"German measles" is Röteln, more properly in English rubella (vs. measles / Masern, also often confused with rubella due to some languages using "rubeola" for measles). The name also has nothing to do with Germany; it's a mistranslation of "germanus", cognate to "germane", i.e. a disease "like measles".

In other words, it's not German and it's not measles. Hopefully a lesson in using this naming pattern for diseases...