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COMMUNICABLE DISEASE MANUAL POLICIES / PROCEDURES
NOROVIRUS OUTBREAKS
OBJECTIVE:
Control and management of Norovirus.
DESCRIPTION:
Norovirus (genus Norovirus, family Caliciviridae) are a group of related, single
strand RNA, non-enveloped viruses that cause acute gastroenteritis in humans.
Norovirus is the approved official name for the group of viruses described as
"Norwalk-like viruses". Everyone is susceptible to norovirus infection and for
most individuals, it is a self-limiting illness. However, for the very young, the
elderly, and the immunosuppressed, the illness can be serious due to the risk
of dehydration. Immunity may be strain-specific and lasts for only a few
months. Given the genetic variability and continual mutation of noroviruses,
individuals are likely to be repeatedly infected throughout their lifetimes.
The incubation period for norovirus-associated gastroenteritis is between 24
and 48 hours (median in outbreaks 33 to 36 hours), but cases can occur within
12 hours of exposure. Primary symptoms include nausea, vomiting, and
watery, non-bloody diarrhea with abdominal cramps. Some individuals will also
have a low-grade fever, chills, headache, muscle aches, and general fatigue or
malaise. Onset of symptoms is very sudden. The symptoms last 24 to 60
hours. Recovery is usually complete without serious long-term effects.
Asymptomatic infection may occur in up to 30% of cases, and the virus can
shed in the stool for up to two (2) weeks after symptoms cease. If 50% of the
ill individuals report sudden acute vomiting, norovirus should be considered as
a possible cause of the outbreak.
Noroviruses are highly contagious, and it is thought that an inoculum of as few
as ten (10) viral particles is sufficient to infect an individual. During outbreaks
of noroviruses, several modes of transmission have been documented. For
example, initial consumption or handling of food prepared by ill food handler in
a restaurant, followed by secondary person-to-person transmission to
household contacts.
Norovirus is transmitted through the fecal-oral route. Norovirus is found in the
stool and vomit of infected individuals. Infection occurs primarily in one of three
ways:
swallowing food/water contaminated by norovirus; touching
contaminated surfaces and placing hands/fingers in the mouth; and breathing
in and swallowing airborne particles from the vomit and stool of infected
individuals. Norovirus is highly infectious, and outbreaks can occur in group
settings where there is close contact between individuals (i.e. schools, nursing
homes, day care centers, assisted living communities, cruise ships) and in
places/events where there is a common food and/or water source (i.e.
restaurants, banquets, wedding receptions, parties, catered meals, etc.).
Outbreaks have also been associated with consumption of cold foods, including
salads, sandwiches, and bakery products. Liquid items (e.g. salad dressings,
cake icing, and barbecue sauce) that allow the virus to mix evenly have often
been the cause of outbreaks. Food can be contaminated at its source (e.g.
oysters from contaminated waters, frozen raspberries and salads packaged for
widespread distribution by ill handler). Waterborne outbreaks have occurred in
community settings from sewage-contaminated wells and recreational waters.
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EQUIPMENT:
MDSS User Manual and disease specific form MDSS as Norovirus. The
Norovirus MDSS form is for lab results only. In place of Unusual Occurrence or
Outbreak Form, use Initial Cluster Form attached with policy, as not in MDSS.
Other forms needed are: Form A-Food Related Alert/Compliant Record, Form
B – Michigan Gastrointestinal Illness Complaint Review Form and the
Foodborne Illness Electronic Log. Faxes to Michigan Department of Community
Health (MDCH) and Michigan Department of Agriculture (MDA). The Initial
Cluster Form may also be used in place of the MDCH Notification of Serious
Communicable Disease Fax to MDCH. Fax numbers for MDCH and MDA are
listed
under
PROCEDURE.
Also
MDCH
web
site
at
www.michigan.gov/mdch, www.michigan.gov/cdinfo and CDC web site
at www.cdc.gov/diseasesconditions/az/a.html.
POLICY:
Legal Responsibility: Michigan's communicable disease rules of Act No. 368 of
the Public Acts of 1978, as amended, being 333.5111 of the Michigan
Compiled Laws. Notify MDCH and MDA immediately via phone and fax if
suspect or confirmed outbreak and follow-up within 24 hours post
referral.
PROCEDURE:
A.
Case Investigation
1.
Referral received per phone call, email, laboratory results, or
automatically through MDSS.
Document all case investigation proceedings.
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2.
Contact MD and/or client to start process of investigation within
24 hours of receiving referral.
3.
a.
Complete Form A, "Food Related Alert/Complaint
Record.
b.
Obtain menu with exactly what people ate and drank,
time and date of ingestion, location, etc. (See #5 for
specifics.)
c.
Complete Form B, "Case History: Clinical Data" for
several people with 72 hour food history.
d.
