Yes, RUBELLAS is a Scrabble word!

Letter values in Scrabble US: R 1, U 1, B 3, E 1, L 1, L 1, A 1, S 1.

Is it a valid word?

RUBELLAS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a contagious viral disease that is a milder form of measles lasting three or four days; can be damaging to a fetus during the first trimester

Also: german measles, three-day measles, epidemic roseola.