Originally published in The Ottawa Citizen December 3, 2002
Original Title: Cruise Ship: The perils of adult daycare

Recent reports of three cruise ship outbreaks of viral diarrheal illness (gastroenteritis) bring into focus how easily infections spread. Each ship had hundreds of passengers who fell ill. Carnival’s cruise ship Fascination, Disney’s Magic and Holland America’s Amsterdam all underwent extensive decontamination procedures.

Florida’s Department of Health and Atlanta’s Centers for Disease Control (CDC) both think that Norwalk virus is the culprit. Food borne disease is a significant cause of gastroenteritis. The CDC tabulated approximately 76 million diarrheal illnesses, 325,000 hospitalizations, and 5000 deaths each year in the United States based upon surveillance data from multiple sources.

Norwalk virus is the one of the most common causes of gastroenteritis in children and adults. The virus grows within the gastrointestinal tract. It is spread by fecal-oral route. As the term implies, ineffective hand washing after a bowel movement leaves viral residue on the hands. This residue spreads by contact. When another person touches the residue-laden object or hand and brings their hand to their mouth, voila, the porcelain throne becomes an important piece of furniture.

Indeed, passengers disembarking at Caribbean and Central American ports are exposed to the local food and water supply. Although most travelers are aware of the risks it is difficult to ensure complete protection from illness. With thousands of passengers on cruise ships, the potential for viral propagation through this ‘captive’ population is great.

The dense passenger population on cruise ships is akin to the children’s daycare scenario. The Norwalk virus causes most school and daycare-based cases of gastroenteritis. Soiling of clothes, lack of handwashing and close physical contact between children with less than perfect hygiene habits are fertile breeding grounds for this disease.

Cruise ships are adult playgrounds with unlimited buffets and drinks, numerous contact sports and activities, close contact between people, and ports of call to towns and cities with potential sources of food and water contamination. These factors contribute to an increase in overall risk of infection. Indeed, it only requires one infected person among the passengers to contaminate all these open and available sources.

According to Holland America, the decontamination process involves everything passengers and crew touch. All items touched by people need to be cleansed. A spokesperson for Holland America stated “The cleaning crew had to steam clean 300,000 square feet of carpet, replace 4,000 pillows and hand scrub every dish, eating utensil, glass and poker chip. Places where passengers put their hands, such as door handles, chair armrests, railings and tabletops also were scrubbed with a strong chlorine solution for several minutes, the only way to kill the virus. Even the ship directory in every cabin was replaced.”

Despite this due diligence, the Norwalk virus continues to be a problem. The recent closure of several Eastern Ontario hospitals attests to the difficulties controlling and limiting the spread of this virus.

The Norwalk virus can cause either a mild fever with watery diarrhea or a more severe fever with vomiting, headache, muscle ache and fatigue. Once infected, the virus will incubate about 24 to 48 hours before the symptoms begin. Stomach cramps and nausea are the first to appear starting gradually or hit full force. Vomiting follows thereafter. A low-grade fever of 38.3 to 38.9ºC (101 to 102ºF) occurs in approximately one-half of cases. The infection lasts about 48 to 72 hours. Infected persons typically have non-bloody, watery diarrhea with four to eight bowel movements over a 24 hour period. There is usually no mucous seen in the stools because the walls of the small intestine do not become inflamed. Recovery is usually rapid. Children in particular are at risk for dehydration.

The Norwalk virus is shed in the stools. This shedding occurs over the first 24 to 48 hours after the illness. It is rarely detected beyond 72 hours after the onset of vomiting or diarrhea.

If you are planning a cruise vacation or any vacation for that matter, there may be some instances and locales where hand washing facilities may be substandard or unavailable.

Judicious use of a particular product can reduce your risk of gastroenteritis and other infections in combination with the usual travel precautions. Purell(r) is an alcohol gel disinfectant available in a pump or small squeeze tube format. The gel’s alcohol concentration is great enough to kill most viruses and bacteria. It does not require water to rinse or wash the hands. The gel dries in about ten to 20 seconds after its application. It can be used as many times as is necessary. Carry it with you at all times.

As thorough as the ship decontamination efforts seem to be, will they reduce future ship-wide viral outbreaks? Although the cruise lines have done their best to reduce the risk, it is impossible to screen each passenger for disease. Further not all people are equally effective with hygiene procedures.

Ultimately, the onus is on travelers to do their best to reduce their risk of travel-related illnesses.

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© Dr. Barry Dworkin 2002