Image for Norwalk Virus article The Centers for Disease Control (CDC) and the International Council for Cruise Lines (ICCL) have been working together since the early 1970s to ensure your cruising experience is a safe, healthy, and enjoyable one.

So, why are there seemingly sudden outbreaks occurring? Sources in the cruising industry blame it on the increased popularity of cruising. More people, more ships, more destinations, and less vessel “downtime” between trips can set the stage for a Norwalk virus outbreak. But that doesn’t mean your ship needs to sail without you. Here are some tips for a safe and healthful cruising adventure.

What Is the Norwalk Virus?

The Norwalk virus is actually quite common and is not a deadly or life-threatening illness. In fact, it is second only to the common cold as a reported cause of illness in the US. The original Norwalk virus strain was named after an outbreak of gastroenteritis in a school in Norwalk, Ohio in 1968. The gastroenteritis caused by the Norwalk virus (or Norwalk-like viruses/noroviruses) is a mild, self-limiting, but highly contagious disease characterized by nausea, vomiting, diarrhea, and abdominal pain. Headache and low-grade fever may also occur. Symptoms of Norwalk virus typically develop within 1-2 days of exposure and may last from one day to one week.

Water is the most common source of outbreaks of the Norwalk virus. This may include water from municipal supplies, wells, recreational lakes, swimming pools, and water stored aboard cruise ships. The Norwalk virus is transmitted by the oral-fecal route, directly from person-to-person, through ingestion of contaminated water and foods, or through contact with a surface that has been contaminated.

Shellfish and salad ingredients are the foods most often implicated in Norwalk virus outbreaks. Ingestion of raw or insufficiently steamed clams and oysters poses a high risk of infection with Norwalk virus. Foods other than shellfish can be contaminated when washed in water that contains the virus or by food handlers carrying the virus.

What Is the Connection to Cruises?

The close living quarters of a cruise ship amplify the opportunities for transmission of Norwalk-like viruses. Because cruise ships offer such a conducive environment, the ICCL and the CDC established the Vessel Sanitation Program (VSP) in the early 1970s. This program states that every vessel with a foreign itinerary, carries 13 passengers or more, and calls in a US port is subject to unannounced, bi-annual inspections by VSP staff.

Unfortunately, despite routine cleaning and strict sanitation standards, the arrival of new, susceptible, or affected passengers every 1-2 weeks provides an environment in which the Norwalk virus can flourish.

How Can You Reduce Your Risk?

There are some measures you can take to reduce your risk of getting sick during your cruise.

Before the Trip

  • Check the history of the cruise ship you are planning to take (for example, any previous outbreaks or failed inspections).
  • If you have a chronic illness, ask your doctor if it is safe for you to go.

Once Onboard

  • Wash your hands thoroughly and often with soap and warm water, particularly before eating, preparing food, and after using the bathroom.
  • Avoid eating raw or steamed shellfish. (The Norwalk virus is strongly associated with the consumption of raw or under-steamed oysters and clams.)
  • Wash fresh fruits and vegetables before eating them.
  • Avoid other passengers who are ill.
  • Use only bottled water, even for brushing your teeth.
  • Avoid ice. (The Norwalk virus can survive freezing; many outbreaks have been traced to ice made with contaminated water.)
  • Avoid foods that may have been washed in contaminated water.
  • Go to the infirmary if you have symptoms of the virus.

What Should You Do If You Get Sick?

Seek medical attention immediately. All cases of suspected Norwalk virus should be reported to the ship’s medical staff.

The most common complication of Norwalk is dehydration. Drink plenty of bottled water, clear liquids such as defizzed ginger ale or decaffeinated colas (caffeine may make the diarrhea worse), fruit juices, or decaffeinated teas or broth made from safe drinking water.

If you become extremely sick and dehydrated, you may need a special rehydration solution. This is best obtained from the ship’s medical staff, but it may be available in a dry mix, which can be purchased in a drug store before you leave home. (Ask your doctor about this before you go). Very severe cases may require a hospital admission so that you can receive hydration and electrolytes through an IV.

Get as much rest as you can and stay calm. Gastroenteritis is an uncomfortable, but not serious illness, which will usually resolve itself within a few days. If you become ill onboard, you may be isolated from the rest of the passengers, or you may be asked to disembark at the next port. This is done for your own protection, as well as the protection of the other passengers on the ship. It may not be the end to your vacation that you had envisioned, but it will be in everyone's best interest. Remember, new ships sail every day. Once you’re feeling better, you can be on the next one!