(CNN) -- A new outbreak of a gastrointestinal illness aboard a cruise ship may have been caused by the norovirus, the ship's operator said Wednesday.
At least 66 passengers and 17 crew members came down with a quickly spreading digestive bug aboard the Crown Princess, said spokeswoman Karen Candy of Princess Cruises.
They have been isolated in their quarters, and the ship has implemented sanitation procedures developed in coordination with the Centers for Disease Control and Prevention to slow the disease's spread.
The Crown Princess, which has room for more than 3,000 passengers, left Los Angeles on Saturday for a seven-day Pacific cruise.
Though Princess Cruises believes norovirus is at the root of the outbreak, due to the quick increase in the cases of gastric ailment, Candy did not confirm it as the cause.
Norovirus is known for being readily contagious. It causes nausea, vomiting and diarrhea, and is believed to have infected passengers on a number of cruise ships in recent months.
In February, 114 passengers and 10 crew members took ill on the Holland America cruise ship ms Veendam during a week long voyage.
In January, more than 600 people on cruise ships sailing in the Caribbean fell ill from the virus, the CDC reported.
Norovirus infects many people on land, but health officials track it on cruise ships, leading to more frequent reporting of cases, the CDC said.
It is passed in person-to-person contact and can spread more easily in closed quarters.
CNN's Greg Morrison contributed to this report.