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Food Safety Competencies
for Educators:
A Focus on Noroviruses
Angela M. Fraser, Ph.D.
Associate Professor/Food Safety Education
Specialist
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Global Foodborne Disease
• Widespread health problem
• Important cause of reduced economic productivity
• Major cause of infant and childhood mortality in
developing nations
• Children (<5 years) suffer ~1.5 billion annual episodes of
diarrhea leading to three million premature deaths.
• 5-10% of the population in industrialized counties
affected each year.
SOURCE: WHO, 2005
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Food Safety
• Access to nutritionally adequate and safe food is a
basic human right and the underpinning of a secure,
stable society.
• Food safety must be given higher priority by
governments, industry, and consumers.
SOURCE: FAO/WHO International Conference on Nutrition (Rome, 1992)
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Changes in Eating Patterns
• Preference for fresh and minimally processed foods;
• Longer interval between processing and
consumption of foods;
• More people eating out; and
• Increased dependence on prepared/convenience
foods.
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Other Reasons for
Increased FBD
• Expanding urbanization;
• Insufficient access to safe water and facilities for
safe food preparation;
• International travel; and
• Deliberate contamination and natural and
manmade disasters.
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Common Symptoms
• Common symptoms of
foodborne illness are:
• diarrhea
• vomiting
• sore throat with fever
• jaundice
• Chronic conditions:
•
•
•
•
•
Arthritis
Autoimmune thyroid disease
Inflammatory bowel disease
Renal disease
Neural and neuromuscular
disorders
• Heart and vascular disease
• Nutritional disturbances
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Factors that increase
susceptibility to FBD
•
•
•
•
Age
General health
Pregnancy
Medications -- overthe-counter or
prescription
• Metabolic disorders
• Alcoholism, cirrhosis,
hemochromatosis
•
•
•
•
•
•
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Taking antacids
Nutritional status
Immune competence
Surgical history
Occupation
Amount of food
consumed
Foodborne Disease in U.S. (2011)
• CDC estimates that each year:
o 1 out of 6 Americans (or 48 million people) sick
with a foodborne illness;
o 128,000 are hospitalized; and
o 3,000 die.
• CDC has estimates for two major groups of
foodborne disease:
o Known foodborne pathogens (31 pathogens)
o Unknown pathogens
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Estimated Annual Number of
Foodborne Illnesses (CDC, 2011)
Foodborne
agents
Number of
illnesses
%
Number of
hospitalizations
%
Number
of deaths
%
31 known
pathogens
9.4 million
20
55,961
44
1,351
44
Unknown
pathogens
38.4 million
80
71,878
56
1,686
56
TOTAL
47.8 million 100
127,839
100
3,037
100
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Top Five Pathogens Causing
Foodborne Illness (CDC, 2011)
Pathogen
Estimated annual
number of illnesses
%
Norovirus
5,461,731
58
Salmonella, nontyphoidal
1,027,561
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Clostridium perfringens
965,958
10
Campylobacter spp.
845,024
9
Staphylococcus aureus
241,148
3
SUBTOTAL
8,541,422
91
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Top Five Pathogens Resulting in
Hospitalization (CDC, 2011)
Pathogen
Estimated annual
number of
hospitalizations
%
Salmonella, nontyphoidal
19,336
35
Norovirus
14,663
26
Campylobacter spp.
8,463
15
Toxoplasma gondii
4,428
8
E. coli (STEC) 0157
2,138
4
SUBTOTAL
49,028
88
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Top Five Pathogens Causing
Death (CDC, 2011)
Pathogen
Salmonella, nontyphoidal
Toxoplasma gondii
Listeria monocytogenes
Norovirus
Campylobacter spp.
SUBTOTAL
Estimated annual
number of deaths
378
327
255
149
76
1,185
12
%
28
24
19
11
6
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Norovirus – The Perfect
Pathogen
• Infectious Dose
• Highly contagious
• Estimated infectious dose = 10 to 100 viral particles
• Minute amounts of fecal matter containing NoV can be
transmitted via hands, food, objects, aerosols, or water.
• Viral shedding occurs at high levels
• 2.2 x 104 to 7.7 x 1010 viruses/gram (millions)
• Shedding can persist for weeks
• 25% of infected individuals shed for three weeks
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Clinical Presentation
• Incubation:
• 24 to 48 hours but cases can occur within 12 hours of exposure.
• Length of illness: 24 to 72 hours
• Limited immunity
• May be strain-specific and lasts only a few months.
• Individuals likely to be repeatedly infected throughout their
lifetimes.
• Recent evidence also suggests that susceptibility to infection may
be genetically determined.
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Symptoms
• Acute-onset vomiting, watery non-bloody diarrhea with
abdominal cramps, and nausea.
• Low-grade fever occasionally occurs.
• Diarrhea is more common than vomiting in children.
• Rarely fatal but dehydration is the most common
complication, especially among the young and elderly, and
may require medical attention.
