Video narration
At a community health camp, an apparently well person tests positive-does that prove disease? No. Screening is testing people without symptoms to identify those at higher risk. The first test places the person in a lower- or higher-risk group; it does not diagnose disease. If positive, the next step is a diagnostic test-a confirmatory test-before treatment. This is the turn: screening detects possible risk; diagnosis confirms disease. A negative screen lowers likelihood, but does not guarantee disease is absent. Screening also has harms: false positives can cause anxiety and unnecessary procedures, false negatives can give false reassurance, and overdiagnosis means finding disease that would never have caused harm during the person's lifetime. So a program is worthwhile only when expected benefit outweighs harm, with effective follow-up and treatment available. Back at the camp: no. A positive screening test flags higher risk, not diagnosis; confirmatory testing is needed.