Encephalitis is a term used to describe inflammation of the brain. This condition causes problems with the brain and spinal cord function. The inflammation causes the brain to swell, which leads to changes in the person's neurologic condition, including mental confusion and seizures. The cause of encephalitis varies depending on the season, the area of the country, and the type of exposure.
Viruses are the leading cause of encephalitis.
Although vaccines for many viruses, including measles, mumps, rubella, and chickenpox have greatly lowered the rate of encephalitis from these diseases, other viruses can cause encephalitis. These include herpes simplex virus and rabies. Encephalitis often is preceded by a viral illness such as an upper respiratory infection, or a gastrointestinal problem such as diarrhea, nausea, or vomiting. The following are the most common symptoms of encephalitis. However, each individual may experience symptoms differently.