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
Carries are impoant in all the following except- 
Select and explain. 
A. Polio, B. Typhoid, C. Measles, D. Diphtheria
C: Measles
Answer: C: Measles 
Explanation: The only source of infection of measles is a case of measles. Carriers are not known to occur. There is some evidence to suggest that subclinical measles occurs more often than previously thought. Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no.160