This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'Infectivity of chicken pox last for : \nSelect and explain. \nA. Till the last scab falls off, B. 6 days after onset of rash, C. 3 days after onset of rash, D. Till the fever subsides', 'role': 'user'}, {'content': 'Answer: B \nExplanation: “Period of communicability of varicella range from 1 to 2 days before the appearance of rash, and 4 to 5 days there after.”\nPark 18/e, p 123\nThe patient ceases to be infectious once the lesions have crusted.\nScabs are not infective. So, option “a” is wrong.\nImportant features of chicken pox :\n\nCausative Agent - Varicella zoster virus (HHV type 3)\nIncubation period - 14 to 16 days\nSecondary attack rate - 90%\nRash', 'role': 'assistant'}]