My wife who doesn't play a doctor on tv but does work in Nuro has a book about this.
I looked for on an online source that has the samething and Wikipedia "Naegleria fowleri propagates in warm, stagnant bodies of freshwater (typically during the summer months), and enters the central nervous system after insufflation of infected water by attaching itself to the olfactory nerve."
If you want more read here.
wikipedia org/wiki/Primary_amoebic_meningoencephalitis
Farther down in the article is "the contaminated water must be deeply insufflated into the sinus cavities for transmission to occur"
This is also mentioned in my wife's text book.
You may remember there was another Disney water park that was closed wikipedia org/wiki/Disney's_River_Country If cloudy with age memory is correct there was open water swimming in this area that was a section of Bay Lake that was closed off for swimming in the water park.
Edit sorry I don't have permissions to post links.