I do have one unanswered question about Troi's condition: Troi miscarried twice because of genetic damage to her reproductive structures which occurred as a direct result of her exposure to the radiation Ian was releasing. After his birth, that radiation was also strong enough to pass through a number of bulkheads and stimulate the growth of the plague samples, putting the ship in danger. Why didn't that radiation affect all of the women (and men) onboard Enterprise in addition to Deanna?
Because Troi carried the source of that radiation inside her womb for more than 36 hours. The others did not. As with many radiation effects, the strength of the effect likely diminishes rapidly over distance.