If a new curative therapy shortens the duration of illness, what will happen to the incidence of the disease?

If a new curative therapy shortens the duration of illness, what will happen to the incidence of the disease?

• A. Increase
• B. Decrease
• C. Stay the same
• D. Cannot be determined

Answer: (C)

The main idea is how incidence versus prevalence relate to illness duration. Incidence is about new infections happening over a period, while prevalence is about how many people are currently ill. If a therapy cures illness faster, it reduces how long people stay diseased, so fewer people are sick at any given time (prevalence goes down). But the rate at which new people become ill (incidence) depends on factors like exposure and transmission, not how long existing cases last. If the therapy doesn’t change how likely people are to get infected, the number of new cases per time remains the same. So the incidence stays the same.

The main idea is how incidence versus prevalence relate to illness duration. Incidence is about new infections happening over a period, while prevalence is about how many people are currently ill. If a therapy cures illness faster, it reduces how long people stay diseased, so fewer people are sick at any given time (prevalence goes down). But the rate at which new people become ill (incidence) depends on factors like exposure and transmission, not how long existing cases last. If the therapy doesn’t change how likely people are to get infected, the number of new cases per time remains the same. So the incidence stays the same.