The Coase theorem would seem to come into play here. We should be able to pay West African nations enough to compensate them for any harm of a travel ban.
I'm not sure this would fully solve the problem Christian mentions in the second half of his comment. The problem is that trust is priceless, which may impose very high transaction costs.
Related to: Forty Days , Low Hanging Poop
From professor Gregory Cochran's blog West Hunters.