Define point prevalence.

• A. Number of persons ill on the date divided by the population on that date.
• B. Number of persons ill on any date divided by the population on that date.
• C. Fraction of the population having a specific disease at a given time.
• D. Number of new cases divided by the population at risk

Answer: (A)

Point prevalence is a snapshot of how common a disease is at a single, specific moment. It is calculated by counting how many people are ill on that date and dividing by the total population on that same date. This gives the proportion of the population affected right then.

Other measures describe different ideas. When you look at “ill on any date” over a defined time, that shifts to period prevalence, which covers people who have the disease at any point during that interval. Incidence is about new cases that develop over time, usually expressed as new cases divided by those at risk during the period. The phrasing that mentions a fraction having a disease at a given time is close, but the precise, widely used definition specifies the number of existing cases on that exact date divided by the population on that date, which is why this option best defines point prevalence.