What Is Herpes Simplex Encephalitis?
Herpes simplex
encephalitis is responsible for about 10 percent of all encephalitis cases. There are about two cases of herpes simplex encephalitis per million people per year.
This rapidly progressing disease is the single most important cause of fatal sporadic encephalitis in the United States.
Herpes simplex encephalitis can be caused by either the herpes simplex virus type 1 or herpes simplex virus type 2.
Herpes simplex encephalitis due to herpes simplex virus type 1 (which causes
cold sores or blisters around the mouth or eyes) can affect any age group but is most often seen in people under age 20 or over age 40.
About 30 percent of cases of herpes simplex encephalitis result from the initial infection with the herpes simplex virus; the majority of cases are caused by reactivation of an earlier infection.
How Is Herpes Simplex Encephalitis Transmitted?
Herpes simplex encephalitis caused by the type 1 virus is transmitted through contact with an infected person.
Type 2 virus (
genital herpes) is most often transmitted through sexual contact. An infected mother can transmit the disease to her child at birth (through contact with genital secretions), but this is uncommon.
In herpes simplex encephalitis, fever can be followed by:
- Personality and behavioral changes
- Seizures
- Partial paralysis
- Hallucinations
- Altered levels of consciousness.
Brain damage in adults and in children beyond the neonatal period is usually seen in the frontal and temporal lobes and can be severe.
In newborns, herpes simplex encephalitis symptoms generally develop between 4 and 11 days after delivery. These symptoms include:
- Lethargy
- Irritability
- Tremors
- Seizures
- Poor feeding.
