1. Marion County Public Health Department
Noroviruses
Marion County
Public Health Department

2. What are noroviruses?
Group of viruses that cause the “stomach flu,” or gastroenteritis
The term norovirus was recently approved as the official name for this group of viruses.
Approximately 23 million cases each year in U.S.
Leading cause of outbreaks of gastroenteritis
Winter vomiting disease
Norovirus used to be called Norwalk virus.
It is now thought that at least 50% of all food borne outbreaks of gastroenteritis can be attributed to noroviruses.

3. Symptoms Nausea, vomiting, diarrhea, abdominal cramps
Sometimes low-grade fever, chills, headache, myalgia, fatigue
Often begins suddenly, and the infected person may feel very sick
Norovirus infection usually presents as acute-onset of vomiting, watery non-bloody diarrhea with abdominal cramps, and nausea.
Vomiting is more common in children.

4. Incubation, Duration, Communicability
Incubation period: hours (median in outbreaks is hours)
Duration of illness: hours
Period of communicability: onset through 72 hours after recovery
Presymptomatic viral shedding may occur.
Shedding usually begins with onset of symptoms and may continue for 2 weeks after recovery. It is unclear to what extent viral shedding over 72 hours after recovery plays into transmission of the disease.

5. Transmission Found in the stool and vomit of infected people
Infective dose as few as 100 viral particles
Can be transmitted several ways:
Eating food or drinking liquids that are contaminated with norovirus
Direct person-to-person spread
Airborne and fomite transmission in droplets contaminating surfaces or entering the mouth and being swallowed
Environmental and fomite contamination may also act as a source of infection. Good evidence exists for transmission due to aerosolization of vomitus that presumably results in droplets contaminating surfaces or entering the oral mucosa and being swallowed. No evidence suggests that infection occurs through the respiratory system.
Ill people may spread the disease for as long as a week after symptoms leave

6. How serious is it?
Usually not serious, although people may feel very sick and vomit many times a day
Most get better within 1 or 2 days, and they have no long-term health effects related to their illness
Can be serious for the very young, the elderly, and persons with weakened immune systems due to dehydration

7. Treatment Drink plenty of fluids to prevent dehydration
No antiviral medication
No vaccine to prevent infection
Cannot be treated with antibiotics because antibiotics work to fight bacteria and not viruses
By drinking oral rehydration fluids, juice or water people can reduce their chance of becoming dehydrated. Sports drinks do not replace the nutrients and minerals lost during this illness.

8. Immunity
Limited immunity, may be strain specific and last only a few months
Can recur throughout a person’s lifetime
Some people are more likely to become infected and develop more severe illness than others
Example: people with O blood group most susceptible
In a study conducted at the NCRR-supported General Clinical Research Center (GCRC) at the University of North Carolina at Chapel Hill, Dr. Christine L. Moe and her colleagues found that more than half of 77 volunteers exposed to Norwalk virus, a type of norovirus, were resistant to infection. About half of these protected individuals had FUT2 mutations that blocked production of H type-1, a carbohydrate and blood group antigen found on many cell surfaces. All volunteers who had two copies of the nonfunctional FUT2 gene remained healthy, even after receiving high doses of the virus. The findings suggest that H type-1 is the cellular receptor that binds Norwalk virus and allows it to enter cells. The study also jibes with earlier clinical studies that identified possible links between blood group antigens and norovirus susceptibility.

9. Critical Characteristics
Highly contagious
Multiple modes of transmission
Stable in the environment
Resistant to routine disinfection methods
Asymptomatic infections
Limited immunity
Noroviruses are relatively resistant to environmental challenge: they are able to survive freezing, temperatures as high as 140 degrees F, and have even been associated with illness after being steamed in shellfish. Moreover, noroviruses can survive in up to 10ppm chlorine, well in excess of levels routinely present in public water systems.
Oregon Health Division said that norovirus probably survive on a surface for at least a few days, perhaps several weeks depending on variables such as temperature, UV irradiation, perhaps humidity, etc.
Asymptomatic infection may occur in as many as 30% of infections, although the role of asymptomatic infection in norovirus transmission in not well understood.

10. Definition of a Gastroenteritis Outbreak
An outbreak is a higher number of ill cases above baseline
2-3 ill cases with vomiting or diarrhea at a facility maybe a signal that an outbreak is starting
Facilities are required by law to report any suspected outbreak of disease and are permitted to provide information on illnesses per HIPAA
OAR to HIPPA information.

11. Hand Washing After using restrooms and before eating
Before and after direct contact with residents
Hand wash sinks have warm water, soap, and paper towels
Alcohol-based hand sanitizer to supplement hand washing
Hand washing is preferred. Alcohol-based hand sanitizer is not a substitute for hand washing, and should only be used when hands are not visibly soiled.
Alcohol-based sanitizer is effective against similar viruses. Resource MMWR 2002 Hand Washing.

12. Hand washing is the single most important practice to prevent the spread of outbreaks!
HANDS MUST BE WASHED:
Whenever they are visibly soiled or there has been contact with stool.
Between contact with different residents.
Before putting on gloves and after removing gloves.
After using the toilet.
Before eating or smoking.
Before handling or preparing food.
A PROPER HAND WASH INCLUDES:
Using warm running water and soap with plenty of friction for 20 seconds.
Using a clean paper towel to dry your hands and to turn off the tap.
Use of a waterless hand sanitizer may be substituted for hand washing only if adequate sink facilities are not immediately accessible and hands are not visibly soiled.

13. General Staff Guidelines
Educate regular and agency staff about infection control practice
Eliminate floating staff from affected to unaffected areas
Notify supervisor immediately if ill
Furlough ill staff for 72 hours after symptoms resolve
Ill food service workers and servers should not prepare or handle food
Non-essential staff should not be allowed on the floor during an outbreak
Be careful when using agency staff, may want to screen for gastroenteritis before entering the facility.

