Post on 31-Jan-2016
description
Understanding Norovirus
PHN ITV
October 17, 2013
T.J. Sugg, MPH
ObjectivesDescribe the epidemiology and clinical
features of norovirus (NoV).Discuss LHD and KDPH response to NoV
outbreaksDiscuss surveillance strategies for NoVDescribe NoV prevention and control
measuresDescribe a NoV outbreak that occurred in KYDescribe the emergence of the GII.4 Sydney
NoV
NorovirusSingle-stranded RNA virusCalciviridae family
Two human genera: noroviruses and sapoviruses
Six genogroups (I through VI) I, II, and IV affect humans 35 genotypes Hundreds of different strains
Also known as:Norwalk-like virusesStomach flu / 24-hour flu
(misnomers – not influenza)Winter time vomiting disease
Genetic Classification of NoV
NoV Disease Burden in the United States
Annual Estimate Lifetime Risk
Deaths 800 1 in ~5,000
Hospitalizations 71,000 1 in ~50
Emergency Department Visits
414,000 1 in ~9
Outpatient Visits 1.7 million 1 in ~2
Cases 21 million 5.6
NoV Incidence
Clinical DiseaseIncubation period: 12-48 hoursAcute onset vomiting and/or diarrhea
Watery, non-bloody stoolsAbdominal cramps, nausea, low-grade fever
Most recover after 12-72 hours10-12% seek medical attention; some require
hospitalization and fluid therapySevere disease occurs more frequently among older
adults, young children, and immunocompromised patients
More severe illness and death possible in elderly and those with other illnesses
30% of infections are asymptomatic
Viral SheddingPrimarily in stool, but also in vomitusOccurs for at least 2-3 weeksPeaks 4 days after exposure
1010 viral copies/gram of fecesMay persist after symptoms resolve
Infectious dose: 18 to 1,000 viral particlesA droplet of vomitus has enough viral particles to
infect over 100,000 peopleNoV can survive 12 hours on a surface, 12 days
in contaminated fabric. A study demonstrated survival for 61 days in well water.
TransmissionPerson to person
Direct fecal-oralIngestion of aerosolized vomitusIndirect via fomites or contaminated environment
FoodContaminated by infected food handlersPoint of service or source (e.g., raspberries, oysters,
leafy vegetables)Recreational and Drinking Water
Well contamination from septic tankChlorination system breakdown
In healthcare, most likely from direct contact with
infected persons or contaminated equipment
Transmission Cycle
Laboratory ConfirmationRT-PCR is preferred method for diagnosing NoV.
KDPH Division of Laboratory Services (DLS) has this capability.
During outbreaks, KDPH and DLS request only 7-10 specimens to confirm the existence of a NoV.
Stool specimens should be collected during acute phase of illness.
Vomitus may be submitted for testing, but stool is preferred
Packaging and shipping instructions available on DLS website: http://chfs.ky.gov/NR/rdonlyres/0C2947A7-D115-4846-B133-B565DFDEBA57/0/norovirus2013.pdf
ImmunityShort-term immunity after infectionLittle cross protective immunityNo long-term immunity
Protection believed to be less than a year. Some studies suggest only a few months
Genetic susceptibilitySome may be resistant to NoV infectionNo commercially available test to
identify those who might carry genes conferring resistance to NoV infection
VaccineIntranasal vaccineSafe and immunogenic47% effective against NoV gastroenteritisBivalent GI.1/GII.4 vaccine currently being
tested in human volunteers
National Outbreak Reporting System (NORS)Comprehensive national surveillance system for
all US outbreaksLaunched in February 2009Helps to assess the national burden and temporal
trends of outbreaksAids in identifying priority settings and
population for interventionsAssists in characterizing outbreaks
PathogenSettingMode of transmission
CalcinetMolecular NoV genotyping network (Similar
to PulseNet)Data shared between public health labs and
CDCLinks outbreaks and identifies common
sourcesIdentifies emergent variantsImplemented March 2009
NoV Sentinel Testing and Tracking (NoroSTAT)Select state health departments participate in
this network (MN, OH, OR, TN, WI)States report suspected NoV outbreaks
through NORS and CalciNet within 7 business days of notification of the outbreak to the health department.
