Acyclovir for encephalitis

Herpes simplex is a virus that can cause painful blisters and sores. The virus usually affects the skin and the thin layers of tissue that moisten, lubricate and protect certain parts of the body (mucous membranes).

The two main types of herpes simplex viruses are type 1 (HSV-1) and type 2 (HSV-2). Both types of the virus can cause sores on the lips (cold sores) and sores on the genitals (genital herpes). However, HSV-1 more often causes cold sores, while HSV-2 more often causes genital sores. The viruses are transmitted by direct contact, such as touching a sore directly or through sexual contact.

A herpes infection may cause only a single outbreak of sores, but in many cases the person will have recurrent outbreaks. Recurring infections can be triggered by factors such as stress, fatigue, sunlight, or another infection, such as a cold or flu.

Treatment can reduce the number and severity of outbreaks but cannot cure the infection.

Herpes zoster, another form of herpes virus, causes chickenpox and shingles.
Acyclovir prevents herpes simplex virus—the virus that causes chickenpox, cold sores, and genital herpes—from reproducing. The medicine is given in a vein (intravenous, or IV) when used to treat encephalitis caused by these viruses.

Why It Is Used

Acyclovir is used to treat encephalitis caused by herpes simplex and varicella-zoster.

How Well It Works

To improve the chance of survival from herpes simplex encephalitis, acyclovir should be given as soon as the illness is diagnosed. The death rate from this form of encephalitis is less than 30% when prompt treatment is given, compared with 70% to 80% without treatment.

The main factors that affect the success of treatment include the age of the person and his or her level of consciousness. Confusion and disorientation (altered consciousness) are signs of encephalitis. People under age 30 and those who have a normal level of consciousness have better results than people over 30 and those who have altered consciousness.

The length of the illness also is important. In people who had the disease for 4 days or less, survival increased from 65% to 100% in those people who got acyclovir treatment. But even with treatment, serious mental and physical impairments can occur, such as paralysis, seizures, or hearing loss.

Side Effects

Side effects of intravenous acyclovir include:

    * Inflammation at the injection site.
    * Short-term increase in the creatinine level in the blood.
    * Nausea and vomiting.
    * Itching, rash, or hives.
    * Anemia.
    * Lightheadedness.
    * Headache.