CHILDREN AND ADULTSMan is the only host. Rubella virus is spread via an aerosol route and occurs throughout most of the world although endemic rubella, like measles, has been eliminated in North America.The initial site of infection is the upper respiratory tract. The virus replicates locally (in the epithelium, lymph nodes) leading to viremia and spread to other tissues. As a result the disease symptoms develop. Rash. if it occurs, (table 1) starts after an incubation period of approximately 2 weeks (12 to 23 days) from the initial infection. There is probably an immunological basis for the rash (since it occurs as antibody titers rise).

• low grade fever (less than 101F, 38.3C)
• sore throat
• Some individuals (especially adults and especially women) get arthralgia and sometimes arthritis which usually clears up in a few weeks.

In about half of all rubella infections there are no noticeable symptoms.Recovery
T-cell immunity plays an important role in recovery. IgM may persist for up to a year. There are also IgG, IgA responses. Complications
Complications are extremely rarely (1 in 6000 cases). Rubella encephalopathy (headache, vomiting, stiff neck, lethargy, convulsions) may occur about 6 days after rash. It usually lasts only a few days and most patients recover (no sequelae). If death occurs, it is within few days of onset of symptoms.Other rare complications include orchitis, neuritis and panencephalitis.
Angiocardiogram showing the pulmonary arterial tree. There is a region of constriction, also called stenosis, of the right pulmonary artery, which was due to a case of congenital rubella. CDC
Child operated on at age 3 days to correct congenital glaucoma, due to a case of congenital rubella. Note that the baby’s left eye also displayed the cloudiness associated with a congenital rubella cataract, and can be compared to the normal appearance of the right eye.
CDC/ Dr. Andre J. Lebrun
Congenital rubella cataract.
CDC/ Dr. Andre J. Lebrum Rubella cases in the United States CDCFETUSThe risk to a fetus is highest in the first few weeks of pregnancy and then declines in terms of both frequency and severity, although there is still some risk in second trimester. The virus infects the placenta and then spreads to the fetus. In an outbreak of rubella in the United States in the mid 1960's, there were over 12 million cases of rubella and 20, 000 cases of congenital rubella syndrome. If non-immune mothers are infected in the first trimester, up to 80% of neonates may have devastating sequelae. However, as the result of an excellent vaccine, there have been no cases of congenital rubella syndrome in the United States in recent years.The sequelae of congenital rubella syndrome are: