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. Secondary encephalitis occurs when an infection starts somewhere else in the body and then travels to your brain. Encephalitis is a rare, but serious disease that can be life-threatening. You should call your doctor immediately if you notice any symptoms of encephalitis.
Source
SymptomsMost people with viral encephalitis have mild flu-like symptoms, such as:
- Headache
- Fever
- Aches in muscles or joints
- Fatigue or weakness
CausesEncephalitis 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).
Primary (infectious) encephalitis can be split into three main categories of viruses:
- Common viruses - including HSV (herpes simplex virus) and EBV (Epstein-Barr virus)
- Childhood viruses - including measles and mumps
- Arboviruses (spread by mosquitoes, ticks, and other insects) - including Japanese encephalitis, West Nile encephalitis, and tick-borne encephalitis
