Yes, HOOKWORM is a Scrabble word!

Letter values in Scrabble US: H 4, O 1, O 1, K 5, W 4, O 1, R 1, M 3.

Is it a valid word?

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

parasitic bloodsucking roundworms having hooked mouth parts to fasten to the intestinal wall of human and other hosts
infestation of the intestines by hookworms which enter the body (usually) through the skin

Also: hookworm disease.