The Norovirus Versus Cruise Ships

The outbreak of norovirus that sickened nearly 700 people—630 passengers and 54 crew members—on Royal Caribbean’s Explorer of the Seas cruise ship in January was caused by a newer strain of the virus known as the Sydney strain, the CDC reported on February 6. The strain first emerged in 2012 in Sydney, Australia.

Norovirus is the leading cause of foodborne illness, and a particularly troublesome pathogen for cruise ships; of the nine cruise ship disease outbreaks tracked by the CDC’s Vessel Sanitation Program in 2013, seven involved norovirus.

PURE Bioscience, the makers of a hard-surface antimicrobial called PURE Hard Surface—on the market for several years but only recently focused on the food industry—believes its product could help prevent such outbreaks. It uses a patented silver dihydrogen citrate (SDC) technology that is colorless, odorless, tasteless, and non-toxic.

“It kills a broad range of bacteria, viruses, and funguses,” says CEO Hank Lambert. “It also has a 24-hour residual kill: If it’s wiped onto a surface, it will continue killing pathogens that come in contact with that surface for up to 24 hours.” That could be particularly advantageous in places like cruise ship buffets, where countless hands are constantly touching tongs, trays, and countertops—and then food.

But products like this would have to actually be used in order to be effective—something that’s not guaranteed. In a study published in Clinical Infectious Diseases in 2009, scientists marked more than 8,300 objects in cruise ship restrooms, such as toilet seats, flush handles, and baby changing tables with an easily removed substance that could only be seen under UV light. Only about one-third of the objects were cleaned daily. On three ships, the baby changing tables were not cleaned even once over the three-year study period.

Like commercial cruise lines, Navy ships also have a number of people in close quarters, but unlike cruise lines, the Navy has been able to avoid massive norovirus outbreaks. According to a recent CNN article, keeping vessels extraordinarily clean is part of the daily routine for everyone onboard U.S. Navy ships. Cleaning is constant in the kitchens to prevent foodborne illnesses. Sailors swab, inspect, scrub, and scour every day.

Can Navy tactics be applied to cruise ships?

“If you have a ship whose main center of gravity is social gatherings, food places, dancing areas places for libations, and gating on decks and swimming pools—all those things that sailors wish they had, but don’t have on our Navy ships—then I think it is a much more challenging environment to control the spread of a highly contagious virus,” Vice Adm. Matthew Nathan, Surgeon General of the Navy, told CNN.



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