Giardia

My sister and I went fishing on Chatooga River. She was young and new to fly fishing, and I should have known better. We had no food or water with us. About 2:00 pm we were pretty dehydrated, and she told me that she was going to get a drink from a spring pool that flowed out of a pocket along one of the banks. The following conversation is true and verbatim:

me: Don't drink from that. You will get Giardia. We need to drive back for water.
her: What is giardia?
me: A ciliate common in streams. You ingest it, and about two weeks from now you have massive diarrhea. It will be so severe and debilitating that you will lose 20 pounds. The medication that treats Giardia causes nausea and will exacerbate your weight loss because you won't be able to eat.
Her: So you are telling me that this is likely to happen if I drink that water?
me: Yes.
Her: But this Giardia, it is completely curable, right? You do get better and there are no long term effects. You just lose about 20 pounds and maybe more due to the nausea.
me: Yes.
Her: You are sure about this.
me: Yes.

She threw her fly rod to the side and dove in. I nearly fell over laughing. We both drank. Neither of us got Giardia. We now take food and water. We still laugh about it.

The little spring was then christened "Giardia springs". Fast forward 10 years.
me: I'm going downstream. I want to fish the giant pool.
Her: I want to fish up from the bridge. Meet me at Giardia springs at noon for lunch.
Me: OK, see you there at noon.