According to a press release the two films, Cabin Fever: Patient Zero and Cabin Fever: Outbreak will shoot back to back in the Dominican Republic in early Spring of 2012
Jake Wade Wall (The Hitcher, When Strangers Call) has signed on to pen the screenplay for Cabin Fever: Patient Zero. When a cruise ship in the Caribbean collides with an abandoned research vessel, a deadly virus is unleashed. Passengers must find a way to survive before the flesh eating disease consumes them all.
Cabin Fever: Outbereak is being written by Adam and Deborah Marcus (Leatherface 3D, I Walked With a Zombie). In this film a doctor and his family travel to a remote Caribbean island to investigate a minor flu outbreak, only to discover a vicious flesh-eating virus that threatens everyone on the island. The family is faced with responsibility to prevent a worldwide epidemic.
Eli Roth, the writer/director who created the franchise while working as a PA on the Howard Stern comedy Private Parts, apparently has nothing to do with the new films. But then again, it sounds like that outside of the fleshing eating virus these sequels have no much to do with the the original film anyway.