Final answer:
An acute condition is a sudden onset or a rapid worsening of a more long-standing condition, whereas a chronic condition is long-term. A disease constantly present at a steady rate in a population is called endemic.
Step-by-step explanation:
A condition of sudden onset or a more long-standing condition that has suddenly worsened is known as a acute condition. An acute disease such as influenza is short in duration, involves a rapid onset of disease conditions, and can run its course until a person recovers or, in more severe cases, leads to the person's death. This is distinct from a chronic condition, which is a long-term or lifelong condition such as type 1 diabetes or cardiovascular diseases.
A disease that is constantly present in a population is termed endemic. When speaking of epidemiology at the population level, other types of disease occurrences include epidemics, which are sudden outbreaks, and pandemics, which spread through multiple populations or worldwide.