If case investigation reveals possible outbreak (defined
as two or more unrelated persons of different
households with similar symptoms, same pathogen, and
there is a time, person, and place association between
these persons), Notify the CD Supervisor, Medical
Director, and EH Supervisor for confirmed or
suspected cases. Call MDCH at 517-335-8165 and
Regional Epidemiologist. Nurse to Fax Notification
of Serious Communicable Disease Form to MDCH at
517-335-8263 for confirmed or suspected cases.
Form A and B needs to be faxed to MDA at 517-3733333 by the nurse.
e.
If outbreak, collect stool and food specimens – see
Criteria for Diagnosis – D of this policy.
4.
B.
f.
Enter into Foodborne Illness Electronic Complaint Log,
the date, time, and initial report of foodborne illness.
g.
The Laboratory will enter their positive results on MDSS
form called Norovirus for each person tested. We do not
have to fill out whole form in MDSS. For positive lab
results mark completed and confirmed, and for negative
results mark “not a case” – completed.
h.
For Food Management and Personnel exclusion see E.
Coli Policy.
If a confirmed outbreak, assistance will be sought from the
Regional Epidemiologist to develop a disease specific
questionnaire from information obtained from Form B, menu of
listed food items, including all condiments (dressings, barbecue
sauce, mustard, catsup, hot sauce, salad dressing, mayonnaise,
fruit and vegetable dips), all beverages, ice, water, dessert,
whipped or cream toppings, raw fruit and vegetable trays, types
of salads, rolls, breads, etc.
Case Definition
1.
Clinical Case Definition:





Diarrhea AND Vomiting OR
Three or more loose stools in 24 hours OR
Three or more vomiting episodes in 24 hours OR
Diarrhea with two additional symptoms OR
Vomiting with two additional symptoms
Additional Symptoms:







2.
Case Definition:



C.
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Low-grade fever (usually less than 101º F)
Myalgia (muscle aches)
Malaise (fatigue)
Abdominal cramping/pain
Headache
Nausea
Chill
Confirmed Case: The case is laboratory confirmed (whether
or not the individual is symptomatic).
Probable Case: The clinical case definition is met, but the
case has not been lab confirmed.
Suspect Case: The individual has not been interviewed, but
is reported to have symptoms similar to those which define a
clinical case.
Criteria for Diagnosis
1.
Fecal (Stool) Specimen Testing:





2.
Need to determine if infection is being caused by a bacterial
pathogen or a norovirus.
Testing for bacterial pathogens (i.e. Salmonella, Shigella,
Campylobacter, E. coli) can be done by a local lab or by the
Michigan Department of Community Health (MDCH) lab in
Lansing.
Testing for norovirus is performed at the Kalamazoo
Regional Lab or the MDCH lab and must be coordinated
through
the
State
Epidemiologist
(517-335-8165),
Kalamazoo Regional Lab (269-373-5360), MDCH lab (517335-8067) and the Van Buren Cass District County Health
Departmeny. Testing is only done in the event of an
outbreak situation, not for individual diagnosis. See MDCH
Norovirus Testing Requirements.
For norovirus testing, three (3) to six (6) individuals must
provide stool specimens, which will be sent as a batch to
either Kalamazoo Regional Lab or MDCH lab. Call MDCH
lab or Kalamazoo Regional Lab before sending specimens
and let them know when and how many specimens are
coming (e.g. one (1) or two (2) Styrofoam containers of eight
(8) stool specimens).
Remember, Enteric (bacterial
pathogens) must be sent in Enteric (Cary-Blair) Media
(#0551) with separate form DCH-0583. Collect Norovirus
samples in sterile plastic container without preservative or
Cary Blair.
Remember, you must call Bureau of Epidemiology at
517-335-8165 to obtain testing approval prior to sending
samples to either Kalamazoo Regional Lab or MDCH lab.
The Kalamazoo Regional Lab requisition may be used
for enteric specimens but not Norovirus. For Norovirus
use only MDCH Lab requisitions.
You must use
separate lab requisitions for enteric and Norovirus
testing; cannot use the same one.
Criteria for Laboratory Diagnosis:
Norovirus infection is confirmed by reverse transcription
polymerase chain reaction (RT-PCR) analysis (done at MDCH)
of the stool.
Again, this testing is done for outbreak
investigations only.
D.
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Control Measures
1.
WASH YOUR HANDS! Wash hands frequently with soap and
water, especially after using the bathroom or changing diapers
and before eating or preparing food. Alcohol-based hand gels
can also be used for effective hand hygiene.
2.
Infected food handlers MUST NOT prepare or serve food for
others under any circumstances. Furthermore, it is strongly
recommended that food preparation by infected individuals be
restricted for a period of two weeks after symptoms cease. They
can be given different duties in the restaurant such as working
the cash register or hostessing during this time.
