<prompt> Measles is infective for how many days before the onset of rash -10 days4 days1 dayson same  <response>: Ans. is b i.e., 4 days Period of communicability in important respiratory infections Chicken pox: 1 - 2 days before to 4 - 5 days after appearance of rash. Measles: 4 days before to 5 days after appearance of rash. Rubella: 7 days before symptoms to 7 days after appearance of rash. Mumps: 4-6 days before symptoms to 7 days thereafter. Influenza: 1 - 2 days before to 1 - 2 days after onset of symptoms. Diphtheria: 14-28 days from disease onset. Pertussis: 7 days after exposure to 3 weeks after paroxysmal stage. 