Encephalitis is inflammation of the brain caused by a virus.
Although a rare disease, it commonly occurs in children, the elderly or people with weakened immune systems such as those suffering from HIV/AIDS or cancer.
Encephalitis is different from meningitis, which is the inflammation of the layers (meninges) that cover the brain.
There are two major types of encephalitis -
Acute Viral Encephalitis caused by a direct attack on the brain.
Post Infectious Encephalitis, an autoimmune condition whereby the body's immune system attacks the brain following a viral infection elsewhere in the body.
Some of the signs and symptoms of encephalitis are -
Fever
Headache ranging from mild to severe
Loss of energy
Poor appetite
General sick feeling
Nausea and vomiting
Stiff neck
Convulsions
Disorientation
Problems with speech or hearing
Memory loss
Hallucinations
Drowsiness
Coma
Bulging in the soft spots (fontanels) of the skull in infants.
Aversion to bright lights
Problems with control of speech and movement.
Unusual behavior depending upon which area of the brain has been affected.
The common viruses that cause encephalitis are -
Herpes Simplex virus type 1.
Varicella Zoster virus is generally responsible for chicken pox and shingles, but could also cause encephalitis in adults and children.
Epstein-Barr virus - This virus could also cause encephalitis, in a small number of cases, it has been known to be fatal.
Mosquitoes and ticks are one of the most common causes of epidemic encephalitis.
Listed below are some of the types of mosquito-borne encephalitis -
