1. Understanding Norovirus
PHN ITV
October 17, 2013
T.J. Sugg, MPH

2. Objectives
Describe the epidemiology and clinical features of norovirus (NoV).
Discuss LHD and KDPH response to NoV outbreaks
Discuss surveillance strategies for NoV
Describe NoV prevention and control measures
Describe a NoV outbreak that occurred in KY
Describe the emergence of the GII.4 Sydney NoV

3. Epidemiology and Clinical Features

4. Norovirus Single-stranded RNA virus Calciviridae family Also known as:
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 viruses
Stomach flu / 24-hour flu (misnomers – not influenza)
Winter time vomiting disease

5. Genetic Classification of NoV

6. 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

7. NoV Incidence

8. Clinical Disease Incubation period: 12-48 hours
Acute onset vomiting and/or diarrhea
Watery, non-bloody stools
Abdominal cramps, nausea, low-grade fever
Most recover after hours
10-12% seek medical attention; some require hospitalization and fluid therapy
Severe 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

9. Viral Shedding Primarily in stool, but also in vomitus
Occurs for at least 2-3 weeks
Peaks 4 days after exposure
1010 viral copies/gram of feces
May persist after symptoms resolve
Infectious dose: 18 to 1,000 viral particles
A droplet of vomitus has enough viral particles to infect over 100,000 people
NoV can survive 12 hours on a surface, 12 days in contaminated fabric. A study demonstrated survival for 61 days in well water.

10. Transmission Person to person Food Recreational and Drinking Water
Direct fecal-oral
Ingestion of aerosolized vomitus
Indirect via fomites or contaminated environment
Food
Contaminated by infected food handlers
Point of service or source (e.g., raspberries, oysters, leafy vegetables)
Recreational and Drinking Water
Well contamination from septic tank
Chlorination system breakdown
In healthcare, most likely from direct contact with
infected persons or contaminated equipment

11. Transmission Cycle

12. Laboratory Confirmation
RT-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:

13. Immunity Short-term immunity after infection
Little cross protective immunity
No long-term immunity
Protection believed to be less than a year. Some studies suggest only a few months
Genetic susceptibility
Some may be resistant to NoV infection
No commercially available test to identify those who might carry genes conferring resistance to NoV infection

14. Vaccine Intranasal vaccine Safe and immunogenic
47% effective against NoV gastroenteritis
Bivalent GI.1/GII.4 vaccine currently being tested in human volunteers

15. Surveillance

16. National Outbreak Reporting System (NORS)
Comprehensive national surveillance system for all US outbreaks
Launched in February 2009
Helps to assess the national burden and temporal trends of outbreaks
Aids in identifying priority settings and population for interventions
Assists in characterizing outbreaks
Pathogen
Setting
Mode of transmission

17. Calcinet Molecular NoV genotyping network (Similar to PulseNet)
Data shared between public health labs and CDC
Links outbreaks and identifies common sources
Identifies emergent variants
Implemented March 2009

18. 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

19. LHD Quick Reference Guide for NoV Outbreaks

20. Reporting
Jasie 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.

21. Reporting Continued
Outbreaks 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.

22. LHD Quick Reference Guide for NoV Outbreaks
Notify KDPH RDS of potential outbreak
Establish a working case definition
The three 3’s
3 days per incubation period
Up to 3 days exclusion for employees after symptoms have resolved
At least 3 positive specimens to confirm outbreak
Encourage and review proper hand washing

23. LHD Quick Reference Guide for NoV Outbreaks
Cleaning and disinfecting surfaces:
Particular attention to high-touch surfaces
Clean, then disinfect surfaces
Use 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

24. LHD Quick Reference Guide for NoV Outbreaks
Recommend 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 possible
Contacts of symptomatic patients should be monitored for symptoms

25. LHD Quick Reference Guide for NoV Outbreaks
Recommend the facility have signs on all entrances about the outbreak
Cancel or postpone group activities
Recommend 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)

26. LHD Quick Reference Guide for NoV Outbreaks
When 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 hours
A mean (or median) incubation period of hours
More than 50% of people with vomiting, and
No bacterial agent found

