Do not let your Scouts substitute sodas for water when they are trying to rehydrate. Blisters on the feet - the long days hiking around the site and the hot, humid conditions require thoughtful attention to footwear. Wear sturdy shoes or hiking boots, and use the double layer sock system, just like on a regular backpack trip. While traveling to and from the Jamboree, your health resources are less apparent, particularly because you are in strange towns and cities. As a family physician with ten years experience as a scoutmaster through annual camps, Philmont, Summers canoe base, and as a subcamp physician at NJ93, let me tell you that it is always the kid that's allergic that finds the bee.
Local reaction involves irritation, redness, and swelling at the site of the sting.
This can be treated with ice and observation. Regional reaction involves swelling past the site of the sting and spreading in the general region, such as the arm, etc. This can be treated with ice and 25-50 mg of benadryl which can be obtained over the counter. A systemic reaction involves swelling, shock, and respiratory distress. In the case of a systemic reaction, I would call 911 and then administer adrenaline asap as well as benadryl, if available.