E.
F.
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3.
Infected individuals should be isolated from group dining and
other activities while symptomatic and for 24 to 48 hours after
symptoms cease. Because the virus can shed in the stool for up
to two weeks, these individuals must pay special attention to
hand washing and should avoid preparing/serving food for
others during this time.
4.
Staff that interact (e.g. provide care, deliver meals, etc.) with sick
and well patients need to wash hands thoroughly between visits
and consider visiting well rooms first.
5.
It is strongly recommended that symptomatic staff members be
sent home and not return to work for a period of 24 to 48 hours
after their symptoms cease.
6.
Properly dispose of vomit and feces (stool) in a toilet. Wear a
face mask if one is available to avoid inhaling and swallowing
infectious aerosolized viral particles. Keep surrounding areas
clean and sanitize with a bleach-based household cleaner.
7.
Thoroughly clean and disinfect any contaminated surfaces with a
bleach-based cleaner immediately following an illness episode.
Again, wear a face mask if one is available to avoid infection.
8.
Remove and wash all potentially contaminated clothing and
bedding with soap and hot water immediately following an illness
episode.
9.
Remove bowls/jars of snacks and unwrapped candy from
common areas since they are easily contaminated.
10.
In several instances, contaminated water has been documented
as the source of a norovirus outbreak. If a shared water supply
is implicated as a possible source of the outbreak, all water for
drinking and for food preparation should be boiled before use or
use bottled water.
11.
See MDCH Guidelines
Disinfection of Norovirus.
for
Environmental
Cleaning
and
Refer to appropriate Fact Sheet for Education of Case and Contacts
1.
Public Health Nursing (PHN) will notify cases of lab results and
document notification on index card.
2.
PHN will use appropriate fact sheet for education and teaching.
3.
PHN will complete Outbreak specific folder (e.g. Palisades
Outbreak 2004).
MDSS Case Reporting:
REFERENCES:
1.
Complete case investigation using Initial Cluster Report and
MDSS Norovirus lab results as described above.
2.
Notify CD Supervisor that the case report is ready for review.
PHN will be notified if corrections are needed prior to closing
case in MDSS.
3.
CD Supervisor reviews case for completeness and closes MDSS
case report and will copy MDSS Form and file in specifically
named “Outbreak” file.
MMWR, June 1, 2001, Vol. 50, No. 9
Current Red Book
Current Control of Communicable Diseases Manual
Current disease specific “Fact Sheet”
Websites: www.cdc.gov/diseasesconditions/az/a.html
www.michigan.gov/cdinfo
www.michigan.gov/mdch/norovirus
Norovirus: Instruction for Fecal (Stool)
Specimen Collection - PATIENT
1.
Collect stool specimen as soon as possible.
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2.
How to collect the stool specimen:
a.
The stool should be passed directly into a clean, dry container that can be discarded after
use (e.g. clean and dry margarine tub, milk carton with the lid cut off, wide-mouth jar or
paper plate placed into toilet).
CAUTION:
 DO NOT pass the stool directly into the specimen container.
 DO NOT urinate on the feces
 DO NOT pass the feces into the toilet.
3.
Put on the gloves and use the wooden tongue blades to put the stool into the dry specimen
container and close the lid tightly. (Use tape around the lid edges to prevent leaks.) The container
should be approximately one-third (1/3) full (1.0 oz. [2-3 tablespoons] is the minimal volume
needed).
4.
WASH HANDS THOROUGHLY! An infective dose is 10-100 viral particles and there are
approximately 1 MILLION viruses in one (1) gram of stool.
5.
Write the date and time collected on the specimen bottle and lab requisition form.
6.
Place specimen bottle in 4"x9" clear plastic sleeve wrapped in the folded paper towel.
7.
Fasten folded, completed lab requisition around plastic wrapped bottle with rubber band.
8.
Place the above ensemble into the 4½"x9" clear plastic bag (wider one).
9.
Place in paper bag and bring to Berrien County Health Department (BCHD) at 769 Pipestone Street,
Benton Harbor. If unable to bring specimen right away, keep cold, but not in refrigerator that
contains food. Place on an ice pack in a plastic bag in a cool place until the specimen can be
taken to the health department. PLEASE DO NOT FREEZE THE SPECIMEN.
Norovirus: Instruction for Fecal (Stool)
Specimen Collection - NURSING
1. Use sterile orange cap tube containing no preservative.
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2. Contact people selected for stool specimen collection to come to health department to pick up
containers or deliver to location convenient for them.
Nurse prepares stool specimen:
a.
