Norwalk Virus Scott VasporyCraig Pritch October 4, 2005
History of the virus Morphology Symptoms Transmission Prevention 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, Noted to commonly be a problem on cruise ships. Associated with contaminated food or water supplies.
Physiology (+) ssRNA, nonenveloped virus. ~ kb Many different strains.
Morphology Nonenveloped capsid/nucleocapsid. Icosahedral, 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 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 Microscope RT-PCR ELISA 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) Caliciviridae. In: ICTVdB - The Universal Virus Database, version 3. ICTVdB Management, Columbia University, New York, NY, USA. CDC. accessed September 29, Norovirus. Directors of Health Promotion and Education. Accessed September 29, Norwalk Virus Infection. Microbiology Department, Mount Sinai Hospital. Accessed October 2, Norwalk and Noroviruses.
Scott Vaspory Craig Pritch