Yes, LYSSAS is a Scrabble word!

Letter values in Scrabble US: L 1, Y 4, S 1, S 1, A 1, S 1.

Is it a valid word?

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

an acute viral disease of the nervous system of warm-blooded animals (usually transmitted by the bite of a rabid animal); rabies is fatal if the virus reaches the brain