Barbara Rohrs
A common statement often heard when unwelcome diarrhea occurs is, "It must be something I ate." Despite the fact that America has the safest food supply in the world, the truth is, the food we eat can make us sick if not properly cared for at home. Usually it can be traced to improper handling somewhere along the line.
Norwalk Virus is part of a family of unclassified, small, round-structured viruses. The family consists of several distinct groups of viruses that have been named after the places where the outbreaks occurred. In the United States, the Norwalk and Montgomery County viruses are related but distinct from the Hawaii and Snow Mountain viruses.
Common names of the illness caused by the Norwalk and Norwalk-like viruses are viral gastroenteritis, acute nonbacterial gastroenteritis, food poisoning, and food infection.
Of viruses, only the common cold is reported more often than viral gastroenteritis.
Usual symptoms include nausea, vomiting, diarrhea, and abdominal pain. Headache and low-grade fever may also accompany this disease. The disease is usually mild and brief. It will develop 24 to 48 hours after contaminated food or water is eaten and lasts for 24 to 60 hours.
The foods most often causing Norwalk-like virus outbreaks are shellfish and salad ingredients. Water is the most common source of outbreaks and may include water from municipal supplies, wells, recreational lakes, swimming pools, and water stored aboard cruise ships.
The good news about this virus is that it doesn't multiply in foods like many other bacteria do. Also, this virus is destroyed by thorough cooking. To avoid this illness, make sure the food you eat is cooked completely. If you are traveling in an area that appears to have polluted water, drink pasteurized milk or bottled beverages without ice.
Anyone who eats food contaminated with this virus is susceptible to an infection. However, it is possible to be immune to this disease. If you have had this type of food illness within the last two years you may be immune. Immunity is not permanent and reinfection can occur. The disease is more frequent in adults and older children than in very young children.
1. National Center for Disease Control, Center for Disease Control and Prevention
2. U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Foodborne pathogenic Microorganisms and Natural Toxins Handbook, The Bad Bug Book.
For more information on food borne illness, contact your local county Extension agent. See also the additional fact sheets in this series.
Large outbreaks of gastroenteritis which occurred in Pennsylvania and Delaware in 1987 were caused by Norwalk virus. A contaminated well was the source of both outbreaks. In Pennsylvania, the ice was used at a football game and at a cocktail party in Delaware. Norwalk virus is also suspected to have caused an outbreak aboard a cruise ship in Hawaii. Fresh fruits were probably the source of this contamination.
Source: Bad Bug Book
This material is based on work supported by the Extension Service, U.S. Department of Agriculture, under special project number 96-EFSF-0-3500.
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