Incidence rate measures the frequency of new cases of a disease in a population at risk over a specified period. It is calculated as (Number of new cases during a period / Population at risk during that period) × K (where K is a multiplier, often 1,000 or 100,000). In this scenario: Number of new cases = 100 Population at risk (mid-year population is often used, but here the total population is given as 100,000) = 100,000 Incidence rate = (100 / 100,000) × 1,000 = 1 per 1,000 population. Option A (5 per 1,000) would represent the point prevalence on Jan 1, 2023 (500/100,000 * 1000). Option C (6 per 1,000) would be the period prevalence (500 existing + 100 new = 600 total cases / 100,000 * 1000).
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.