An unnamed Flesh-Eating Virus acts as the primary threat of the horror Cabin Fever, with the Locals acting as the secondary antagonsits due to their extreme actions to try and contain it : the virus is based on a real-life bacteria that can cause similar effects but the virus in the movie is far more deadly and fast-paced in its infection.
The earliest symptoms of the disease may be sensations of nausea, drowsiness or both. However, many known victims of the disease didn't report either of these symptoms, so their occurance seems to vary from case to case. When they do occur, they may do so as early as a few hours after initial infection.
The earliest distinct symptom of the disease will be one or more rash-like areas of tender red skin. These can appear anywhere on the body. The initial rash can take anywhere between 8 to 18 hours to develop after initial infection.Within roughly an hour, the effected skin will begin to peel, exposing the underlying dead flesh as dark scabby pits as the "rash" rapidly expands. As this process continues, the wounds open deeper and severe bleeding ensues. By this stage the flesh below and around the effected area is already dead and partially decayed. It's bond with the surrounding flesh and bone is so weak that large tracts of flesh have been known to peel away with as little pressure as a person uses when shaving with a razor.
During this process, other areas of skin on the body become symptomatic and begin to degrade as well. It is possible for the process to go faster in some areas of the body then others. Evidence suggests the process can be accelerated by physical trauma, such as firmly squeezing previously uneffected flesh.
Later symptoms of the disease include difficulty breathing and projectile vomiting of blood. Some victims have been know to merely cough up small volumes of blood before their other symptoms become particularly severe.
Within 24 hours of initial exposure the victim will usually be practically immobile due to tissue degradation and massive blood loss. They may also lapse in and out of consciousness.
The virus is a multi-species disease, known to infect pigs and dogs (at the very least) as well as humans.
It is a blood-born disease that can be contracted by having infected blood exposed to one's own bloodstream via a wound, ingestion or through an orifice like the eyes. The virus can also be passed into a water supply and subsequently to anyone who is exposed to the water in a similar manner.
The disease can also be transmitted sexually. It is unknown whether kissing alone can spread the disease, although it is highly probable that it can.
Events Leading to Outbreak
At some point a dog is infected with a volatile flesh-eating virus and dies, sometime later its owner (a hermit) tries to wake the dog up and finds himself exposed to the infected blood as a result : this causes the hermit to stagger into the woods where he becomes heavily infected.
It is later revealed that somehow the livestock at a local pig farm had also become infected around this time.
The hermit comes upon a small cabin being occupied by 5 vacationing college students, Karen, Paul, Bert, Marcy and Jeff. By this point he is severely ill and covered in gruesome, bleeding sores. While the students argue about how to help the sick man without exposing themselves to his sickness, the hermit attempts to steal their car. The students scare the hermit out of the car before he can drive off and while trying to defend themselves with a burning stick, accidentally set the man on fire.
The students survive the altercation without contracting the disease, but unfortunately in an effort to extinguish himself the burning hermit ran into the nearby reservoir where he subsequently died of his injuries. The drinking water of the cabin, unbeknownst to the students, thus became infected. Karen was the first to become sick through drinking tainted water and developed her first bloody sore about 8 hours after infection.
Marcy was the second to be infected when she injested the water in a cup of tea, but she was actually the third to exhibit symptoms. She later had unprotected sex with Paul through which she passed the disease to him. It was actually during this sexual encounter that Marcy's first symptom, painful rashes on her back, developed, though neither of the lovers noticed it at the time. Shortly afterward, the rashes degraded into bloody sores like Karen's and the flesh of Marcy's calves degraded and peeled away.
Bert was the third to drink the tainted water and began coughing up blood the following morning. He also discovered a previously unnoticed bloody sore on his belly. He managed to flee to a general store some distance away, where he was bitten by a mentally handicapped young boy named Dennis who thus became infected via exposure to Bert's blood. The boy was eventually taken to intensive care at the local hospital. The boy's fate was ultimately unknown, though it's unlikely he survived.
Paul wandered the countryside well into the night, by which time he'd begun to develop the telltale sores of the disease.
Though 4 out of the 5 students were infected with the disease and ultimately died, none of their deaths were a direct result of the disease.
Paul is eventually taken to a hospital but the doctors are unable to treat such a volatile disease, the sheriff decides to "deal with" the situation and instructs Deputy Winston to get rid him.
Winston agrees but instead of properly disposing of Paul and ensuring the infection can not spread he decides to dump Paul in a creek - next to water, which causes the infected blood to spread into said water.
Due to this the town's water supply is infected and local children make lemonade from it, which is given to the police who had initiated the "purge" : worse still the water is sent en mass across the country by truck as bottled water, suggesting a much worse outbreak in the future (possibly on an epidemic scale).