Norwalk Virus: Your A-to-Z Guide from Diagnosis to Treatment to Prevention

Young boy in a cap. Norwalk virus.What is norwalk virus?

Norwalk virus was first identified as the cause of an outbreak of gastroenteritis among children at a school in Norwalk, Ohio – and among their teachers and their families.
Norwalk virus is a significant cause of gastroenteritis outbreaks in schools, day-cares, summer camps, restaurants, and cruise ships. It is also a significant cause of gastroenteritis in the absence of an outbreak. In addition, Norwalk virus is a significant cause of food poisoning.

Who gets it?

Anyone can get Norwalk virus, from the nursery to the nursing home, but those at highest risk are children under 4. Outbreaks often occur in settings where there is close contact between many children. The virus is found in stool and on hands and surfaces that have had contact with stool. Norwalk food poisoning has most often been associated with contaminated ice, water, raw shellfish, salads, sandwiches, and cookies.

The virus is destroyed by cooking, but not by freezing

What are the symptoms?

Diarrhea and vomiting are the hallmark symptoms of Norwalk virus infection. These may be accompanied by fever, headache, muscle aches, abdominal cramps, and generally feeling crummy.

Is it contagious?

Norwalk virus is quite contagious, and may be spread via the fecal-oral route, through direct contact,through infected fomites, or through contaminated food or water.

How long does it last?

Symptoms usually begin 12 hours to 4 days after having been exposed. The illness may last for as little as a day, or as long as 2 weeks.

How is it diagnosed?

The diagnosis is usually based on history and physical examination. Stool tests are available that can detect the virus.

How is it treated?

Usually, the only treatment is to prevent or treat dehydration by drinking plenty of fluids. Oral rehydration solutions such as Pedialyte may be used. In more severe cases, intravenous fluids may be needed.

Antibiotics usually make the situation worse.

How can it be prevented?

Wash hands before preparing or serving foods. Have someone else prepare the food if you have cramps, nausea, vomiting, or diarrhea, or have sores on your hands. Children, and those who care for them, should wash thoroughly before eating and after toileting.

For further prevention ideas, see the articles on fecal-oral transmission, contact transmission, and fomites.

Related concepts:

Calciviruses, Tummy flu, Stomach flu.

Dr. Alan Greene

Dr. Greene is a practicing physician, author, national and international TEDx speaker, and global health advocate. He is a graduate of Princeton University and University of California San Francisco.

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