During the week long summer camp one of the best things to do is either make sure the medic knows about the scouts disability or let their counselors director know. If the counselor is an adult, you may be able to let them know directly, but the director is the best bet. Most summer camp staff (I know we were, and I've heard of others) take an instruction on dealing with scouts with disabilities, this helps out a lot. As a staff member, knowing why the scout runs off by himself and doesn't want to participate is a big big help. The directors will let their staff know on an as needed basis, this way it doesn't get out to the whole camp what the scouts disability is.
One good idea is to try and keep them busy, don't let the scouts mind wander. If need be ask him to do simple tasks for you, or ask him to be the PL over the week. This will give him something to occupy his time with. Granted, this does not always work, but it has worked in the past.