Can you "catch" Giardia from your dog? I understand humans can get Giardia as well, but I'm having a tough time understanding how? Is it from drinking water (say from a stream) or can you actually catch it from your dog? And if you can catch it from your dog - how? Would you literally have to have direct contact with stool or what???
Yes, you can "catch" it from your dog. The Giardia microorganisms are very hardy and can persist for a long time. So even though it's most commonly transmitted through contact with excrement or in water, it can also be picked up from surfaces that have come in contact with infected material (if they were not disinfected and even if they appear clean).
So just a scratch on the ear or regular petting won't pose much risk, but think butt-scoot, or grooming-then-slobbery-kisses and you get a more likely pathway. It doesn't mean don't touch your dog if he/she has Giardia. But it does mean be super vigilent about disinfecting surfaces and washing your hands after contact.
Giardia is horrible and from working in childcare for nearly 20 years before I changed careers, it was one that plagued us. Back then for humans, it wasn't picked up in normal lab tests and a specific Giardia test had to be requested which often delayed diagnosis. I don't know if that has changed (hope so).