Rubella, commonly known as German measles, is a disease caused by the rubella virus. Rubella is a common childhood infection usually with minimal systemic upset although transient arthropathy (joint condition) may occur in adults who contract the virus. Serious complications are very rare, although infection of a pregnant woman by Rubella virus can be serious. If the mother is infected within the first 20 weeks of pregnancy, the child may be born with congenital rubella syndrome (CRS), which entails a range of serious illnesses. Spontaneous abortion occurs in up to 20% of cases. Apart from this scenario, rubella is a relatively trivial infection.

However, Rubella is extremely contagious. Rubella is transmitted via airborne droplet emission from the upper respiratory tract of active cases (can be passed along by the breath of people sick from Rubella). The virus may also be present in the urine, feces and on the skin. There is no carrier state, the reservoir exists entirely in active human cases. The disease has an incubation period of 2 to 3 weeks. During this incubation period, the patient is contagious typically for about one week before he develops a rash and for about one week after.

After an incubation period of 14–21 days, German measles causes symptoms that are similar to the flu. The primary symptom of rubella virus infection is the appearance of a rash (exanthem) on the face generally a pink or light red color, which spreads to the trunk and limbs and usually fades after three days (it is often referred to as three-day measles). The facial rash usually clears as it spreads to other parts of the body. Other symptoms include low grade fever, swollen glands (sub occipital & posterior cervical lymphadenopathy), joint pains, headache and conjunctivitis (eye infection). The swollen glands or lymph nodes can persist for up to a week and the fever rarely rises above 38 C (100.4 F).

Forchheimer's sign occurs in 20% of cases, and is characterized by small, red papules on the area of the soft palate (see photo).