> That would depend on where the finger was before it was inserted into the
> nostril, I should think. ;0)
Amusing, but not obvious.
What gets transferred to a human is a giardia cyst. This is analogous to a small round egg. It has to reach the intestines, via the stomach, before the cyst can hatch into an active bug.
Exactly how a 20 micron cyst gets from the nose to the stomach and beyond is not obvious at all. Even if it was ... snorted?, it would end up in the lungs, not the stomach. From there it would be exhaled.
There is also the question of how often you pick your nose while walking, as opposed to drinking contaminated water or eating food with contaminated hands.
I want to see validated medical research before I believe. (This statement should be read exactly as it stands. Extrapolations are not valid.)