** FILE ** This undated Negative-stain Transmission Electron Microscopy image, provided by the U.S. Environmental Protection Agency EPA, shows a Norovirus, also known as the Norwalk Virus. Norovirus is a genus of viruses of the family Caliciviridae. Recent scientific findings reveal that the genus causes around 50 percent of all gastroenteritis around the world. (AP Photo/F.P. Williams, U.S. EPA)
February 9, 2012 5:00:03 PM PST
PHILADELPHIA, PA.; February 9, 2012 --
Norovirus is often called the "cruise ship virus," because it is seen a lot on cruise ships.he virus spreads like wildfire in close quarters, such as ships, schools, or college dorms.