The movie starts like so many others: some best friends load up on beer for a weekend of bonding and debauchery. Two of the characters even make a pact to drink only alcohol all weekend. Instead of hedonism destroying the students, though, it theoretically saves the day: the sickness is acquired from drinking the infected tap water. That means that the only way to stay safe is to be wildly drunk (or drink non-alcholic beverages from outside of the cabin, but clearly, those don't exist in this version of reality).
Eli Roth is most effective as a director when studying the physical effects of the illness. The smallest everyday things like touching someone on the back or shaving legs becomes amplified to skin-shedding, blood-drenched horror. But it's not enough to leave brutality to a mere physical level; it clearly has to be translated to a sexual level. Lead character Paul (Rider Strong) finally decides to act on his crush on Karen (Jordan Ladd). As he sensually caresses her, he pulls his hand out of her underwear to discover that a large portion of her skin has sloughed off in the process. In a way, this expresses the masculine fear of menstruation, but it also begins the quick physical deterioration of the characters. What's most terrifying is that the group has seemingly no means of escape, and without any clean drinking water available, all seem doomed to meet the same fate.
The film also plays up the campy elements of a woods movie. Roth himself has a cameo as Grimm, a party camper who stumbles upon the cabin. He gets the pleasure of delivering the most hilarious movie of the film; after being asked if his dog, Dr. Mambo, was a professor, he replied, "Yeah, he's a professor...OF BEING A DOG! FACE!" Roth also plays upon backwoods stereotypes, showcasing a farmer arm-deep in hog, a karate-chopping kid who's obsessed with pancakes, and a elderly shop owner who's seemingly incredibly racist.
Cabin Fever is effective because it combines the isolation of a cabin-in-the-woods film with the hysteria of an infection movie. No one is able to think clearly or research the situation thoroughly with modern technology, so panic is an inevitability. Unlike in his other movies, Roth is able to strike the perfect balance of blood, humor, and suspense.