Rubella, also known as German Measles or three-day measles, is thought to be a variant of measles or scarlet fever (CDC 145). The term ôrubellaö is Latin for ôlittle redö which describes the rash caused by the rubella virus. It was first described as a separate disease in 1814 in the German medical literatures, which is where it got the name ôGermanö measles. A viral etiology for the disease was first postulated for rubella following work in monkeys, and in 1938 this etiology was confirmed by infecting children with the disease using filtered nasal washings from acute cases of rubella. Congenital rubella was first recognized in Australia in 1941 following an epidemic of the disease. Infants born to mothers infected early in their pregnancy developed congenital cataracts.
The rubella virus was first isolated in 1962, and is classified as a togavirus of the genus Rubivirus (CDC, 145). The rubella virus is an RNA virus in an envelope, and is of a single antigenic type. It does not cross-react with any other togavirus, and is related to the group A arboviruses. It is unstable, and can be inactivated by lipid solvents, trypsin, formalin, ultraviolet light, low pH and heat, and amantadine.
Rubella is transmitted through the respiratory tract , and the virus is thought to replicate in the nasopharynx and the regional lymph nodes (CDC 145). Within five to seven days after exposure, viremia occurs, and the virus spreads throughout the body. During this stage, the virus can be spread across the placenta. The fetus is damaged by destruction of cells and by cessation of mitosis. The incubation period for rubella ranges from 12 to 23 days, with an average incubation period of 14 days. Symptoms of rubella are often very mild, and may go unnoticed. The first manifestation in children is usually a rash, and rarely a prodrome. Older children and adults often have a prodrome of from one to five days in which they exh...