A friend of mine got it once but we figured that she got it from the water that she was swimming in in a lake.  As for myself I have never picked it up, even after drinking from a lot of springs in the hills.  One year deer hunting I was bent over double and fertilized every bush of the hill side one day but it wasn't from drinking the water. 

I picked it up once when I was 12 from a place I would not have even worried about it. It was a spring coming right out of a rock wall in the bottom of a canyon. On the other hand I have actually drank from places that should have killed me and have not gotten sick (not recommended).

My brother and his family a couple of years ago all got it. The only thing they can figure is they were keeping there water bottles cool in the creek and got it from that.

Quinton 

I don't drink out of streams unless I can see the source and know there's not something peeing in it or dead upstream.  I'm a big believer in filters.  I've got an MSR filter I take into the back country if I'm on an extended trip.  That thing kept a buddy and I in water for a week and a half at a time on trips, and the water we were using came from a river full of dead and dying salmon.  I'd rather spend time pumping my filter than pumping my guts.

I've heard it's pretty nasty stuff.  Was talking to a lady a while ago who got it and had problems and was on treatment for a long time.  Doesn't sound like fun to me.  There has to be some way of becoming immune.  Afterall early man's only source for water was from springs and creeks.  They didn't have water treatment back then and they surey drank from these.  I'd only drink from a spring or creek if I was severley dehydrated and needed water badly.  Otherwise I always carry water purification capabilities with me when I'm in the bush.

Got it once about 20 years ago. I believe it was from our town's tapwater, because the local doc's office had several cases of giardia that spring. We now filter our tapwater. 

I remember being pretty sick for most of the summer and it seemed like a long time until I felt well again. Really don't ever want to do that again. 

I never drink water right from a stream, no matter how clean it looks. 

The problems with drinking right out of the spring is that the microbes that cause the problems are so small you will never see them no matter how clear the spring or water is.  One thing is that when I was in high school I came home from hunting and had a canteen full of spring water that I always drank and since I was taking a chemistry class I decided to do a paper on natural spring water vrs tap water.  After I got done doing my little study I found out that the spring water that I had was purer than the tap water from the school.  But you stll will take a lot of chances drinking unfiltered water out in the sticks. 

I remember reading a article about our immune systems and in it they were discussing weather we are better off now than we were a 100 years ago, now this was over 10 years ago.  The consensus was that we are healthier now but a lot of the natural antibodies that we use to have that protected us from a lot of the problems years ago are now gone out of our bodies.  But then a 100 years ago if you lived to be 60 years old you were way old. 

It's not worth the pain & misery to think that the water is clean & free from giardia.  If a warm blooded animal can defecate in the water, regardless of where in the world your at, you can assume one has.  The protozoan responsible for the illness typically isn't very numerous but it litterally only takes one to completely mess up you day (not to mention your sleeping bag).  The first 5 gallons you drank could have been free of the bug but that last half pint might have had one or two.  Game Over.

Chemical disinfectants won't help much if any.  Best to stick to fine micron filter systems instead.  Besides, chemical treatments taste like ... uh... well they taste bad.

I don't know for sure.  As a farm kid we all routinely would drink our fill from streams running through the pastures on a hot summer day.  Maybe I've been lucky.  ::confused2  I've never been diagnoses with it, but I've been sick from unknown sources from time to time.  There is usually some sort of "stomach bug" going around town.  If not, I chalk it up to uncooked food or some such.  I have never blamed the water.  Of course - I grew up drinking water from a pipe that ran from a spring on the hill to the house.  I've seen frogs and fish in that spring and I still drink from it regularly when I drink tap water at my parents' house.  It does not seem to be an issue.  I don't see it as any different as drinking water from my own well.  Who knows what happened uphill where that water ran off before soaking into the ground and coming to my well point? 

Outfitter I worked for near the Bob in MT got it, I knew i never wanted to get it after seeing him get it I was sure

Actuall the Bob is where I picked it up myself. And I never want to have it again.