While rubeola bears some resemblance to both measles and scarlet fever, and has been considered as a mild variety of one or the other of these diseases, it is now pretty generally agreed that it is an independent affection, one attack of which usually confers protection from a subsequent attack of the same disease, but not from a subsequent attack of measles or scarlet fever, while the latter, in turn, confers no protection from rubeola. The disease pursues a mild and short course, generally without serious complication or sequel, and its greatest importance resides, perhaps, in the danger of confusion between it, on the one hand, and scarlet fever and measles on the other. Some interesting facts of an etiologic and symptomatologic character noted in the course of contemporaneous epidemics of rubeola and measles, are recorded by Tobeitz1.
The epidemic of rubeola began in December, 1898, and terminated early
THE ETIOLOGY AND SYMPTOMATOLOGY OF RUBEOLA.. JAMA. 1900;XXXV(5):300. doi:10.1001/jama.1900.02460310034004