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