Norwalk and Noroviruses
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Personal prevention methods

Immunity to Norwalk and Noroviruses is strain-specific and temporary, so everyone should take precautions to prevent the spread of Norwalk virus to others.

Frequent hand washing with soap and running water is important, especially after using the washroom and before handling food. Prompt disinfecting of contaminated surfaces and soiled clothing will also help prevent the spread of the disease. Regular household bleach based cleaners are effective.

Thorough cooking destroys Norwalk virus, so make sure the food you eat is cooked completely. Remember that the virus can survive for 30 minutes at 60°C. When preparing food, do not cross-contaminate. If you suspect that the water supply is polluted while travelling, choose to drink pasteurized milk or bottled beverages without ice.



There is currently no vaccine available for prevention of Norovirus infection. Factors that make creation of a Norwalk vaccine difficult include:

  • Noroviruses are currently non-cultivatable in any tissue culture or animal system.
  • There are multiple genetic and antigenic types of Norovirus.
  • Immunity to Noroviruses are short-term and strain-specific. Re-infection can occur.

Large-scale prevention methods

Food handlers with symptoms of Norwalk and Norovirus-related illness should be excluded from food handling and preparation. Programs that educate and train food handlers and people who work in places where there is a high risk of Norwalk virus outbreaks will help to prevent disease and transmission. Regulation and enforcement of proper disposal of human sewage will help prevent outbreaks caused by contamination of shellfish, etc by water.


Infection Control in Healthcare Institutions

Prevention of outbreaks in institutions depends on good food handling practices, and compliance with hand washing on the part of staff. Hand hygiene procedures should be reviewed by all staff members. Common touch surfaces (door handles, handrails, sink/toilet handles) should be disinfected.

Health care precautions for staff dealing with Norwalk patients include wearing gloves and gowns to protect them from contact transmission. Use of a mask is advised if there is potential for airborne transmission involving areas where gross contamination with feces and/or vomit has occurred. Since Norwalk virus can still be shed in feces up to 48 hours after symptoms disappear, ill patients must remain in their rooms until 48 hours after symptoms have disappeared. Ill staff members must be excluded from work, and should not return within 48 hours after symptoms of Norwalk have stopped.

Movement of patients and staff within the institution should be restricted. Patient transfers into and out of areas with Norovirus should be avoided. Use of part-time and casual staff who work in other areas or institutions should also be avoided. Nurses and other staff who do work in areas with Norovirus should be grouped to work exclusively in those areas. Group activities should be decreased or discontinued until the outbreak is resolved.

Hospitals and nursing homes should also maintain surveillance for clusters of gastroenteritis, so that more stringent precautions may be taken if there is evidence of transmission within the facility. Visitors and personnel should be informed of how Norwalk is spread and the personal precautions they can take.

This website has been made possible through an unrestricted educational grant from Pfizer Canada Inc.
Copyright 1999-2007 Department of Microbiology, Mount Sinai Hospital, Toronto, Canada. All rights reserved.