ENCEPHALITIS, VIRAL

General Information

DEFINITION--An acute inflammation involving the brain caused by a viral infection. The viral infection may cause encephalitis as a primary disorder or as a secondary complication following viral disorders such as measles, chickenpox, rubella, vaccinia and other less known viruses or a smallpox vaccination.

BODY PARTS INVOLVED--Brain; sometimes meninges (membranes that cover the brain).

SEX OR AGE MOST AFFECTED--Both sexes; all ages.

SIGNS & SYMPTOMS

Mild cases:

• No symptoms (sometimes).
• Fever.
• General ill feeling.

Severe cases:

• Vomiting.
• Headache.
• Stiff neck.
• Pupils of different size.
• Unconsciousness.
• Personality changes.
• Seizures.
• Occasional weakness or paralysis of an arm or leg.
• Double vision.
• Speech impairment.
• Hearing loss.
• Drowsiness that progresses to coma.

CAUSES

> Viruses that cause other illnesses, including: polio; herpes; measles; mumps; chickenpox; infectious mononucleosis; infectious hepatitis; German measles; smallpox; Coxsackie virus; echovirus diseases; and Eastern & Western equine virus.

• Viruses carried by mosquitoes or other insects.
• Lead poisoning.
• Vaccine reactions.
• Leukemia.

RISK INCREASES WITH

• Newborns and infants.
• Adults over 60.
• Illness that has lowered resistance.
• Crowded or unsanitary living conditions.
• HIV or AIDS.

> Consult your doctor for treatment of any infection in your body--especially those mentioned as causes--

to attempt to prevent the spread of infection.

• Use insect repellent and mosquito netting if you travel to an area of risk.

What To Expect

DIAGNOSTIC MEASURES--

• Your own observation of symptoms.
• Medical history and physical exam by a doctor.
• Laboratory studies of blood and cerebrospinal fluid, skull x-ray, electroencephalography (studying the brain by measuring electric activity ["brain waves"]).

APPROPRIATE HEALTH CARE

• Doctor's treatment.
• Hospitalization, care in an intensive care unit (worst cases only).
• Self-care after diagnosis or hospitalization.

POSSIBLE COMPLICATIONS--A very small percentage of patients suffer permanent brain damage that impairs mental or muscle functions.

PROBABLE OUTCOME--Mild viral encephalitis is common and may go unnoticed. Severe cases usually require hospitalization. Complications and fatalities from encephalitis are most common in infants and the elderly. People in other age groups usually recover completely. Unless the attack is severe, you can expect full recovery within 2 to 3 weeks.

How To Treat

GENERAL MEASURES--

• Susceptible individuals should avoid contact with the patient.
• The illness can be frightening, both to the patient and to the family. Most hospitals have social workers who are there for your support.

MEDICATION--Your doctor may prescribe:

• Acetaminophen for headache and fever.
• Antiviral drugs, such as acyclovir or amantadine.
• Cortisone drugs to suppress inflammation (rare).
• Drugs to control seizures if needed.

ACTIVITY--You will need bed rest in a darkened room. After a 2- to 3-week recovery, you should be as active as your strength and feeling of well-being allow.

DIET--No special diet.

Call Your Doctor If

• You have any symptoms of encephalitis.
• Fever.
• New, unexplained symptoms develop. Drugs used in treatment may produce side effects.