Allows NoV strain data uploaded through CalciNet to be rapidly linked with epidemiologic characteristics of outbreaks reported through NORS
ReportingJasie Logsdon, MPH, MA is the foodborne and
waterborne disease epidemiologist and serves as the primary point of contact for NoV outbreak reporting.
KDPH is in the process of updating guidance for responding to NoV outbreaks in various settings within the community, including jails, schools, long-term care facilities (LTCF), assisted living facilities, and other healthcare or residential facilities, such as independent living facilities, residential care facilities for the developmentally disabled, acute care, transitional care, and rehabilitation units.
Reporting ContinuedOutbreaks of NoV should be reported to the
local health department within the jurisdiction in which the outbreak is occurring or KDPH immediately upon recognition of the outbreak.
LHD Quick Reference Guide for NoV OutbreaksNotify KDPH RDS of potential outbreakEstablish a working case definitionThe three 3’s
3 days per incubation periodUp to 3 days exclusion for employees after
symptoms have resolvedAt least 3 positive specimens to confirm
outbreakEncourage and review proper hand washing
LHD Quick Reference Guide for NoV OutbreaksCleaning and disinfecting surfaces:
Particular attention to high-touch surfacesClean, then disinfect surfacesUse a chlorine bleach solution (5.25%; 25
tablespoons bleach per gallon of water) for hard, nonporous surfaces or disinfectants registered as effective against NoV by EPA
Prepare fresh dilution of bleach every day and discard unused portions
LHD Quick Reference Guide for NoV OutbreaksRecommend that ill staff members in health-
care facilities and food handlers be excluded during acute illness and for 72 hours following resolution of symptoms
Recommend use of contact precautions (gown, gloves, and surgical mask)
Avoid cross-coverage of staff members between units or facilities with affected patients
Cohort symptomatic patients when possibleContacts of symptomatic patients should be
monitored for symptoms
LHD Quick Reference Guide for NoV OutbreaksRecommend the facility have signs on all
entrances about the outbreakCancel or postpone group activitiesRecommend that the facility close to new
admissions for 2 incubation periods (6 days) after the last onset of symptoms among residents and staff.
Collect stool specimens on 7 to 10 ill patients or staff. Contact KDPH RDS for coordination of testing with DLS.
Enter data into NORS (Regional Epidemiologists)
LHD Quick Reference Guide for NoV OutbreaksWhen transferring symptomatic patients, notify
EMS and the hospital or the receiving facility in advance
Conduct a site visit with environmentalist and/or obtain a diagram of the facility layout
Kaplan Criteria for outbreak determination if no specimens are available:A mean (or median) illness duration of 12-60 hoursA mean (or median) incubation period of 24-48 hoursMore than 50% of people with vomiting, andNo bacterial agent found
Where hands go…go NoroPractice proper hand hygiene
Wash hands with soap and water Especially after using the toilet and changing
diapers Always before eating, preparing, or handling food
Stay at home if you are ill
Food PreparationWash fruits and vegetables before preparing and
eating themCook oysters and other shellfish thoroughly
before eating them Food that might be contaminated with NoV
should be thrown outKeep sick infants and children out of areas
where food is being handled and preparedWhen sick, do not prepare food or care for
others for at least 72 hours after symptoms subside
Environmental ControlClean and disinfect contaminated surfaces
After vomiting or having diarrhea, immediately clean and disinfect contaminated surfaces.
If a sick individual has been in food preparation areas, all surfaces should be cleaned and disinfected.
