When I through-hiked the PCT a number of people I was hiking with came down with giardia. We drank from the same sources for weeks. They treated their water and I never did and I still never got sick. Why?
Submitted by - Jerrad, Grass Valley, CA
Some people are immune to Giardia, and that could be the reason. Or, since it takes several of the protozoa to cause disease, he might have simply been lucky and never ingested enough to make him sick.