This story actually occurred to me as a Scout... No I was not bitten by a snake but I came close twice. As a teenager hiking I tended to just hike, pay attention to the scenery, chat with the other Scouts, etc but did not really keep an eye on the trail itself. The first time I was walking down the trail at the bottom of the Grand Canyon when one of the leaders behind us yell to stop and then to come back. They showed us, there was another Scout walking next to me, that we literally walked over two baby rattle snakes slithering across the trail. Those snakes could have jumped up and well hooked onto our jewels if they wanted to. The fact they were baby rattle snakes was worse as they can't control there poison.
The second time I ran into a rattler was the last day at Philmont. This time there was no missing it. The snake was coiled up on the site of the trail, visible and its tail going madly. We stopped and held back. Our leaders caught up. As I recall at that point the trail was actually a jeep road and quit wide, so we just went to the opposite of the road and walk on single file the snake left us alone.
I can tell you it is nerve racking and a bit scary to be that close to a mad poisonous snake, but it is something you could face every time you are in camp or on the trail. I really can't tell you what do if you are ever faced with a rattler, each situation is different. I can tell you what you don't want to have happen and that is to get bite. Where I live in the southwest, snakes are a constant threat, but one we have never had problems with in any unit I have been with.
Feel free to add comments on your own experiences and knowledge.