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CLEANING UP NOROVIRUS OUTBREAKS

Edited by: Stephanie Wallner, M.S., Mary Schroeder, M.S., R.D, Pat Kendall, Ph.D., R.D., Colorado State - Fall 2006

Most people think of bacteria like Salmonella and E. coli when they think of foodborne illness outbreaks, but a group of viruses, collectively called noroviruses, are thought to account for at least 50% of all cases of foodborne illness. Also known as caliciviruses or Norwalk-like viruses, noroviruses are a group of related, single-stranded RNA, non-envelope viruses that can cause acute gastroenteritis in humans (1).

Noroviruses can be transmitted through contaminated food and water, either person-to-person or through the fecal-oral route, and can also spread through contact with contaminated surfaces. The incubation period is typically about 12 to 48 hours, and the resulting illness is usually characterized by nausea, vomiting, diarrhea, abdominal cramps, headache, dehydration, and fever lasting 24 to 60 hours. Noroviruses are very contagious, a main reason why controlled environments such as cruise ships are ideal for the spread of noroviruses (2, 3).

Currently, there are no disinfectants specifically approved by the Environmental Protection Agency (EPA) that target and destroy noroviruses. There are, however, several different virucides that are being tested for effectiveness. The EPA evaluates the ability of the test agents to inactivate a virus similar to norovirus (4). The test agent is considered an acceptable virucide if there is a 4-log reduction in the infectious virus. The only product currently considered effective as a disinfecting agent is a peroxygen compound called Virkon-S (1). This compound, when used according to the manufacturer's specific instructions, can be used to disinfect contaminated surfaces.

The CDC also suggests that other compounds may have potential for disinfecting areas contaminated with Noroviruses (1). Ammonium compounds are often used to clean surfaces and floors after virus contamination, although their effectiveness has not been proven. Phenolic-based disinfectants have been shown to be effective against noroviruses in laboratories, but extremely high concentrations of these compounds may be required. Heat disinfection, or pasteurization, is an option for surfaces that should not be exposed to chemical disinfectants; temperatures of 140 degrees F or higher have been effective in laboratory conditions.

Sources:

1. Norovirus in Healthcare Facilities Fact Sheet. Centers for Disease Control and Prevention. Available at: http://www.cdc.gov/ncidod/dhqp/id_norovirusFS.html. Accessed April 7, 2006.
2. CDC Answers Your Questions About Noroviruses and Food Handlers. Centers for Disease Control and Prevention. Available at: http://www.cdc.gov/ncidod/dvrd/revb/gastro/noro-foodhandlers.pdf. Accessed April 7, 2006.
3. CDC Technical Fact Sheet About Noroviruses. Centers for Disease Control and Prevention. Available at: http://www.cdc.gov/ncidod/dvrd/revb/gastro/noro-factsheet.pdf. Accessed April 7, 2006.
4. Initial Virucidal Effectiveness Test. United States Environmental Protection Agency, Antimicrobials Division. Available at: http://www.epa.gov/oppad001/pdf_files/fcv1_initial_surf_pcol.pdf. Accessed April 7, 2006.

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