It's also used to describe diseases. When describing diseases it is usually used as a phrase which describes the disease such as "acute cholecystitis" or "acute leukemia" or "acute hepatitis." When used in the context of a disease, it means the picture associated with a specific syndrome that occurs early and possibly severely which is often meant to distinguish it from a particular chronic counterpart. For example, acute hepatitis is distinguished from "chronic hepatitis." Typically, for the different viral hepatides, acute means appearing relatively quickly and lasting for a short time, as in acute hepatitis A which tends to be present soon after exposure with a fairly dramatic presentation (fever, jaundice, etc.), but usually resolves spontaneously. This can be contrasted with chronic hepatitis C which is rarely detected in the acute phase, is often symptom free and quietly causes slow damage to the liver and often does not resolve without medical treatment.