What are Norwalk Viruses (Noroviruses)?Noroviruses are a group of viruses that cause the "stomach flu", "stomach bug", or gastroenteritis in people. Although people often refer to noroviruses (or the Norwalk virus) as the "flu", the virus is not the influenza virus, and getting a flu shot will not prevent it. Sometimes a norovirus is referred to as food poisoning, but it is not always transmitted in food, and there are other types of food poisoning not in the norovirus family. The symptoms come on very suddenly, but the illness is very brief, usually only one to three days. Although the norovirus is very nasty while you have it, most people do not have adverse long-term health effects.
The Norwalk virus was named for Norwalk, Ohio, where there was an outbreak in the 1970's. Today, similar viruses are called noroviruses or Norwalk-like viruses. Whatever they are named, this stomach virus ranks second (behind the common cold) in the occurrence of viral illnesses in the United States. The Centers for Disease Control (CDC) reported over 267 million cases of diarrhea in 2000, and estimates about 5 to 17 percent of these may have been caused by a Norwalk virus. Cruise ships are not the only place where you can pick up this nasty bug! Of the 348 outbreaks reported to the CDC between 1996 and 2000, only 10 percent were in vacation settings such as cruise ships. Restaurants, nursing homes, hospitals, and daycare centers are the most likely places you will get a norovirus.
How Do People Become Infected with the Norwalk Virus (Norovirus)?Noroviruses are found in the feces or vomit of infected people. People can become infected with the virus in several ways, including:
- eating food or drinking liquids that are contaminated with norovirus;
- touching surfaces (such as doorknobs) or objects (such as eating utensils) contaminated with norovirus, and then placing their hand in their mouth;
- having direct contact with a person who is infected and showing symptoms
The norovirus is very contagious and can spread rapidly throughout cruise ships. Like the common cold, the norovirus has many different strains, which makes it difficult for a person's body to develop long-lasting immunity. Therefore, norovirus illness can recur throughout a person's lifetime. In addition, some people are more likely to become infected and develop more severe illness than others due to genetic factors.
When Do Norwalk Virus Symptoms Appear?Symptoms of Norwalk virus or norovirus illness usually begin about 24 to 48 hours after exposure to the virus, but they can appear as early as 12 hours after ingestion. People infected with norovirus are contagious from the moment they begin feeling ill until at least 3 days after recovery. Some people may be contagious for as long as 2 weeks. Therefore, it is particularly important for people to use good handwashing practices after they have recently recovered from a Norwalk virus.
What Treatment Is Available for People with a Norwalk Virus Infection?Since the Norwalk virus is not bacterial, antibiotics are ineffective in treating the illness. Unfortunately, like the common cold, there is no antiviral medication that works against the Norwalk virus and there is no vaccine to prevent infection. If you are vomiting or have diarrhea, you should try to drink plenty of fluids to prevent dehydration, which is the the most serious health effect that can result from Norwalk virus or norovirus infection.
Can a Norwalk Virus Infections Be Prevented?You can decrease your chance of coming in contact with the Norwalk Virus or norovirus on a cruise ship by following these preventive steps:
- Frequently wash your hands, especially after using the toilet, changing diapers, and before eating or preparing food.
- Use a bleach-based cleanser to thoroughly clean and disinfect contaminated surfaces immediately after an illness episode.
- Immediately remove and wash clothing or linens (with hot water and soap) that may be contaminated with virus after an illness episode
- Flush or discard any vomitus and/or stool in the toilet and make sure that the surrounding area is kept clean.
Getting a Norwalk-type virus or norovirus can ruin your vacation, but the fear of getting this virus should not keep you at home. Use proper sanitation procedures and remember that you are just as likely to get sick in your hometown!