In a village having a population of 1000, we found patients with ceain disease. The results of new diagnostic test on that disease are as follows Test Result Disease Disease Present Absent + 180 400 - 20 400 What is the prevalence of the disease?

Prevalence is defined as all current cases (Old+New) at a given point of time Prevalence= No. of all current cases of a disease at a time/Estimated total population at that time * 100 And "Cases are those persons having the disease" (controls are healthy people, without the disease) In the given question, Test Results Present : Cases Absent: Controls + 180 400 _ 20 400 Total 200 800 Thus, Prevalence= 200/(200+800) * 100 = 20% Ref: Park 25th edition Pgno: 69