What is acute disease / illness?
acute disease / illness is A disease which is characterized by a single or repeated episode of relatively rapid onset and short duration from which the patient usually returns to his/her normal or previous state or level of activity. An acute episode of a chronic disease (for example, an episode of diabetic coma in a patient with diabetes) is often treated as an acute disease.
source: A GLOSSARY OF TERMS FOR COMMUNITY HEALTH CARE AND SERVICES FOR OLDER PERSONS. World Health Organization, 2004.