This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Which of the following increases the prevalence ofthe diseaseaEUR' 
Select and explain. 
A. Immigration of healthy people, B. Increase in cure rates, C. Decrease in the number of new cases, D. Increase in duration of disease
D: Increase in duration of disease
Answer: D: Increase in duration of disease 
Explanation: Increase in duration of disease [Ref: Park 20/e, p 58 (19/e, p 56, 57)J Prevalence refers "to all current cases (old + new) existing at a given point in time (point prevalence) or over a period of time (period prevalence) in a given population" It thus includes all the new cases, as well as those old persisting cases. It depends on 2 factors i. incidence of disease (I) ii.duration of disease (D) Thus, the longer the duration of disease, the greater its prevalence.