Yes, I believe Neon Tetra Disease can affect other fish, esp. guppies & other tetras, not sure about others. Is he showing any other signs of illness, or did any of the others that have died? A bent spine, emaciated appearance, & faded/broken colours are signs of NTD. How long has his stripe been "cloudy" for? How long since the others died? Do post a pic if you can.