Rubella or German measles is a virus which normally only poses minor risks to the infected. That is unless you are an unborn child or a newborn baby. In newborns the virus can cause heart problems, deafness, blindness, retardation, and even death. The great news is that there is a vaccine for Rubella.
Now you can have Rubella without any of the rash, fever, headache, or joint pain normally associated with it.