In Cabin Fever, What Kind of Virus do the peers (friends) come across around the Cabin and woods?

All the employees were held at gunpoint, and then after they had been gagged and beaten, they were tied to chairs. They were set in a circle, so that way, everybody was forced to watch everybody else. And then the robber, this sick maniac, he goes and finds one of those little ball-pen hammers, and then one by one, he smashed the backs of their heads open with the hammer. Everyone had to watch their friends die, knowing that they'd soon be next. The guy doesn't stop there. He goes and he breaks out the fire axe. The alarm goes off; he doesn't give a shit. He hacked off all their limbs.

**The above was a story told around a fire in what Eli Roth film?**