Rubella, sometimes called German measles or three-day measles, is a contagious disease caused by a virus. The infection is usually mild with fever and rash. Rubella usually causes a rash that starts on the face and spreads to the rest of the body with a low fever (less than 101 degrees). These symptoms last 2 or 3 days. Older children and adults may also have swollen glands and symptoms like a cold before the rash appears. Aching joints occur in many cases, especially among young women. About half of the people who get rubella do not have symptoms.