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Illness Facts
• An illness episode (vomiting or diarrhea) can
possibly infect 50-70% of all persons within a 4
meter radius through aerosol droplets.
• One vomit episode can contain in excess of
30,000,000 viral particles.
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Stable in Environment and on Food
• Household surfaces: Can survive on environmental
surfaces over prolonged periods (2 to >12 days).
• Cloth: Viruses appears to survive better on cloth than
on paper.
• Vegetables: May persist under normal storage
conditions over time.
• Water: Can survive for months.
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Resistance and Survival
• Resistant to routine sanitizing/disinfection
methods.
• Can survive in up to 10 ppm chlorine, which is in excess
of levels routinely present in public water systems.
• Can survive freezing.
• Can survive temperatures as high as 60°C (140oF).
• Associated with illness after eating steamed
shellfish.
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Multiple Modes of NoV
Transmission
•
•
•
•
Person-to-person – 66% outbreaks
Food -- 26% outbreaks
Water – 0.1% outbreaks
Environmental surfaces – 0.3% outbreaks
SOURCE: Reported to NORS (2009-2010; N=1910)
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Attribution of Foodborne
OUTBREAKS Norovirus
ILLNESSES/OUTBREAK
No. (%)
Median (Range)
Outbreaks (CDC, 2001-2008)
FOOD
Simple FoodA
511 (15)
17 (2-425)
Leafy Greens
119 (23)
15 (3-128)
Meat-PoultryB
81 (16)
13 (2-77)
Fruits-Nuts
57 (11)
23 (2-148)
Mollusks
47 (9)
7 (2-49)
Other ProduceC
26 (5)
18 (2-92)
Other Commodity Group
175 (34)
19 (2-425)
Complex Food (multiple commodities)
786 (24)
17 (2-400)
No Food Implicated
2030 (61)
16 (2-1436)
TOTAL
3327 (100)
16 (2-1436)
Based on 511 simple food outbreaks
Includes beef, game, pork, and poultry
C Includes fungi, root, sprout, vine-stalk, and otherwise unspecified produce
A
B
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Setting of Norovirus Outbreaks
•
•
•
•
•
•
Long-term care – 60% outbreaks
Restaurant/banquet facility – 19% outbreaks
School and daycare – 7% outbreaks
Hospital – 3% outbreaks
Private home – 2% outbreaks
Other – 9% outbreaks
SOURCE: NORS, 2009-2010 (N=1500)
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Role of the Food Handler
• Food handler as a source of NoV
• Implicated source -- 53% outbreaks
• Potentially contributed – 29% outbreaks
• Not implicated – 18% outbreaks
• Asymptomatic infection may occur in as many as
30% of infections.
• Food handlers can return to work after 48 hours
without any symptoms or with written medical
note that free of the infection (FDA Food Code).
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Critical Prevention Strategies
•
•
•
•
•
Wash your hands often.
Rinse fruits and vegetables.
Cook shellfish thoroughly.
Clean surfaces and wash laundry.
When sick, do not prepare food for others.
SOURCE: www.cdc.gov/norovirus
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Removal of Feces and Vomitus
• Supplies:
• Covered 2½-5 gallon bucket
• Gloves, mask, gown, safety
glasses, booties
• Disinfectant in 1 liter/quart
spray bottle
• Absorbent powder or gel
• Scraper, dust pan
• Paper towels/disposable rags
• Red plastic biohazard bags
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Removal of Diarrhea and Vomitus
• Put on proper personal protective equipment.
• Block off affected space to prevent re-entry.
• Cover spill with absorbent powder/disposable towels to
soak up fluid.
• Scoop up the solidified powder or soaked towels, and
place them in a sealable plastic bag.
• Cover area with disinfectant soaked paper towels or rags
for 5-10 minutes or let air dry.
• Wipe up residual disinfectant with paper towels.
• Remove all personal protective equipment.
• Dispose of bag in accordance with local regulations.
• Wash hands thoroughly.
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Treatment of Surfaces
Contaminated by Diarrhea and/or
Vomitus
• Steam clean soiled carpets and upholstery after
chemical disinfection
• Must reach 70°C (158oF), for 5 minutes at the
contaminated surface.
• Air dry rugs and furniture in sunlight.
• Promptly bag and clean soiled linens or dispose as
hazardous waste.
• Wash laundry at 60oF (140oF), or twice at 40oF (104oF).
• Disinfect with chlorine bleach solution with a
concentration of 1000-5000 ppm (5-25 tablespoons of
household bleach [5.25%] per gallon of water).
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Acknowledgements
This material is based upon work supported by the National Institute
of Food and Agriculture, U.S. Department of Agriculture, under
Agreement No. 2011-68003-30395. Any opinions, findings,
conclusions or recommendations expressed in this publication are
those of the author(s) and do not necessarily reflect the view of the
U.S. Department of Agriculture.
For more information about NoroCORE, go to: norocore.ncsu.edu
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