It's a Personal Thing
I have always tried to make sure that when I go on group holidays
then the ground rules are established. Especially when diving in exotic
locations. Like the Hurricane said "It's my work and I do it for pay" and
they can't afford my rates to call me back from leave. I also make it
clear that I shall not be in any way abstinent during my holiday and
anybody seeking my advice, like in any other social gambit, will have to
take me as they find me.
And you cannot be said to have any "duty of care", except in life-
threatening emergency, to clients of another business who have volunteered
to put themselves through risks which one hopes they have sought to
calculate and suitably insure.
Having said that you do have a duty of self-protection both as to
your professional reputation and your relationships with your fellows.
You can't walk away but it may be acceptable to call somebody
stupid/clumsy (personal experience, giving and receiving).
So to the scenarios:
1) Designate a single toilet, well-marked, for use by the victims.
This will prevent spread of infection. Emphasise hand washing. Periodic
inspection for rose spots or signs of peritonism may reassure you. And
rehydration. If you've been on the boat for a few days when people get
ill then complain bitterly to the charter company and write to "Dive".
2) This wound will be contaminated both by foreign bodies (sand and
broken coral) and by coral toxins. It should not be treated by primary
closure but cleaned and rested, with elevation and antibiotics, until it
heals by secondary intention or facilities are available for debridement.
3) Passenger A is the author of his/her own downfall and bears the
consequences of their own actions. It is their decision, not yours,
whether to curtail the expedition and the fact that you have not been able
to medicate them means that they take this decision with a clear head. If
they're insured then that's their losses taken care of. Passengers B-Q
should check their own policies and prepare claims.
Competing interests: No competing interests