ajuaine põletikuline haigus, mida põhjustab kas viiruste otsene tungimine ajju või viirusest põhjustatud ülitundlikkusreaktsioon, serious neurological disease caused by inflammation of the brain elements due to infection with a virus, microbe or parasite, inflammation of the brain that is caused especially by infection with a virus (such as herpes simplex, varicella zoster, or West Nile virus) or less commonly by bacterial or fungal infection or autoimmune reaction