusion, drowsiness, personality change.
• Headache, neck stiffness (may overlap with meningitis).
• Seizures.
• Focal neurological deficits — weakness, speech, vision.
• Unusual behaviour — increasingly recognised (autoimmune encephalitis presents this way).
• Flu-like illness progressing to confusion — seek urgent care.

Common causes in India

• Viral — Japanese encephalitis (JE; particularly UP, Bihar, Odisha, northeast), dengue, chikungunya, herpes simplex (all-India, treatable!), enterovirus, Nipah (rare), rabies (once symptoms begin, nearly always fatal — prevention through PEP after animal bite is critical).
• Bacterial and parasitic — cerebral malaria, scrub typhus, tuberculous meningitis, cysticercosis-related encephalopathy.
• Autoimmune encephalitis — anti-NMDA receptor and others — increasingly recognised; often treatable.
• Acute disseminated encephalomyelitis (ADEM) — post-infectious autoimmune.

Evaluation and treatment

• Urgent hospital: blood tests, CT/MRI brain, lumbar puncture (if safe).
• Empirical herpes-antiviral treatment as soon as herpes encephalitis is considered — starting early saves brain.
• Treat bacterial/malarial/scrub typhus specifically when identified.
• Autoimmune encephalitis — high-dose steroids, IVIG, plasma exchange, sometimes immunosuppression.
• Supportive care — airway, seizure control, cerebral pressure management, nutrition.
• Rehabilitation — long, often years; substantial recovery possible.

Prevention

• JE vaccine — free under UIP in endemic districts; catch-up if missed.
• Mosquito control — for JE, dengue, chikungunya; full-sleeved clothing, repellents, nets.
• Rabies post-exposure prophylaxis — immediate wound wash + vaccine +/- immunoglobulin after any animal bite or lick on broken skin. 100% preventable if started promptly; untreated rabies is 100% fatal once symptoms appear.
• Prompt treatment of malaria, scrub typhus, TB.
• Vaccines against measles, mumps, rubella, varicella — prevent some viral encephalitis causes.