Download Norwalk Virus - University of Florida

Background students: English level III-IV
GPA 3.7-4.0
*80%MedScience students
came from (Middle)
€ How
do the students should develop an
outline and summary assignment
regarding any disorder in
Pathophysiology?
€ Objectives: students will be able to
1) Improve the learning skills and how
to prepare a P.Point at college level
2) Approach the GAP between High
School Pre-Med and College level
3) Enhance critical thinking proficiency
€ Materials: Magazines, Articles, TB
€ Eight
Modules /Academic year/2 for quarter
€ Outline and summarize diverse disorders
Every other week
€ Cooperative teaching process (English honor
teacher)
€ Emphasis Medical terminology
€ Small learning team (4students)ÆMonthly
project (P.Point Ptt) regarding the best
assignment, it has been chosen by the teachers
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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Case study
Investigation/Brainstorming
¾ History of the virus
¾ Background
¾ Morphology
¾ Predisposing causes/Epidemiology,
Florida
¾ Symptoms/Signs Clinical
manifestations
¾ Transmission
¾ Diagnosis/Differential diagnosis
¾ Prevention
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Dr Garcia Medical Science Academy-PBSD
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€ An
80 y.o. female presents to the ER with a
3 days history of fatigue, abdominal
cramps and bloody diarrhea. She denies
any fevers and states that 10 days ago she
was at a State Fair where she ate hotdogs,
baked beans, coleslaw, and drank fresh
apple cider. PEX: T=37 BP=140/90 P=100
ABDOMEN: generalized tenderness LABS:
WBC 12,000 Lymphocytes 65% HCT 19.0
PLTS 90,000 BUN/Cr 50/3.0 LDH 400 Total.
Bilirrubin 4.0
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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€ A)
S. aureus
€ B) Salmonella
€ C) Norwalk virus
€ D) Neisseria
€ E) E.coli O157:H7
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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¾
Norwalk – genus name for original
Norwalk virus and other Norwalklike viruses. Family Calicivirus.
¾
Calicivirae found worldwide,
infecting humans, primates, and
cattle, among others.
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Increasingly being recognized as
leading cause of food borne illness.
Nursing homes (medical Arena)
has been another place founded.
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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¾ Virus
first identified in Norwalk, Ohio,
1973.
¾ Noted to commonly be a problem on
cruise ships.
¾ Associated with contaminated food or
water supplies.
¾ Currently, It is prevalent in Nursing
homes
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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Noroviruses are a group of single-stranded RNA viruses in the
family Caliciviridae that cause acute gastroenteritis in humans.
Norwalk virus is the prototypical strain in the genus. Norovirus
infection is an important cause of acute gastroenteritis in humans
and is the most frequently implicated cause of outbreaks of viral
gastroenteritis worldwide. Noroviruses cause an estimated 20% of
all viral gastroenteritis cases in persons older than 24 months.
Norwalk virus was first associated with gastroenteritis in 1972. It
was identified by electron microscopy of stool samples that had
been saved from a 1968 gastroenteritis epidemic that occurred in
Norwalk, Ohio. In a 2-day period, acute gastroenteritis developed
in 50% of 232 students or teachers in an elementary school. The
virus initially was labeled as a small, round, structured virus, and it
was named after the city in which the outbreak occurred. Recently,
norovirus infections have made news as the cause of several
outbreaks of gastroenteritis on cruise ships.
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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The Norwalk virus is shed in the stool for 24-48 hours after
the onset of illness. Infection is spread by contaminated
water, foods and from person to person. The virus is
relatively resistant to chlorine and can contaminate
swimming pools. The virus is also relatively resistant to
heat and cooking of shellfish may not completely eliminate
the risk of infection. Outbreaks are common in closed
environments such a cruise ships and nursing homes.
Florida is the provides and ideal environment for the
spread of Norwalk virus. Swimming pools are very common
in our state and shellfish are popular among Floridians.
Finally our ports are the home to many cruise lines and
major outbreaks of Norwalk virus have become a major
problem for our cruise passengers.
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The frequency of norovirus disease in the United States is difficult to
quantify because of the lack of readily available diagnostic assays. Recent
efforts to determine the etiology of diarrheal diseases in the United States
have suggested that noroviruses cause up to 17% of community cases of
diarrhea and 7% of cases that require physician treatment.
Among 232 outbreaks of norovirus gastroenteritis reported to the Centers
for Diseases Control between 1997 and 2000, 57% were foodborne, 16%
involved person-to-person spread, 3% were waterborne, and the
remainder were unknown. The location of these outbreaks included
restaurants (36%), nursing homes (23%), schools (13%), and
resorts/cruise ships (10%). In September 2005, an outbreak of norovirus
gastroenteritis affected approximately 1000 Hurricane Katrina evacuees
in temporary facilities in Houston, Tex. This episode illustrates the
increased risk of such outbreaks in overcrowded conditions.
International
Data regarding outbreaks in developing nations are not well quantified,
but the outbreak rate in other industrial nations is similar to that of the
United States.
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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¾ (+)
ssRNA, nonenveloped virus.
¾ ~ 7.4 - 8.3 kb
¾ Many different strains.
Dr Garcia Medical Science Academy-PBSD
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¾ Nonenveloped capsid/nucleocapsid.
¾ Icosahedral, 35-39 nm diameter
Picture: Norwalk virus, left and middle. Unspecified
Calicivirus, right.
