The condition usually starts with sudden fever and a severe headache.
Other signs include:
- Abnormal sensitivity to light
- Nausea and vomiting
- Stiff neck and back
- Lack of energy, feeling sluggish
- Seizures or tremors (shaking)
- Personality change
- Loss of memory
- Trouble learning and understanding
- Restlessness, confused speech, confused thinking
Causes and Risk Factors
Cold sores and genital herpes, mumps, measles, chickenpox, Epstein-Barr virus, flu and German measles are possible risk factors for encephalitis. These viruses usually cause less serious illnesses, but in rare cases they can get into the brain and cause encephalitis. Another group of viruses is mainly the result of mosquito and tick bites.
Infection with the rabies virus can also cause encephalitis and is almost always fatal if not treated before symptoms show up. People who have weak immune systems, especially those with AIDS, are at higher risk for getting encephalitis from infections.