Am I more susceptible to giardiasis when camping?

Depends on exposure. Animal contamination of lakes and ponds may make camping a riskier event than sitting at home. Access to purified water and proper boiling of your utensils can lower your risk if you use lake or well water for cleaning. Boiling your water for 10 minutes will illiminate the threat if you are unsure of the water.
Yes. If you drink water from a contaminated water source.