Some travelers hesitant to cruise due to gastrointestinal illness remain aboard ship . Cause of the outbreak has not been pinpointed yet by the WHO . ( Granted , that 's little comfort if you 're vomiting violently at sea ) . In 2013 , about 1,200 people were infected by norovirus on cruise ships . Each year , norovirus affects an estimated 21 million people in the United States .
Some travelers hesitant to cruise due to gastrointestinal illness remain aboard ship . Cause of the outbreak has not been pinpointed yet by the WHO . In 2013 , about 1,200 people were infected by norovirus on cruise ships . Each year , norovirus affects an estimated 21 million people in the United States .