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  • Norwalk Virus

  • The Norwalk virus has turned
    love boats into sick bays.

    Norwalk and Norwalk-like viruses cause an estimated 181,000 cases of "stomach flu" each year. The viruses, which are also known as caliciviruses, are named for Norwalk, Ohio, where the first such virus was identified.

    The viruses are most commonly associated with oysters that are harvested from sewage-contaminated waters and eaten raw. Recently, the viruses have ruined cruise vacations by ravaging popular ships, and have been named as the culprits in several community outbreaks.

    How it's spread

    The only known way the Norwalk virus is spread is through the fecal matter of those who are infected. These viruses only affect people, and can't be spread by animals. They can be spread through:

    • Shellfish from waters contaminated with sewage
    • Infected people who don't wash their hands properly after using the bathroom, and then prepare food or touch food that another person might eat.
    • Water or ice that is contaminated with sewage


    The Norwalk and Norwalk-like viruses cause brief, but intense gastrointestinal distress. Symptoms usually last two to three days and may include:

    • Watery diarrhea
    • Abdominal cramps
    • Nausea
    • Headache
    • Low-grade fever

    These symptoms are not life-threatening and usually go away on their own. In certain cases, particularly in young children, symptoms can cause dehydration that may require hospital treatment.


    As with other gastrointestinal viruses, the biggest health threat is dehydration. The best treatment for Norwalk virus is to drink plenty of fluids. Antibiotics have no effect on this illness.

    Reduce your risk

    Your best protection against contracting Norwalk virus is to practice proper handwashing techniques and to only eat thoroughly cooked shellfish. Avoid any food or water that you suspect might be prepared in an unsanitary way. The U.S. Centers for Disease Control predicts that the viruses will continue to turn up until laws regarding the proper disposal of sewage, from sewage plants and by fishermen and recreational boaters, are enforced.

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