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Norwalk virus
Named after town, Norwalk Ohio where outbreak of viral gastroenteritis occurred
Epidemiology:
1) transmitted by fecal oral route
2) shellfish and salads are common culprits
3) ill food handlers also culprits
4) waterbourne outbreaks from municipal supplies, wells, recreational lakes, swimming pools, ice machines
5) outbreaks on cruise ships
6) second to the common cold as a cause of illness in the USA
7) incubation time is > 14 hours
Pathology:
1) food poisoning
2) non-inflammatory diarrhea
Clinical manifestations:
1) incubation time 24-48 hours
2) gastroenteritis, non-inflammatory diarrhea
3) nausea, vomiting
4) abdominal pain
5) fever (50%)
6) symptoms may persist for several days
7) dehydration may be life-threatening the young, elderly, immunocompromised
Laboratory:
1) RT-PCR for norovirus RNA
2) ELISA lacks sensitivity & specificity
3) single-stranded RNA virus
a) no envelope
b) size: 8 kilobases in size
4) see norovirus (no Loincs for Norwalk virus found)
Management:
1) self-limiting disorder
2) treatment is supportive
- dehydration is a concern
3) handwashing & surface sanitization are the cornerstones of infection control
General
norovirus (Norwalk-like virus, winter vomiting disease)
Properties
KINGDOM: virus
GENOME-TYPE: RNA
SINGLE-STRANDED
POSITIVE-STRAND
GENOME-SIZE: 8 kB
ENVELOPE: NONE
CAPSID-SYMMETRY: ICOSAHEDRAL
References
- Harrison's Principles of Internal Medicine, 13th ed.
Isselbacher et al (eds), McGraw-Hill Inc. NY,
1994, pg 469
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed)
Lippincott-Raven, Philadelphia, 1998, pg 536
- Clinical Diagnosis & Management by Laboratory Methods,
19th edition, J.B. Henry (ed), W.B. Saunders Co.,
Philadelphia, PA. 1996, pg 1164-65
- Medical Knowledge Self Assessment Program (MKSAP) 15, 16.
American College of Physicians, Philadelphia 2009, 2012