Know Your Noroviruses

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Norovirus, frequently described as the “stomach flu,” is a highly contagious virus that can be passed through contaminated water and food supplies, as well as by other infected individuals. It mainly leads to stomach and intestine inflammation, which can then cause acute bacterial gastroenteritis. Individuals infected with noroviruses can also experience severe diarrhea and vomiting, as well as weight loss, low-grade fevers and abdominal cramps.

Norovirus is widespread, and anyone can be infected by it. No one is simply immune to a norovirus, as the virus infects most people multiple times throughout their lifetime. Although not particularly serious, it can be more severe for younger children and older adults. Today, norovirus is the most common cause of gastroenteritis in the U.S., as about 21 million adults become infected with the virus annually. On average, about 70,000 people are hospitalized each year, with about 800 deaths resulting from the most severe cases.

Although there is only one species of Norovirus called Norwalk virus, it has several different strains, including the Hawaii virus, Snow Mountain virus, Mexico virus, Desert Shield virus, Southampton virus and the Lordsdale virus. As noroviruses can be classified into five different genogroups, different strains have slightly different pathologies, although the symptoms are mainly the same.

Illnesses caused by Noroviruses

The following are some of most common forms of illnesses caused by noroviruses:

  • “Stomach Flu” or Viral Gastroenteritis: Viral gastroenteritis results from the inflammation of the stomach and causes severe diarrhea and vomiting. It usually occurs when people eat contaminated food and water. There are several different viruses that cause viral gastroenteritis, including noroviruses.
  • Food Poisoning: Food poisoning occurs when people eat food or drink water contaminated with bacteria, parasites, viruses or germs. Although most cases of food poisoning arise from eating common bacteria like Staphylococcus or E.coli, noroviruses can also cause food poisonings. The most common symptoms of food poisoning are diarrhea, abdominal cramps, headaches, nausea, vomiting and fevers.
  • Calicivirus Infections: This type of viral infection in the stomach is commonly caused through eating contaminated foods and water. Noroviruses are the most likely source of these infections, although Sapoviruses also cause caliciviruses.

How People Become Infected

Although they can be extremely uncomfortable, illnesses caused by noroviruses are not usually life threatening. The best way to prevent getting sick from noroviruses is making sure to disinfect your hands with soap and water before you eat, as noroviruses are resilient and can stay alive outside of your body for two weeks or more. Alcohol-based hand sanitizers are also useful to carry around, especially when traveling. As noroviruses can be found on fruit, meat, and vegetables, food should be carefully washed before it is consumed or cooked. Also, as the virus is highly contagious, those who are infected should not prepare food or care for others while they are sick. It takes about two to three days to recover from the illnesses caused by a norovirus, so infected individuals should stay home from work while recovering. If you throw up or have diarrhea, you should immediately clean and disinfect all contaminated areas using a chlorine bleach solution.

Additional Resources

If you are interested in learning more about noroviruses, how they spread, their symptoms and treatments, the following is a list of links that explore these topics related to norovirus.

  • CDC, Noroviruses: The Center for Disease Control provides an excellent overview of norovirus, including its causes, treatments and preventions.
  • NHS Choices, Norovirus: England’s National Health Service offers information on noroviruses. The website includes a short video, as well as details of relevant symptoms, treatment and prevention measures.
  • Food Safety Research Information Office, Norwalk Virus: Provided by the United States Department of Agriculture (USDA), this website provides a directory of press releases, articles, resources, and fact sheets related to noroviruses.