I was watching the episode Macrocosm today when Neelix got sprayed with the juices from one of the viruses. After a while Neelix started to feel some of the effects of the attack. After Janeway ran the tricorder over him she said he had a high fever and fluid in his lungs. After Janeway said he had fluid in his lungs, Neelix said the word "lung" as if correcting her. That got me thinking- wasn't there an episode from an earlier season where the Vidiians took his lungs or something? Does he only have one now? From that conversation between Janeway and Neelix he seemed to be implying that he had only one.