Median incubation period means:

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