What is encephalitis?
Ask the doctor
Q. What does it mean if a person has encephalitis? What are the symptoms?
A. Encephalitis is inflammation of the brain. It is most often caused by viruses, but other germs, such as bacteria or fungi, can cause it. In rare cases, it can be associated with autoimmune disorders or cancer.
The term encephalitis refers to the fact that the brain tissue is affected.
- If the membranes lining the brain are inflamed, but the brain itself is spared, this condition is called meningitis.
- If both the brain and lining of the brain are inflamed, doctors call it meningo-encephalitis.
The symptoms of viral encephalitis vary widely. It depends on the specific type of virus or other germ. Most commonly people with encephalitis have a headache, confusion, and fever. They can become very disoriented and lapse into a coma.
Some viral infections of the brain cause mild symptoms that you can fully recover from. The symptoms may improve in days to weeks. But in some people, full recovery takes weeks to months. Some patients do not survive, or never fully improve. During the recovery period, common symptoms may include fatigue, difficulty concentrating, tremors, and personality changes.
The type of viral encephalitis doctors always want to diagnose rapidly is herpes encephalitis. The reason is that it can be treated with the antiviral drug acyclovir. It needs to be given through an IV in the hospital. The sooner acyclovir is started, the higher the chance that the person will have a full recovery. Without treatment, there is usually permanent brain damage.
There is no treatment available for the other types of viral encephalitis.
The two viral brain infections that get the most attention in the United States are West Nile virus and eastern equine encephalitis virus (known as "triple E"). Mosquitoes carry both these viruses. The infection gets into humans by a mosquito bite.
Triple E is actually extremely rare. But if a person gets infected, the virus often causes a severe, life-threatening encephalitis. There is no specific cure.
West Nile virus infection, on the other hand, is quite common. But most people with West Nile virus have no symptoms, or feel like they have a mild case of the flu. Only rarely does the virus cause significant confusion.
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About the Author
Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
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