Yes, DENGUES is a Scrabble word!

Letter values in Scrabble US: D 2, E 1, N 1, G 2, U 1, E 1, S 1.

Is it a valid word?

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

an infectious disease of the tropics transmitted by mosquitoes and characterized by rash and aching head and joints

Also: dengue fever, dandy fever, breakbone fever.