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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ORF1 – polyprotein – similar to helicase, RNA polymerase of polio and
RNA viruses
ORF2 – capsid protein
ORF3 – codes for protein of unknown function
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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¾ Noroviruses
found in stool and vomit of
infected.
¾ Very contagious – infection via eating
contaminated food, contact with sick
individual or contaminated surfaces.
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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The viruses are transmitted via the fecal-oral route. The most
common routes of infection include contact with an infected
individual or contact with contaminated food and water.
Noroviruses can also be spread via particles aerosolized with
vomiting. The viruses are highly contagious; only 100 viral
particles are likely required to establish infection. Noroviruses can
survive freezing and heating temperatures of up to 140°F. Infection
is characterized by damage to microvilli in the small intestine,
causing malabsorption. Vomiting is related to a virus-mediated
change in gastric motility and delayed gastric emptying. Notably,
no histopathologic lesions are identified in the gastric mucosa of
infected patients. Noroviruses do not invade the colon, therefore
fecal leukocytes are typically absent and hematochezia is rare.
Recurrent infections can occur throughout life because of the
diversity of norovirus strains and the lack of cross-strain or longterm immunity.
Frequency
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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¾ Acute
gastroenteritis.
¾ Illness begins suddenly, from 12-48 hours
after ingestion. Brief illness period.
¾ Very young, elderly, and those with
weakened immune systems may
experience more severe symptoms.
¾ Infectiousness may last up to 2 weeks, no
evidence of long-term carriers.
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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€ This
virus causes watery diarrhea,
abdominal cramps, nausea and
vomiting. Fever headache and muscle
aches are other common complaints.
Examination of the stool reveals no
inflammatory cells and culture is
negative for bacteria known to cause
infectious diarrhea. The disease is selflimiting usually lasting 2-6 days.
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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¾ Electron
Microscope
¾ PCR
¾ ELISA
¾ Calicivirus
is not easily studied. No
efficient techniques have been
developed to culture it in a lab setting.
Dr Garcia Medical Science Academy-PBSD
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Laboratory Studies
Isolated occurrences of gastroenteritis do not require laboratory studies.
In severe cases of gastroenteritis with suspected dehydration, the following
laboratory studies are indicated.
• Serum electrolytes
• BUN and creatinine
Detection:
• Detection can be achieved with polymerase chain reaction (PCR) or electron
microscopy. Newer diagnostic modalities such as microarrays are currently
under investigation.
• Referral laboratories typically can evaluate stool isolates for noroviruses.
• Because the studies are very costly, stool evaluation is not recommended unless
strong public health indications exist.
Epidemic outbreaks
• More than 2 people living in different households who shared a common meal
or 3 or more people living in the same household
• Stool culture for Yersinia, Shigella, Salmonella, and Campylobacter species
• Stool for occult blood
• Fecal leukocytes
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In an epidemic setting, the health department may choose to
further evaluate stool with PCR for noroviruses.
Imaging Studies
Imaging for isolated, uncomplicated gastroenteritis is not
required.
If acute abdomen or toxic ingestion is suspected, an abdominal
series is indicated.
Other Tests
If the patient is a returning international traveler, stool tests for ova
and parasites or specialized stool cultures for cholera may be
considered.
If the patient is severely immunocompromised (AIDS), stool tests
for Cyclospora, cytomegalovirus (CMV), Isospora, and
Cryptosporidium may be considered
Histologic Findings
Stool culture will be negative for infectious bacteria. Stool is
typically heme-negative and fecal leukocytes will be absent.
Vomitus will be heme-negative and nonbilious
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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Amebiasis
Gastric Outlet Obstruction
Bacterial Overgrowth Syndrome
Gastritis, Acute
Campylobacter Infections
Gastroenteritis, Bacterial
Carcinoid Tumor, Intestinal
Gastroenteritis, Viral
Cholera
Hepatitis, Viral
Clostridium Difficile Colitis
Inflammatory Bowel Disease
Crohn Disease
Irritable Bowel Syndrome
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Cryptosporidiosis
Isosporiasis
Cyclospora
Malabsorption
Cytomegalovirus
Microsporidiosis
Cytomegalovirus Colitis
Picornavirus-Overview
Diverticulitis
Pseudomembranous Colitis
Diverticulosis, Small Intestinal
Salmonellosis
Enteroviruses
Shigellosis
Eosinophilic Gastroenteritis
Ulcerative Colitis
Escherichia Coli Infections
Vibrio Infections
Food Allergies
Food Poisoning
Dr Garcia Medical Science Academy-PBSD
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€ Treatment
consists of supportive care.
Some individuals require intravenous
fluids; however most individuals are able
to prevent dehydration by drinking
fluids. No vaccine is presently
available for this virus.
Dr Garcia Medical Science Academy-PBSD
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€ Careful
and extensive cleaning of closed
environments such as ships is required.
Food handlers with diarrhea should stay
home from work and always wash their
hands. Shellfish need to be thoroughly
cooked. Children with diapers should
not be allowed in swimming pools and
pools should be periodically
hyperchlorinated.
Dr Garcia Medical Science Academy-PBSD
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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
Frederick Southwick, M.D.
Professor of Medicine and Chief of Infectious Diseases
University of Florida College of Medicine
https://www.epi.ufl.edu/?q=node/28
http://emedicine.medscape.com/article/224225-treatment
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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Dr. Jairo Garcia
[email protected]
Palm Beach School District/Fl
Dr Garcia Medical Science Academy-PBSD
9/8/2009
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