. Neelix losing his lung - does this have ANY significance to the series? In fact is this even mentioned again in the series? I think the answer to both is "no."
Only have time to say... yes. In Macrocosm, Janeway uses a medical tricorder on Neelix after he's been stung, and she says there is fluid filling up his lungS. he corrects her and says... "Lung."
Was it's mention significant? Maybe not, but it was fun to hear the continuity.
Later for other thoughts.
I stand corrected, however, in my opinion, whether Janeway says "lung" or "lungs" is pretty trivial. What matters is whether the character (Neelix) is affected in any significant way by this major event (as any normal person would be). It could take the form of PTSD, or another form, just something that communicates to the audience that these are real people (within the universe of the show), and not Sesame Street characters.