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
[{'content': 'Median incubation period means: \nSelect and explain. \nA. The time required for 50% of the cases to occur following exposure., B. Time gap between onset of primary and secondary case, C. Interval between first clinical detection and final critical point, D. Time between exposure to a risk factor and subsequent development of clinical manifestations of a particular disease', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. a (The time required for 50% of the cases to occur following exposure). (Ref Park PSM 22nd/pg. 95)INCUBATION PERIOD (IP)# The time interval between contact with a risk factor (often an infectious agent) and the first clinical evidence of the resulting illness.# The time interval between invasion by an infectious agent and appearance of the first sign or symptom of the disease in question.Median incubation period: The time required for 50% of the cases to occur following exposure.# As a rule, infectious diseases are not communicable during the incubation period, except, measles, chicken pox, whooping cough and hepatitis A are communicable during the later part of IP.# Epidemiological studies are carried out for a period of twice the IP. (Hint =>5 Ps)a) Pointing the source of infection and controlb) Period of surveillance determinationc) Prophylaxis (Immunization)d) Pointing out the point source or propagated epidemicse) Prognosis estimation', 'role': 'assistant'}]