Rubella. The best way to "treat" german measles or rubella is to prevent it by being vaccinated against it and having your children vaccinated against it.
Mild illness. German measles or rubella is caused by a virus and is usually a mild illness. German measles can be dangerous when a pregnant woman gets it since the virus can cause birth defects. The best way to avoid it is to get vaccinated. Pregnant women are checked to make sure they're immune. The vaccine is not given to pregnant women since it's not known to be safe for the baby.