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
Carrier stage is seen in - 
Select and explain. 
A. Polio, B. Cholera, C. Peusis, D. Plague
A: Polio
Answer: A: Polio 
Explanation: Man is the only known reservoir of polio infection. It is the mild and subclinical infection that plays a major role in the spread of infection. They constitute the submerged poion of the iceberg of disease. Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 224