Use a chlorine bleach solution (5-10% solution) or other disinfectant registered as effective against NoV by EPA
Wash laundry thoroughlyImmediately remove and wash clothes or linens that may
be contaminated with vomit or stoolHandle soiled items carefully without agitating themWear rubber disposable gloves and wash hands
afterwardWash items with detergent at the maximum available
cycle length then machine dry them
Controlling NoV in Food ServiceHandwashingProhibiting bare-hand contact with ready-to-
eat (RTE) food itemsRemoving food service workers with active
vomiting and/or diarrheaRestricting recently ill food service workers
for 72 hours after symptoms subsideSanitizing
No Bare-Hand Contact with RTE FoodsUse of utensils (i.e., gloves, papers, tongs,
etc.)Educate workers on proper use
Choosing the proper utensilGlove integrityWhen to change/how to change gloves
Employee Health ProgramCommunication is a key elementEducate food service workers on hazards of
vomiting and diarrheaWork as a team to find innovate ways to keep
ill food service workers out of the restaurantInform food service workers that they must
report GI symptoms to the person in chargeReport GI symptomsComply with strict handwashing requirementsComply with no-bare hand contact requirement
Use teachable moments
BackgroundFebruary 3-5, 20127th grade boys basketball tournamentLexington, KYStatewide tournament52 schools>600 players
MethodsIdentify cases
Basketball coachesAbsentee data from schoolsEmployees
Standard case report formIllness historyFood and water exposures
Stool samples required for testing
Case DefinitionsProbable case
Vomiting or diarrhea in a tournament attendeeOnset within 72 hours of attendanceNo laboratory confirmation of norovirus
Confirmed caseProbable case with stool specimen positive for
norovirus by real-time reverse transcription-polymerase chain reaction (RT-qPCR)
Basketball Teams
Identified Cases
ResultsNo common food or water exposure6 (100%) stool specimens tested positive for
norovirusGenogroup II type 7 (GII.7)Confirmed cases were from 4 different teams
Cases of Acute Gastroenteritis, by Data of Onset
Tournament Dates
Cases of Acute Gastroenteritis, by Data of Onset
Tournament Dates
Cases of Acute Gastroenteritis, by Data of Onset
Tournament Dates
Vomiting
Episode
Cases of Acute Gastroenteritis, by Data of Onset
Tournament Dates
Vomiting
Episode
ConclusionsNoV caused an outbreak of acute
gastroenteritis at a basketball tournament in KY
Person-to-person transmissionPublic vomiting episodeContaminated environmental surfaces
Public Health RecommendationsExclusion of players with gastroenteritis
symptoms within 24 hours Increased education on personal hygieneClean and disinfect environmental surfaces
GII.4 SydneyNew NoV strain identified in March 2012Caused acute gastroenteritis outbreaks in
New Zealand, Japan, Western Europe, Canada, and the United States
Became the predominant NoV strain implicated in outbreaks
GII.4 Sydney IncidenceFrom Aug 1, 2012 – April 16, 2013, 637 NoV
outbreaks were reported by MN, OH, OR, TN, and WI.
Cumulative number of outbreaks increased in 3 states (OR, TN, and OH) compared to the previous two seasons
Peak activity occurred in January 2013 and was 16% higher than the average peak month outbreak activity in the 2 preceding seasons
Season duration was 21 weeks in 2012-13 compared to 18 weeks in 2011-12 and 22 weeks in 2010-11
GII.4 Sydney TransmissionMode of transmission
Person to person (76.1 %)Foodborne (15.5%)Other/unknown (8.4%)
SettingLTCF/hospital (75.2%)School/childcare center (1.8%)Restaurant/banquet facility (15.5%)Other/multiple settings (6.2%)Unknown (1.3%)
GII.4 Sydney Has become the predominant strain of
circulating NoV in the USReplaced the previously predominant GII.4
New Orleans strainDoes not appear to have caused a substantial
increase in the level of outbreak or endemic NoV disease activity compared with the previous 2 seasons
http://www.cdc.gov/norovirus/about/index.html
In Summary
In Summary
In Summary
Thank you!!
Questions?Contact information:
T.J. Sugg, MPHReportable Diseases SectionInfectious Disease Branch
KY Department for Public Healthtennis.sugg@ky.gov
502.564.3261 x4244