Here's what I would have done with the concept: All THREE girls would have been bitten by the same unknown creature. On the way back to civilization, they discover that Casey accidentally killed the man who attempted to rape her. Unfortunately, he was also the son of an influential local tycoon.
Fearful their story wouldn't be believed, while also getting increasingly sick from the mutations occurring inside their bodies, Casey and her friends hole up inside an abandoned house or shack to try and come up with a plan to sneak out of the country. The rest of the film would be an intimate character piece as each girl grapples with the crisis thrust upon her in a different way, as they slowly come to the tragic realization they'll never be going home.
I can't guarantee it would be a better version of the movie, but at least we'd get three mutating women instead of just one.
