The study by scientists from Boston University School of Medicine, Carney Hospital, the Cambridge Health Alliance and Tufts University School of Medicine is said to be the first of environmental hygiene aboard cruise ships.
The researchers inspected 273 randomly selected public restrooms aboard various ships and found only 37 percent were cleaned daily. Although some objects in most restrooms were cleaned at least daily, the scientists found on 275 occasions no objects in a restroom were cleaned for at least 24 hours.
The least thoroughly cleaned object was baby changing tables.
The researchers said they found the thoroughness of cleaning did not differ by cruise line and did not correlate with Center for Disease Control and Prevention Vessel Sanitation Program inspection scores that averaged 97 out of a possible 100 points for the study vessels.
The research appears in the journal Clinical Infectious Diseases.