Verdict:

Serial killer movies have become boring over the years, because they all follow the same format: a group of actors playing teenagers gets killed one by one. Cabin Fever is the first movie I’ve encountered, where the serial killer is a disease.
This is an interesting take, and it makes a number of cliché’s impossible. It’s harder to have a jump-scare with an axe-wielding monster, when there is no axe-wielding monster. The fact that the movie still succeeds in creating jump scares is honestly impressive.
The group of teenagers brought in for the slaughter is a group of not unlikable city college students coming over to a strange small local community. They behave erratically and panic when under pressure. This unlikability and reactionary behaviour makes them appear rather realistic, even though the specific actions of those characters are not. And it is far more fun to see them get killed off as a result.
The creepy horror is garnished with bizarre humour. That humour doesn’t always work, but it’s funny just because of how odd some of the scenes are.
The practical effects look sufficiently gross. The isolated cabin in the woods really works as a setting for a killer fever. Considering the small budget this film had, the horror is surprisingly effective.
There is not that much happening in the movie, and it could have done much more with its original idea than it did, but the movie was creepy – something a lot of horror movies fail to do.
I think the people missed the point of this film. The characters are unlikable, but they are supposed to be unlikable. Some scenes are bizarre, but those scenes are designed for the sake of absurdist humour. The main concept is creative and is actually scary.