[Maribelle who had been watching this conversation, feels rather guilty for asking a greedy question about treasure when the noble thing to do would have been to ask how to help stop the plague. So she takes a moment to help explain this to Sakura since she's been here before.]

Allow me to explain... the poltergeist who brought us here, Davy Jones? Have you noticed how he's capable of dragging people here from other worlds, and other times? Death doesn't mean much to a being such as that, and because of that he can bring anyone back who has died. He brought us here in the first place, so he doesn't want anyone leaving even if that method is... death. So it's likely that he snatches up people from their time line right before they would die, and pulls them back into his domain.

Either that or he's found a way to defy death altogether, and simply resurrect those who have died. I'll tell you this much though, don't think of yourself as immortal, because I don't think Davy Jones particularly likes the idea of constantly bringing someone back from the brink of death.