Section 2(13) in The Indian Port Health Rules, 1955
(13)"period of incubation" means(a)in respect of a quarantinable disease mentioned below, the period specified against it.Plague .........................6 daysCholera ............................5 daysYellow fever ....................6 daysSmallpox ...........................14 daysTyphus ............................14 daysRelapsing fever ................8 days, and(b)in respect of an infectious disease such period as maybe declared by the Central Government by notification in the Official Gazette to be the period of incubation of that disease;
