What sort of disease is chorea?

CHOREA. A term that is used to refer to rapid, jerky, involuntary movements of the limbs or face that characterize several different disorders of the nervous system, including chorea of pregnancy and huntington's chorea (associated to dementia) as well as sydenham's chorea (associated to rheumatic fever)..
Multiple. Chorea is not actually a disease. Chorea can be a symptom of a disease that affects the nervous system. Chorea presents as "dance-like" movements affecting the arms, legs, and body. A classic presentation is sydenham's chorea, which is associated with untreated strep infections (historically called "st. Vitus' dance"). The word "chorea" derives from the greek "choreia" - meaning "dance.".