What is Encephalitis: Symptoms and Causes Encephalitis is an inflammation of the brain tissue. The most common cause is viral infection. In some cases it can be caused by bacteria or fungi. There are two main types of encephalitis: primary and secondary. Primary encephalitis occurs when a virus directly infects the brain and spinal cord. Symptoms Headache Fever
Aches in muscles or joints Fatigue or weakness Causes Encephalitis can develop as a result of a direct infection to the brain by a virus, bacterium, or fungus, or when the immune system responds to a previous infection; the immune system mistakenly attacks brain tissue (secondary encephalitis, or post-infectious encephalitis).