Historically, five "classical" childhood exanthems have been recognized. They include measles (rubeola), chickenpox (varicella), rubella (German measles), erythema infectiosum (fifth disease), and scarlet fever. Scarlet fever is the only exanthem that is bacterial in origin; the others are caused by viruses. Other exanthems (e.g. Duke's disease) are not considered as part of the classic childhood exanthems by some textbooks, nor are other classic childhood diseases (e.g. mumps) considered to be classic childhood exanthems as they do not typically cause rash and, to be a classic exanthem, one must be a rash- or otherwise skin disease-causing illness).
The causes of more recent additions such as roseola (sixth disease) have been identified. Vaccinations now exist against measles, rubella, and chickenpox.