27. Prevention and Control

28. Where hands go…go Noro Practice 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

29. Food Preparation
Wash fruits and vegetables before preparing and eating them
Cook oysters and other shellfish thoroughly before eating them
Food that might be contaminated with NoV should be thrown out
Keep sick infants and children out of areas where food is being handled and prepared
When sick, do not prepare food or care for others for at least 72 hours after symptoms subside

30. Environmental Control
Clean 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 thoroughly
Immediately remove and wash clothes or linens that may be contaminated with vomit or stool
Handle soiled items carefully without agitating them
Wear rubber disposable gloves and wash hands afterward
Wash items with detergent at the maximum available cycle length then machine dry them

31. Controlling NoV in Food Service
Handwashing
Prohibiting bare-hand contact with ready-to-eat (RTE) food items
Removing food service workers with active vomiting and/or diarrhea
Restricting recently ill food service workers for 72 hours after symptoms subside
Sanitizing

32. No Bare-Hand Contact with RTE Foods
Use of utensils (i.e., gloves, papers, tongs, etc.)
Educate workers on proper use
Choosing the proper utensil
Glove integrity
When to change/how to change gloves

33. Employee Health Program
Communication is a key element
Educate food service workers on hazards of vomiting and diarrhea
Work as a team to find innovate ways to keep ill food service workers out of the restaurant
Inform food service workers that they must report GI symptoms to the person in charge
Report GI symptoms
Comply with strict handwashing requirements
Comply with no-bare hand contact requirement
Use teachable moments

35. KY NoV Outbreak at a Youth Basketball Tournament

36. Background February 3-5, 2012 7th grade boys basketball tournament
Lexington, KY
Statewide tournament
52 schools
>600 players

37. Methods Identify cases Standard case report form
Basketball coaches
Absentee data from schools
Employees
Standard case report form
Illness history
Food and water exposures
Stool samples required for testing

38. Case Definitions Probable case Confirmed case
Vomiting or diarrhea in a tournament attendee
Onset within 72 hours of attendance
No laboratory confirmation of norovirus
Confirmed case
Probable case with stool specimen positive for norovirus by real-time reverse transcription-polymerase chain reaction (RT-qPCR)

39. Basketball Teams

40. Identified Cases

41. Results No common food or water exposure
6 (100%) stool specimens tested positive for norovirus
Genogroup II type 7 (GII.7)
Confirmed cases were from 4 different teams

42. Cases of Acute Gastroenteritis, by Data of Onset
Tournament Dates

43. Cases of Acute Gastroenteritis, by Data of Onset
Tournament Dates

44. Cases of Acute Gastroenteritis, by Data of Onset
Tournament Dates
Vomiting
Episode

45. Cases of Acute Gastroenteritis, by Data of Onset
Tournament Dates
Vomiting
Episode

46. Conclusions
NoV caused an outbreak of acute gastroenteritis at a basketball tournament in KY
Person-to-person transmission
Public vomiting episode
Contaminated environmental surfaces

47. Public Health Recommendations
Exclusion of players with gastroenteritis symptoms within 24 hours
Increased education on personal hygiene
Clean and disinfect environmental surfaces

48. Emergence of GII.4 Sydney Norovirus, United States, 2012-2013

49. GII.4 Sydney New NoV strain identified in March 2012
Caused acute gastroenteritis outbreaks in New Zealand, Japan, Western Europe, Canada, and the United States
Became the predominant NoV strain implicated in outbreaks

50. GII.4 Sydney Incidence
From 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 compared to 18 weeks in and 22 weeks in

51. GII.4 Sydney Transmission
Mode of transmission
Person to person (76.1 %)
Foodborne (15.5%)
Other/unknown (8.4%)
Setting
LTCF/hospital (75.2%)
School/childcare center (1.8%)
Restaurant/banquet facility (15.5%)
Other/multiple settings (6.2%)
Unknown (1.3%)

52. GII.4 Sydney
Has become the predominant strain of circulating NoV in the US
Replaced the previously predominant GII.4 New Orleans strain
Does not appear to have caused a substantial increase in the level of outbreak or endemic NoV disease activity compared with the previous 2 seasons

53. Resources

55. In Summary

56. In Summary

57. In Summary

58. Thank you!!

59. Questions?
Contact information: T.J. Sugg, MPH Reportable Diseases Section Infectious Disease Branch KY Department for Public Health x4244