A cruise ship headed from Canada to Boston has reported a norovirus outbreak that sickened 75 people on board.

The Oceania Insignia, operated by Oceania Cruises, departed from Montreal on Oct. 16, according to CruiseMapper.com. It is making several stops in Canada before docking in Portland, Maine on Oct. 26 and then Boston on Oct. 27.

The Centers for Disease Control says that the outbreak was first reported on Monday. Seventy-four out of 637 passengers (11.6%) reported feeling sick, as did one crew member. 

"At Oceania Cruises, the health and safety of our guests is the number one priority," a spokesperson for Oceania Cruises said in a statement. "A number of guests on the current voyage of the Oceania Insignia have reported symptoms of acute gastroenteritis. The ship's Sanitation Officer has activated the CDC approved protocol and all guests experiencing symptoms are being treated."

The predominant symptoms being reported are diarrhea and vomiting. The crew has stepped up cleaning and disinfection of the ship.  Sick passengers have been asked to isolate in their rooms.

The CDC said it is remotely monitoring the situation, and is reviewing the ship's outbreak response and sanitation procedures.

Norovirus is "very contagious" and the leading cause of vomiting and diarrhea in the United States, according to the CDC. In September, nearly 100 people became sick with norovirus on a Royal Caribbean cruise from San Diego to Miami. 

Symptoms generally last between one and three days, but people can still spread the virus for days afterward. The best way to protect against norovirus is to wash your hands thoroughly and often.