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Running head: assignment #6
Norovirus Infection
ASSIGNMENT #6
Microbiology 212
Niagara University
Heather Grimwood
0893782
Professor: M. Gallo
Due Date: October 18, 2013
ASSIGNMENT #6-GRIMWOOD
Annually, millions of people contract the infamous ‘winter bug’ known as Norovirus.
During this time more time is spent indoors during the winter months and in closer proximity to
one another. Originating from the Norwalk virus, after the first outbreak was confirmed in
Norwalk, Ohio in 1972, symptoms can be quite vague that may be the cause for confusion when
making a diagnosis. Symptoms may range from acute vomiting, diarrhea, fever, abdominal
cramps, myalgia and headache that may last anywhere from 24-60 hours. The transmission of
contaminants is made through food, human to human contact and inanimate surfaces that offer
cross-contamination opportunities. “…Norovirus is so contagious that people can become ill
even through contact with viral particles in the air.” (Bernstein 2013) Most food-borne cases are
not reported. Simple hand-washing techniques, cooking seafood thoroughly and washing fruits
and vegetables prior to handling and eating disrupts the cycle of microorganism transmission.
According to the Centers for Disease Control and Prevention, (2013), Norovirus can be
found in your vomit and stool even before you start feeling sick. The virus can stay in your stool
for 2 weeks or more after you feel better. All the more important to stress the washing of hands
vigorously with soap and water for at least 30 seconds after using the washroom, before handling
food and whenever the hands are soiled. Simply using hand sanitizer is not sufficient enough in
removing most types of microorganisms. “Viral diarrhea is an especially common cause of
mortality among children less than five years of age in developing countries, with an estimated
1.5 billion episodes and 1.5 million to 2.5 million deaths estimated to occur annually.” (Willey et
al., 2014 878). Dehydration may complicate the illness due to severe fluid loss.
Norovirus is classified as belonging to the Caliciviridae family. It lacks a viral envelope
and can be sanitized from inanimate surfaces. The virus can live on surfaces outside of a human
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ASSIGNMENT #6-GRIMWOOD
host for long periods of time. Continuous cleaning is recommended to decrease reproduction of
the virus. The Norwalk virus capsid can be visualized under an electron microscope. Ingestion
of the Norovirus pathogen enters the gastrointestinal system and grows in the host. After an
incubation period of approximately 1-2 days the virus invades the epithelial cells in the human
body at the upper intestinal villi. Toxins are released that cause a disturbance in the digestion
process. Sodium transport impairments typically follow. Electrolytes may be affected if fluids
are restricted which can be a leading cause of cardiac dysrhythmia. The National Institute of
Allergy and Infectious Diseases, (2010), recommend plenty of bed rest and drinking lots of fluids
as therapeutic treatment guidelines. Antibiotics are not indicated as they have no effect on
viruses.
Clinical trials have been underway and according to researchers continue to provide
promising results. Bernstein, (2013), reports if the vaccine continues to prove as effective as our
initial results indicate, it could be used for specific populations or situations-in those at higher
risk of severe disease such as the elderly or at high risk for infection or transmission such as in
day care, people going on a cruise, those in nursing homes or in the military. Overall, the results
showed a 52% reduction in symptoms after subjects were exposed to the Norovirus in a clinical
setting. Diagnostic methods for confirmation of Norovirus focus on a physical and symptomatic
assessment by a clinical practitioner. If laboratory testing is required a detection of viral load
can be reported through viral Ribonucleic acid (RNA) or antigens that use reverse transcriptionpolymerase chain reaction (RT-PCR) assays. Stool samples, vomitus, foods and water may be
screened for confirmation of the virus.
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References
Bernstein, D. Norovirus vaccine reduces symptoms by half. Medical News Today. October 2013.
Willey, J., Sherwood, L., Woolverton, C. (2014). Prescott’s microbiology, 9th (ED.). McGrawHill Companies, Inc., New York.
Centers for Disease Control and Prevention. 2013.
http://www.cdc.gov/norovirus/preventing-infection.html
National Institute of Allergy and Infectious Diseases. 2010.
http://www.niaid.nih.gov/topics/norovirus/
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