can one be infected with Naegleria fowleri by taking Steam?
N. fowleri infection can occur after nasal and sinus irrigation, swimming and other exposures to contaminated water. The infectious agent in this case is the trophozoite, not the cyst. Boiling water contaminated with this amoebae kills it, preventing infection. Though it does thrive in warm water (37 C), it doesn't survive in steam (100 C).

Despommier's Parasitic Diseases Ch. 14 discusses N. fowleri in some detail. It's also covered in Murray Medical Microbiology Ch. 82, and Cecil medicine Ch. 360. There's also useful study in The Laryngoscope on the viability of various pathogens in contaminated water after sterilization methods.