Definition

     Encephalitis is an inflammation (irritation and swelling) of the brain, usually caused by infections.

Causes

• Arboviruses -- e.g., include St. Louis encephalitis, Eastern Equine encephalitis

• Herpes virus

• Mumps

• Poliovirus

• Measles

• Chicken Pox virus

• Toxins/drugs

• Reye's syndrome

• Mononucleosis

• Japanese B encephalitis

• HIV

Symptoms

• Fever

• Headache

• Stiff neck

• Double Vision

• Facial droop

• Sore throat

• Nausea/vomiting

• Stiff (spastic) paralysis

• Stupor

• Coma

• Seizures

Screening and Diagnostics

• Cerebral spinal fluid may show increased protein and increased lymphocyte count

• Blood tests (serology) may show evidence of the virus that is causing encephalitis.

• CT scans and MRI scans will show Herpes virus in the temporal lobe, or other causes such as toxoplasmosis.

Treatment

• If caused by Herpes virus -- Acyclovir intravenously

• Rabies vaccination series

• Most of the other viruses -- no specific treatment

• Mannitol may be needed to decrease intracranial pressure

• Treatment of Seizures if they occur

• Maintain airway (breathing)

Complications   

     Permanent brain damage that affects memory, speech, vision, hearing, muscle control, or sensation may occur in people who survive severe cases of encephalitis.

Prevention   

• Mosquito control -- insecticides sprayed by government agencies

• Mosquito repellents, protective clothing

• Proper childhood vaccinations

• Japanese B encephalitis vaccine available for travelers (especially high risk, children, and adults over 65 years old)