Causes. The exact cause of encephalitis is often unknown. But when a cause is known, the most common is a viral infection. Bacterial infections and noninfectious inflammatory conditions also can cause encephalitis. There are two main types of encephalitis: Primary encephalitis. read more
Infectious causes of meningitis and encephalitis include bacteria, viruses, fungi, and parasites. For some individuals, environmental exposure (such as a parasite), recent travel, or an immunocompromised state (such as HIV, diabetes, steroids, chemotherapy treatment) are important risk factors. read more
The Powassan virus is a rare cause of encephalitis. Bacterial and other. It can be caused by a bacterial infection, such as bacterial meningitis, or may be a complication of a current infectious disease syphilis (secondary encephalitis). read more
Encephalitis is an acute inflammation of the brain. The majority of cases are caused by either a viral infection or the immune system mistakenly attacking brain tissue. In the United States, encephalitis is responsible for an estimated 19,000 hospitalizations, 230,000 hospital days, and $650 million in hospitalization costs. read more