Norovirus Outbreak on Fred. Olsen Ship

An outbreak of the norovirus stomach bug has sickened 160 people on board a Fred. Olsen Cruise Lines ship.

The norovirus outbreak took place on board the Britain-based line's Balmoral during a transatlantic cruise, the U.S. Centers for Disease Control and Prevention (CDC) said in a statement.

The CDC said 153 passengers and six crew members had fallen ill from norovirus, whose symptoms include vomiting and diarrhea.

Fred. Olsen said in a statement that the vessel had docked at Norfolk in the U.S. and seven passengers were in isolation. Most of the passengers were from Britain, it said. The line also stated that the Balmoral has not been quarantined in Norfolk as some reports indicate. 

The CDC said that the cruise line and the ship's crew had increased cleaning and disinfection and collected stool specimens. The company also sent a corporate sanitation manager to oversee handling of the outbreak. Fred. Olsen exceeds the requirements of the CDC, in that it isolates its guests in their rooms for 48 hours, instead of the 24 hours required by the CDC.

CDC health officers and an epidemiologist plan to board the Balmoral when it arrives in Baltimore this weekend, the CDC said.

Norovirus is the most common cause of U.S. food-borne disease outbreaks. Infections usually occur in places such as hospitals, cruise ships and universities, where people eat and live in close quarters.

About 19 million to 21 million norovirus cases, with 570 to 800 related deaths, are reported in the United States each year, according to the CDC.

The CDC has investigated the following cruise ship outbreaks this year: