This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
True about polioviruses is - 
Select and explain. 
A. Most cases are symptomatic, B. Spastic paralysis, C. Injectables and severe exercise increases chance of paralysis, D. Inactivated polio vaccine are given to child less than 3 years of age
C: Injectables and severe exercise increases chance of paralysis
Answer: C: Injectables and severe exercise increases chance of paralysis 
Explanation: 91-96% cases of polio virus infections results in inapparent or subclinical infection .There are no presenting complaints .Recognition only by virus isolation or rising antibody titre. In case of paralytic polio the predominant sign is asymmetrical flaccid paralysis. The primary course of immunisation consists of 4 inoculations. First 3 doses are given at interval of 1to 2 months and 4th dose 6 to 12 months after 3rd dose. IPV first dose is given when 6 weeks old.Additional doses are recommended prior to school entry and then every 5 years until 18 years Reference : Park's Textbook of preventive and social medicine, 24th edition.Pg no. 221