Noroviruses on Cruise Ships - Vessel Sanitation Program

Noroviruses on Cruise Ships

The cruise industry ships are among the world's safest means of transportation, safer even than air travel. Continuous safety improvement programs are implemented. The Vessel Sanitation Program (VSP) at the Centers for Disease Control and Prevention (CDC) assists the cruise ship industry to prevent and control the introduction, transmission, and spread of gastrointestinal (GI) illnesses on cruise ships.

Norovirus is a very contagious virus. You can get norovirus from an infected person, contaminated food or water, or by touching contaminated surfaces. The virus causes your stomach or intestines or both to get inflamed (acute gastroenteritis). This leads you to have stomach pain, nausea, and diarrhea and to throw up.

Anyone can be infected with norovirus and get sick. Also, you can have norovirus illness many times in your life. Norovirus illness can be serious, especially for young children and older adults.


Norovirus is the most common cause of acute gastroenteritis in the United States. Each year, it causes 19-21 million illnesses and contributes to 56,000-71,000 hospitalizations and 570-800 deaths. Norovirus is also the most common cause of foodborne-disease outbreaks in the United States.

The best way to help prevent norovirus is to practice proper hand washing and general cleanliness.


Why Noroviruses Are Associated With Cruise Ships

  • Health officials track illness on cruise ships. So outbreaks are found and reported more quickly on a cruise ship than on land.
  • Close living quarters may increase the amount of group contact.
  • People joining the ship may bring the virus to other passengers and crew.
Health officials track illness on cruise ships.

Norovirus Symptoms

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Norovirus causes inflammation of the stomach or intestines or both. This is called acute gastroenteritis.

The most common symptoms:

  • diarrhea
  • throwing up
  • nausea
  • stomach pain

Other Symptoms:

  • fever
  • headache
  • body aches

A person usually develops symptoms 12 to 48 hours after being exposed to norovirus. Most people with norovirus illness get better within 1 to 3 days.

If you have norovirus illness, you can feel extremely ill and throw up or have diarrhea many times a day. This can lead to dehydration, especially in young children, older adults, and people with other illnesses.

Symptoms of dehydration:

  • decrease in urination
  • dry mouth and throat
  • feeling dizzy when standing up

Children who are dehydrated may cry with few or no tears and be unusually sleepy or fussy.


Norovirus Transmission

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Norovirus is a highly contagious virus. Anyone can get infected with norovirus and get sick. Also, you can get norovirus illness many times in your life. One reason for this is that there are many different types of noroviruses. Being infected with one type of norovirus may not protect you against other types.

Norovirus can be found in your stool (feces) even before you start feeling sick. The virus can stay in your stool for 2 weeks or more after you feel better.

You are most contagious:

  • when you are sick with norovirus illness, and
  • during the first few days after you recover from norovirus illness.

You can become infected with norovirus by accidentally getting stool or vomit from infected people in your mouth. This usually happens by:

  • eating food or drinking liquids that are contaminated with norovirus,
  • touching surfaces or objects contaminated with norovirus then putting your fingers in your mouth, or
  • having contact with someone who is infected with norovirus (for example, caring for or sharing food or eating utensils with someone with norovirus illness).

Norovirus can spread quickly in closed places like daycare centers, nursing homes, schools, and cruise ships. Most norovirus outbreaks happen from November to April in the United States.

Norovirus And Food

Norovirus is the leading cause of illness and outbreaks from contaminated food in the United States. Most of these outbreaks occur in the food service settings like restaurants. Infected food workers are frequently the source of the outbreaks, often by touching ready-to-eat foods, such as raw fruits and vegetables, with their bare hands before serving them. However, any food served raw or handled after being cooked can get contaminated with norovirus.

Norovirus outbreaks can also occur from foods, such as oysters, fruits, and vegetables, that are contaminated at their source.


Preventing Norovirus Infection

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There is no vaccine to prevent norovirus infection, but research is being done in this area.

Practice Proper Hand Hygiene

Wash your hands carefully with soap and water:

  • especially after using the toilet and changing diapers, and
  • always before eating, preparing, or handling food.

Noroviruses can be found in your vomit or stool even before you start feeling sick. The virus can stay in your stool for 2 weeks or more after you feel better. So, it is important to continue washing your hands often during this time.

Alcohol-based hand sanitizers can be used in addition to hand washing. But, they should not be used as a substitute for washing with soap and water.

Wash Fruits And Vegetables And Cook Seafood Thoroughly

Carefully wash fruits and vegetables before preparing and eating them. Cook oysters and other shellfish thoroughly before eating them.

Be aware that noroviruses are relatively resistant. They can survive temperatures as high as 140°F and quick steaming processes that are often used for cooking shellfish.

Food that might be contaminated with norovirus should be thrown out.

Keep sick infants and children out of areas where food is being handled and prepared.

When You Are Sick, Do Not Prepare Food Or Care For Others Who Are Sick

You should not prepare food for others or provide healthcare while you are sick and for at least 2 days after symptoms stop. This also applies to sick workers in settings such as schools and daycares where they may expose people to norovirus.

Many local and state health departments require that food workers and preparers with norovirus illness not work until at least 48 hours after symptoms stop. If you were recently sick, you can be given different duties in the restaurant, such as working at a cash register or hosting.

Clean And Disinfect Contaminated Surfaces

After throwing up or having diarrhea, immediately clean and disinfect contaminated surfaces. Use a chlorine bleach solution with a concentration of 1000–5000 ppm (5–25 tablespoons of household bleach [5.25%] per gallon of water) or other disinfectant registered as effective against norovirus by the Environmental Protection Agency (EPA).

Note: Evidence for efficacy of a cleaning agent against norovirus is usually based on studies using feline calicivirus (FCV)—a virus related to norovirus—as a surrogate. However, FCV and norovirus exhibit different physiochemical properties; thus, it is unclear whether inactivation of FCV by a specific cleaning agent reflects efficacy of such solutions against norovirus.

Wash Laundry Thoroughly

Immediately remove and wash clothes or linens that may be contaminated with vomit or stool (feces).

You should:

  • handle soiled items carefully without agitating them,
  • wear rubber or disposable gloves while handling soiled items and wash your hands after, and
  • wash the items with detergent at the maximum available cycle length then machine dry them.

Norovirus Treatment

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There is no specific medicine to treat people with norovirus illness. Norovirus infection cannot be treated with antibiotics because it is a viral (not a bacterial) infection.

If you have norovirus illness, you should drink plenty of liquids to replace fluid lost from throwing up and diarrhea. This will help prevent dehydration.

Sports drinks and other drinks without caffeine or alcohol can help with mild dehydration. But, these drinks may not replace important nutrients and minerals. Oral rehydration fluids that you can get over the counter are most helpful for mild dehydration.

Dehydration can lead to serious problems. Severe dehydration may require hospitalization for treatment with fluids given through your vein (intravenous or IV fluids). If you think you or someone you are caring for is severely dehydrated, call the doctor.

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