Reviewed by Dr. Clement J. Cheng
Encephalitis is an inflammation of the brain, usually caused by a virus.
During a viral infection, the virus can build up in the brain, causing an inflammation of the brain cells and membranes. When white blood cells enter the brain to fight the infection, they cause brain swelling. The brain swelling can cause destruction of nerve cells, and brain hemorrhage (bleeding). Encephalitis is a serious condition that can lead to neurological impairment, brain damage, and death.
Encephalitis can be caused by a variety of viruses, transmittable through insect bites, food, or skin contact. Arboviruses, viruses that are caused by mosquito or tick bites, are responsible for a number of cases of encephalitis each year. Examples of arboviral encephalitis in the United States are West Nile Encephalitis, St. Louis Encephalitis, and Eastern Equine Encephalitis. Enteroviruses, such as poliovirus, are another common form of viral encephalitis. Other causes of encephalitis are herpes simplex infection, chicken pox or shingles, measles, mumps, rubella, rabies, and in rare cases, vaccinations.