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The 2007 Norovirus Season
Food Safety Partnership
October 15, 2008
April Bogard, MPH, RS
Minnesota Department of Health
[email protected]
651.201.5076
Characteristics of Norovirus
• Highly infectious
• No long-term immunity
• Low infectious dose (10
– 100 viral particles)
• All ages at risk of
infection
• Asymptomatic infection
occurs in ~30% of
people
• More frequent in winter
months
• Cannot culture the virus
Potential Transmission
Level of NoV
• NoV is shed in the feces at levels up to
10,000,000 viral particles per gram
• One projectile vomiting incident can
include up to 30,000,000 viral particles
• Reminder: Infectious dose of NoV is
estimated to be 10 – 100 viral particles
Duration of Symptoms and
Shedding of Norovirus
• Community-based cohort study of 99
cases in the Netherlands
– all age groups represented
• Median duration of symptoms: 5 days
• Shedding (virus detected in stool)
– Day 1:
– Day 8:
– Day 15:
– Day 22:
78%
45%
35%
26%
Rockx, et al 2002
Transfer of NoV from
Contaminated Fingers
• NoV can transfer from contaminated
fingers, sequentially to 7 different
environmental surfaces.
• Secondary transfer of NoV (from
contaminated surfaces → clean fingers →
other surfaces): can transfer sequentially
to 4 different surfaces.
• Detergent cleaning, followed by rinsing
was not effective in cleaning contaminated
surfaces (unless followed by a
disinfectant).
Norovirus Outbreak
Example 1:
Minnesota Bakery
Norovirus Infections Associated
with Frosted Bakery Products, 1982
• Ill foodworker prepared 76 L of
buttercream frosting for use on ~10,000
products
• Frosting maker during 6-hour shift:
– 5 episodes of diarrhea
– 2 episodes of vomiting
Norovirus Infections Associated
with Frosted Bakery Products, 1982
• Frosting maker’s children
had GI illness onset 1, 2,
and 3 days prior to his
onset of illness
• Bare arm up to elbow in
frosting
• Estimated 3000 illnesses
(including several other
foodworkers at the
bakery)
Norovirus Infections Associated
with Frosted Bakery Products, 1982
35
30
N um ber of C ases
25
20
15
10
5
0
4
8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76
H o u rs A fte r E x p o s u re
MN Statistics (< 2005)
Confirmed Foodborne Outbreaks
Confirmed Foodborne Outbreaks,
Minnesota, 1995-2005
50
45
40
35
30
25
20
15
10
5
0
Hotline initiated
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year of Outbreak
Confirmed Foodborne Outbreaks, by
Etiology, Minnesota, 2005 (n=41)
E. coli
O157:H7
Other
Salmonella
Norovirus
Bacterial
Intoxications
Confirmed Foodborne Outbreaks,
by Setting, Minnesota, 2005 (n=41)
Church Potluck
Commercial
Product
Workplace
Private
Restaurant
0
5
10
15
20
25
30
Number of Confirmed Foodborne Outbreaks
35
Confirmed Foodborne Outbreaks,
by Contributing Factor, Minnesota, 2005 (n=41)
Unknown Contributing Factor
Histamine/Escolar
Contaminated Raw Product
Ill Attendee
Ill Foodworker
0
2
4
6
8
10 12 14 16 18 20
Number of Confirmed Foodborne Outbreaks
MN Statistics (2006)
Confirmed Foodborne Outbreaks
Confirmed Foodborne Outbreaks,
Minnesota, 1995-2005
50
45
40
35
30
25
20
15
10
5
0
Hotline initiated
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Year of Outbreak
Confirmed Foodborne Outbreaks,
Minnesota, 1995-2006
Confirmed Foodborne Outbreaks
90
80
70
60
50
40
30
20
Hotline initiated
10
0
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Year of Outbreak
Etiologies of Confirmed Foodborne
Outbreaks, Minnesota, 2006 (n=83)
Pathogen________
Norovirus
Salmonella
Scombroid
Clostridium perfringens
E. coli O157:H7
Shigella
Staphylococcus aureus
Cyclospora
Listeria
Amatoxin
No. (%)__
56 (67%)
9 (11%)
5 (6%)
5 (6%)
3 (3%)
1 (1%)
1 (1%)
1 (1%)
1 (1%)
1 (1%)
Please Note: 2006 data are preliminary and subject to change.
Confirmed Foodborne Outbreaks by Setting,
Minnesota, 2006 (n=83)
Other
Commercial
Outbreak Setting
Church
Workplace
School
Prison
Private
Caterer
Restaurant
0
5
10 15 20 25 30 35 40 45 50 55 60 65
Number of Confirmed Foodborne Outbreaks
Please Note: 2006 data are preliminary and subject to change.
