This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
Second attack rate is minimum in - 
Select and explain. 
A. TB, B. Diphtheria, C. Measles, D. Whooping cough
A: TB
Answer: A: TB 
Explanation: Secondary attack rate is defined as the number of exposed persons developing the disease within the range of incubation period. It was initially developed to measure the spread of an infection within a family,household or any closed aggregate of persons who have had contact with a case of disease (refer pgno:100 park 23 rd edition)