Complete MDCH Microbiology/Virology Test Requisition #DCH-0583 for both
Kalamazoo Regional Lab and MDCH lab (copy attached). Need phone, fax number,
and contact name for results. Make sure requisition stamped (Nursing, Berrien
County Health Department with address). Also include:
 Patient's last name, first name and middle initial.
 County of residence
 Gender
 Race/Ancestry
 Social Security number
 Date of birth
 Onset date of symptoms
 Date collected (instruct patient to complete)
 Time collected (instruct patient to complete)
 Fill in stool for specimen source
 Fill in Suspected Outbreak, specify Food Outbreak #2951.
 Complete Outbreak Identifier - Name of Outbreak
 Complete Organism Suspected - #2951.
b.
Label bottle with patient’s name and date of birth; write date collected and time
collected on a white file folder label and place on bottle. Instruct patient to complete
date and time collected after placing stool in container.
 Place small biohazard sticker on lid of specimen container.
 Wrap labeled bottle with folded paper towel.
 Place towel wrapped bottle into 4” x 9” clear plastic bag.
 Fold completed MDCH requisition #DCH-0583 and wrap around bagged, toweled,
specimen bottle.
 Wrap rubber band around requisition and bottle.
 Place the above ensemble into a 4½” x 9” clear plastic bag.
 Place labeled tube with two (2) rubber gloves and two (2) tongue blades into a small
paper bag with patient’s name on it.
c.
Instruct patient how to obtain stool specimen using Patient Instruction Sheet.
 Go through how specimen wrapped and collected.
 Reminder: must write date and time collected on lab requisition and on specimen
bottle and tape lid shut on bottle to avoid leakage.


Complete missing information on lab requisition form with patient present.
Instruct to bring specimen back to health department double bagged in paper bag.
d.
Returned specimens are checked by nursing for completeness of both specimen bottle and
requisition – WEAR GLOVES!
e.
Place double bag specimens in a Styrofoam container with lid (Viral #46 size) located over
sink in Exam Room #5, Benton Harbor.
f.
Place in bottom of lab refrigerator while waiting for rest of specimens to arrive so can batch
send to MDCH lab.
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g.
Contact MDCH lab at (517)-335-8067 or Kalamazoo Regional Lab at (269) 373-5360 or
(269) 373-5359, when sending specimens (e.g. two (2) Styrofoam containers containing
eight (8) stool specimens). Contact State Epidemiologist at (517)-335-8165 to advise
sending such and such number of specimens and to which lab sending.
h.
To send specimens:
 Only send Monday, Tuesday, or Wednesday.
 Put on gloves and remove double bagged specimens with attached lab requisitions.
 Place in #46 size Styrofoam box with frozen ice pack (will hold 3 to 4 specimens).
 Stamp Diagnostic Label with MDCH lab or Kalamazoo Regional Lab address with
Nursing – Berrien County Health Department return address and place in Styrofoam box.
 Tape Styrofoam box shut.
 Place at switchboard for postage label and mailing.
Norovirus: Control Measures for Public
1.
WASH YOUR HANDS! Wash hands frequently with soap and water, especially after using
the bathroom or changing diapers and before eating or preparing food. Alcohol-based hand
gels can also be used for effective hand hygiene.
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2.
Infected food handlers MUST NOT prepare or serve food for others under any circumstances.
Furthermore, it is strongly recommended that food preparation by infected individuals be
restricted for a period of two weeks after symptoms cease. They can be given different duties
in the restaurant such as working the cash register or hostessing during this time.
3.
Infected individuals should be isolated from group dining and other activities while
symptomatic and for 24 to 48 hours after symptoms cease. Because the virus can shed in the
stool for up to two weeks, these individuals must pay special attention to hand washing and
should avoid preparing/serving food for others during this time.
4.
Staff that interact (e.g. provide care, deliver meals, etc.) with sick and well patients need to
wash hands thoroughly between visits and consider visiting well rooms first.
5.
It is strongly recommended that symptomatic staff members be sent home and not return to
work for a period of 24 to 48 hours after their symptoms cease.
6.
Properly dispose of vomit and feces (stool) in a toilet. Wear a face mask if one is available to
avoid inhaling and swallowing infectious aerosolized viral particles. Keep surrounding areas
clean and sanitize with a bleach-based household cleaner.
7.
Thoroughly clean and disinfect any contaminated surfaces with a bleach-based cleaner
immediately following an illness episode. Again, wear a facemask if one is available to avoid
infection.
8.
Remove and wash all potentially contaminated clothing and bedding with soap and hot water
immediately following an illness episode.
9.
Remove bowls/jars of snacks and unwrapped candy from common areas since they are easily
contaminated.
10.
In several instances, contaminated water has been documented as the source of a norovirus
outbreak. If a shared water supply is implicated as a possible source of the outbreak, all
water for drinking and for food preparation should be boiled before use or use bottled water.
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