DefinitionEncephalitis is irritation and swelling (inflammation) of the brain, usually due to infections.See also: MeningitisCauses, incidence, and risk factorsEncephalitis is most often caused by a viral infection. Many types of viruses may cause it. Exposure to viruses can occur through:Breathing in respiratory droplets from an infected personContaminated food or drinkInsect bitesSkin contactIn rural areas, arboviruses -- carried by mosquitoes or ticks, or accidentally ingested -- are the most common cause.In urban areas, enteroviruses are most common, including:CoxsackievirusEchovirusPoliovirusOther viruses that can cause encephalitis include:AdenovirusCytomegalovirusEastern Equine Encephalitis VirusEpstein-Barr virusHerpes simplexinfectionMeaslesMumpsRabiesRubellaVaricella(chickenpox o