Herpes Simplex Encephalitis in Children

Herpes simplex encephalitis (also known as herpes virus encephalitis) is a serious form of brain inflammation that occurs in response to infection with the herpes simplex virus (HSV). It can affect both infants and children, and can be life threatening if not diagnosed and treated promptly.

Herpes simplex encephalitis is typically caused by HSV-1, the virus historically believed to cause oral herpes (cold sores), although the condition can also be caused by HSV-2, the virus typically responsible for genital herpes. Infants with HSV usually contract it from their mothers when they pass through the birth canal. HSV-1 can also be spread through kissing, contact with active cold sores, and sharing utensils, cups, or other items.

Because HSV remains in a person’s body for life, it can lie dormant for years without causing symptoms. If HSV reactivates and travels to the brain, it can trigger encephalitis.

Herpes simplex encephalitis can cause symptoms in infants and children such as:

• Fever
• Headache
• Lack of energy (lethargy)
• Confusion
• Behavioral changes
• Nausea or vomiting
• Sensitivity to light
• Seizures

Because herpes simplex encephalitis can be fatal if left untreated, it’s considered a medical emergency. If you think your child has herpes simplex encephalitis, contact their doctor and go to your local emergency room.

Your child’s doctor will take a complete medical history and ask whether they may have been exposed to HSV. Some of the other procedures used to diagnose herpes simplex encephalitis in children and infants include:

• CT scan of the brain, to make sure that the symptoms aren’t caused by another cause
• Lumbar puncture (spinal tap) to take a small sample of spinal fluid to look for infections
• Electroencephalogram (EEG) to see if your child is having subtle underlying seizures
• Magnetic resonance imaging (MRI) to look at detailed images that can show inflammation in the brain
• Blood tests to check for indications of infection

The key to treating herpes simplex encephalitis is early detection and treatment. Most children who are diagnosed with it are hospitalized for two weeks to a month. Sometimes children with severe cases spend time in the intensive care unit (ICU).

Children and infants with herpes simplex encephalitis are typically treated with high doses of an intravenous (IV) antiviral drug called acyclovir for about three weeks. This is usually followed by preventive oral doses of acyclovir for several months.

At Boston Children’s Hospital, we care for infants and children with herpes simplex encephalitis in our Neuroimmunology Center. The center is dedicated to the comprehensive care of children and adolescents who are affected by autoimmune and infectious disorders of the brain and spinal cord (neuroimmune disorders).