Some travelers hesitant to cruise due to gastrointestinal illness outbreak aboard ship . The CDC says the number of cases is expected to rise as more people are tested and treated for Ebola. In 2013 , about 1,200 passengers were sickened 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 outbreak aboard ship . Cause of the outbreak has not been pinpointed yet by the CDC . In 2013 , about 1,200 passengers were sickened by norovirus on cruise ships . Each year , norovirus affects an estimated 21 million people in the United States .