Norwalk Virus Scott VasporyCraig Pritch October 4, 2005.

Norwalk VirusNorwalk Virus

Scott Vaspory Craig Pritch

October 4, 2005

History of the virusMorphologySymptomsTransmissionPrevention

Norwalk Virus

Introduction to the Norwalk Virus

Norwalk – genus name for original Norwalk virus and other Norwalk-like viruses. Family Calicivirus.

Calicivirae found worldwide, infecting humans, primates, and cattle, among others.

Increasingly being recognized as leading cause of food borne illness.

History

Virus first identified in Norwalk, Ohio, 1973.

Noted to commonly be a problem on cruise ships.

Associated with contaminated food or water supplies.

Physiology

(+) ssRNA, nonenveloped virus. ~ 7.4 - 8.3 kb Many different strains.

Morphology

Nonenveloped capsid/nucleocapsid.

Icosahedral, 35-39 nm diameter

Picture: Norwalk virus, left and middle. Unspecified Calicivirus, right.

Genome Organization

ORF1 – polyprotein – similar to helicase, RNA polymerase of polio and RNA viruses

ORF2 – capsid protein

ORF3 – codes for protein of unknown function

Infection

Noroviruses found in stool and vomit of infected.

Very contagious – infection via eating contaminated food, contact with sick individual or contaminated surfaces.

Symptoms

Acute gastroenteritis. Illness begins suddenly, from 12-48 hours

after ingestion. Brief illness period.Very young, elderly, and those with

weakened immune systems may experience more severe symptoms.

Infectiousness may last up to 2 weeks, no evidence of long-term carriers.

Diagnosis

Electron MicroscopeRT-PCRELISA

Calicivirus is not easily studied. No efficient techniques have been developed to culture it in a lab setting.

Prevention

References

• Büchen-Osmond, C. (Ed), (2003). 00.012. Caliciviridae. In: ICTVdB - The Universal Virus Database, version 3. ICTVdB Management, Columbia University, New York, NY, USA.

• CDC. accessed September 29, 2005. Norovirus. http://www.cdc.gov/ncidod/dvrd/revb/gastro/norovirus-qa.htm 

• Directors of Health Promotion and Education. Accessed September 29, 2005. Norwalk Virus Infection. http://www.astdhpphe.org/infect/norwalk.html

• Microbiology Department, Mount Sinai Hospital. Accessed October 2, 2005. Norwalk and Noroviruses. http://microbiology.mtsinai.on.ca/bug/norwalk/nor-bug.shtml

Scott Vaspory

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Craig Pritch

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