Selected Norovirus Outbreak Reporting, 20061
Month
Location
Facility Type
Number Ill
Jan
Indiana
Middle School
245
Jan
Michigan
Restaurant
>430
Jan – Feb
Chicago
Hotel
>150
Feb
Minnesota
Mar
FL & CA
Cruise ships
>500
Apr
Florida
University
150
Vancouver
Assisted living
facility
55 residents &
staff (3
deaths)
Apr
1
Restaurants, hotels,
>29 outbreaks
nursing homes,
schools
As reported to CDC (by special request for information)
Norovirus Outbreak
Example 2: Minnesota Restaurant
Norovirus Outbreak After Eating at
a Restaurant in Winona
• MDH received a complaint on June 27
from a group of five that had eaten at a
Winona restaurant on June 24.
• Credit card receipts were obtained from
people who dined on June 24.
• Employees were interviewed to assess
illness and work history.
Norovirus Outbreak After Eating at
a Restaurant in Winona
• 40 patrons interviewed
– 12 patrons met the case definition
– 3 cases called or visited their health care
provider; none were hospitalized
• 48 foodworkers were interviewed
– 4 admitted having GI symptoms in the
weeks before June 24, and several stated
that “the flu” had been going around work
Norovirus Outbreak After Eating at
a Restaurant in Winona
• 4 patrons tested positive for norovirus
• 2 employees tested positive for
norovirus
• All had identical nucleic acid sequences
Outbreak of Norovirus Gastroenteritis Associated with a
Restaurant in Winona, Minnesota, June 2005
9
Patrons
8
Employees
Cases
7
6
Confirmed norovirus
5
4
3
2
1
05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
June
Norovirus Outbreak After Eating at
a Restaurant in Winona
• Environmental assessment:
– Inadequate employee illness logs
– Poor reporting of illness by employees
– Lack of management support to find and
exclude ill employees
– Washing lettuce in the handsink
How do we find out about
foodborne outbreaks in
Minnesota?
• Foodborne disease reporting and
investigation
• FoodNet
• Foodborne Illness Hotline
Reportable Foodborne Illnesses
• Campylobacteriosis*
•
• Cholera*
•
• Escherichia coli * infection •
(E. coli O157:H7 and other
•
pathogenic E. coli)
• Listeriosis*
• Salmonellosis*, including
typhoid
• Shigellosis*
• Yersiniosis*
* Submit isolates to MDH
Botulism
Cryptosporidiosis*
Giardiasis
Hemolytic uremic
syndrome
• Toxoplasmosis
Foodborne Disease Surveillance
in Minnesota
• FoodNet
• Active surveillance
– Laboratory audits
– Follow-up with health care providers
– Interview cases
Team Diarrhea and Vector Squad
March 2006
To order a copy of the 2005
Gastroenteritis Outbreak
Summary, go to:
www.health.state.mn.us
• Type “summary gastroenteritis” in the
search box.
• Complete the online order form.
• Hard copies will be mailed to you in a
couple of weeks.
Norovirus Outbreak
Example 3:
Sandwich Shop
Norovirus infection associated
with eating sandwiches
at a restaurant
• MDH was notified of illnesses in a group
of people after they ate a catered lunch
• MDH received numerous additional
independent illness complaints about
the same restaurant
Norovirus infection associated
with eating sandwiches
at a restaurant
• 39 persons interviewed
• 34 persons (87%) met the case definition
• 4 ill foodworkers were identified; one
additional foodworker had an ill family
member
• One patron and one ill foodworker tested
positive for norovirus
Norovirus infection associated
with eating sandwiches
at a restaurant
Controlling NoV
• MEANS PREVENTING TRANSFER OF VIRUS
• Handwashing
• Prohibiting bare-hand contact with RTE
food items
• Removing food workers with active
vomiting and/or diarrhea
• Restricting recently ill foodworkers (for 72
hours after symptoms subside)
• Sanitizing
No Bare-Hand Contact with
RTE Foods
• “Utensils” (i.e. gloves, papers,
tongs, etc)
• Education on proper use
• Choosing the proper utensil
• Glove integrity
• When to change/how to change
gloves
You can help prevent these
outbreaks!
• The key to implementing
a solid employee health
program is
communication.
• Talk to foodworkers
about the hazards of
vomiting and diarrhea.
• Work as a team to find
innovative ways to keep
ill foodworkers out of the
restaurant.
You can help prevent these
outbreaks!
• Inform foodworkers that they MUST report
GI symptoms to the PIC.
• Educate foodworkers about the need to:
– Report GI symptoms to the PIC
– Comply with strict handwashing requirements
– Comply with the no-bare hand contact requirements
• Use teachable moments to communicate
key facts about handwashing, illness,
foodsafety
Questions?