Encephalitis is an inflammation of the brain that is usually caused by viruses, bacteria, or other pathogens. It presents with symptoms like headache, fever, confusion, and seizures. Risk factors include age, a weakened immune system, and living in certain geographic regions with mosquito-borne viruses. Diagnosis involves an MRI, EEG, spinal tap of cerebrospinal fluid, and blood or urine tests. Treatment depends on the severity but may include antiviral drugs, anti-inflammatory medications, fluids, and respiratory support. Prevention focuses on vaccination, insect repellent, and good hygiene.