It is also impossible for governmental entities such as the Centers for Disease Control and Prevention to conduct a thorough, painstaking epidemiology study to ascertain the type of virus and its origin. Cruise lines quickly blame the passengers for not washing their hands, but the CDC and the Food and Drug Administration concluded long ago that the most likely and common source of norovirus is contaminated food or water.

Crew members say that infected workers often do not complain of their illness out of fear of not being paid or of losing their jobs. Cruise lines tell the passengers to use hand sanitizers, but the culprit may be norovirus-laden salad.

Unlike the U.S. commercial aviation industry, with strict Federal Aviation Administration oversight that can ground a fleet of aircraft, the cruise industry is largely accountable to countries like Panama or the Bahamas -- which may or may not want to offend their cruise line friends in Miami.

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