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Encephalitis is an infection of the brain characterised by fever, headache and an altered state of consciousness, with or without seizures. Most cases of encephalitis are . They may also be focal (limited to a single location) or generalised (spread throughout the brain).
Viral encephalitis may be caused by a variety of viruses including herpes simplex virus, enteroviruses, parechovirus, the rabies virus (from an animal bite), or arboviruses – those spread primarily by infected mosquitoes.
Humans are not the preferred or primary host of the arboviruses. Most people who are infected have mild to moderate symptoms. Only a very small percentage of people develop encephalitis. Throughout the world, different types of arbovirus-related encephalitis may be seen.
Viral encephalitis may also be seen as a secondary condition that occurs a few weeks after a viral illness.
, , and encephalitis are very rare. Bacterial meningoencephalitis may develop from the bacteria that cause meningitis. Tick-transmitted Lyme disease may cause bacterial encephalitis. Toxoplasma gondii, a parasite associated with cats, can cause parasitic encephalitis in some people with compromised immune systems. Other bacteria, fungi, and parasites can occasionally cause encephalitis
Last Review Date: October 13, 2016