The stuffy nose and mucus are IMMUNE system reaction to a flu. It is the body’s way to eliminate toxins in these fluids, stopping these reactions is idiotic, and not having them may be a lack of immune reaction.
That said if your body can beat the bug in a few hours then you may not get this reaction but I know no one who doesn't get slightly ill or some fever for even a few hours before kicking the bug.
In short everyone must evaluate this for themselves, but if you carry a large parasite load I would bet on the lowered immune response...