14. General Staff Guidelines
Wear gloves, gowns, and mask during contact with ill residents
Pairing employees who have recovered from the illness with currently ill residents
Exclude non-essential personnel
When ill staff return to work, cohort them with ill residents.
Some people may be contagious for up to two weeks after recovery. Continue good hand washing.
The kitchen staff should avoid passing trays on an affected floor.

15. Residents and Visitors
Recommend no new admissions
Confine ill residents to rooms until 72 hours after symptoms resolve
Place ill resident on contact precautions
Cancel group activities (dining room)
Do not transfer residents from affected areas to unaffected areas
Post signs to inform visitors of outbreak
Do not allow children to visit

16. What can happen if the dining room is not closed?
The graph below shows how allowing common dining during an outbreak can exponentially increase the spread of illness. On Days 1 and 2, a resident (a different resident on each day) vomited while in the common dining area. Approximately 30 hours later, residents sitting around the ill persons became ill (day 4 and 5). Closing the common dining area can help avoid this dramatic increase in the number of cases in your facility.

18. General Cleaning Principles
Wear disposable gloves, gowns, and mask when cleaning up vomit or diarrhea
Clean soiled areas with detergent and hot water first
Always clean with paper towels or disposable cloths and dispose in infectious waste bags.
Disinfect with freshly-made (daily) bleach solution of 1/2 cup of 6% household bleach to one gallon of water

19. Cleaning Specific Things
Increase routine cleaning
Contaminated hard surfaces: soak up excess liquid with paper towels, thoroughly clean with hot water and detergent, and disinfect with a bleach solution
Contaminated carpets: soak up excess liquid with paper towels, clean with hot water and detergent, then disinfect with bleach solution (if bleach-resistant) or steam clean

20. Cleaning Specific Things
Frequently clean hand contact surfaces, e.g. door handles, railings, tabletops, etc. with bleach solution

21. Virkon Disinfectant
Potassium peroxymonosulfate and Sodium chloride (equivalent to 9.75% available chlorine)
Currently available Wilco Farm Stores
Check Marion County Health website:
1% solution of Virkon is recommended for disinfection of hard non-porous surfaces. Let stand for 10 minutes. Cleans and disinfects in one step, after removing gross dirt. Not for use on acid-sensitive surfaces such as marble and soft metals such as copper, brass, and certain grades of aluminum. Three year shelf life and a 1% solution is stable for 7 days.
Purchased from American Safe Room’s, Oakland, OR or Wilco Farm Stores.

22. Laundry Staff
Wear disposable gloves, gowns, and mask when handling contaminated laundry
Maintain separate bins for dirty and clean laundry
Place contaminated laundry in impermeable bags for transportation to laundry room
Do not hose off fecal material from soiled laundry, this can aerosol the norovirus.

23. Kitchen Staff
Furlough ill staff for 72 hours after symptoms resolve. After returning to work, restrict from handling kitchenware and ready-to-eat food for another 72 hours
Double hand wash after using restroom, eating, breaks
Use single-use gloves in addition to hand washing
Limit access of bin-style ice machine to kitchen staff
Keep food covered when transporting
Discard any food handled by an infected worker
Disinfect food prep areas with bleach solution
Environmental Health often recommends a chlorine/water hand dip at all food service hand sinks during an outbreak. Mix a 50 to 100ppm chlorine bleach and water, dip hands into chlorine solution after washing hands in sink.
Approximately 50% of all norovirus outbreaks are linked to ill food-service workers.

24. Vomiting Incidents in the Kitchen
Carefully remove all visible vomit.
Disinfect food preparation area with ½ cup of bleach to one gallon of water.
Discard exposed food or single-serve articles within a 25-foot radius of the incident.
Food contact surface disinfection should be followed with a clear-water rinse and a final wipe down of 1 tablespoon of bleach to one gallon of water.
In norovirus outbreak, a vomiting incident is a major risk factor for norovirus illness and can double the attack rate. See MMWR November 23,2007 page 1216

25. Dining Post signs encouraging hand washing before eating
Discontinue self-service salad bars, family style dining, communal fruit bowls
Provide alcohol-based hand sanitizer to supplement hand washing

26. Public Restrooms Discourage use when possible
Clean frequently using a freshly made bleach solution of 1/2 cup of 6% household bleach to one gallon of water
Bleach

27. Gastroenteritis Outbreaks in Marion County for 2006

28. Gastroenteritis Outbreaks in Marion County 2007

29. Gastroenteritis Outbreaks in Marion County 2008

31. Marion County Health Department Follow Up
Collecting data on Gastroenteritis Case Log until Norovirus is identified
Collecting stool samples
Putting control measures into place for staff, residents, volunteers, and visitors
Site visit by Environmental Health
Working with Oregon Health Division
Daily monitoring of outbreak

32. Only enter resident who meet the case definition. Rule out bowel care, chronic diarrhea, new medications pregnancies, etc.
Addition information and forms on MCHD website:

33. Collecting Stool Specimens
5-6 stools from ill or recently ill resident and staff.
Collect stool specimen, the size of a walnut in a clean container with a lid.
Label container with name, dob, and date collected.
Refrigerate until specimen can be brought in to the health department.
Viral antigens or RNA are detectable in stool for as long as a week after symptoms resolve. ---DHS Norwalk-like virus guidelines

34. Outbreak Declared Over
Seven days must pass without new cases before an outbreak of Norovirus-like gastroenteritis is
declared over
Outbreak is declared over when two incubation cycles have been completed.

35. Partnership with other agencies
Reinforcing the same control measures
Building continuity of care
Promoting communication between the health department and other agencies

36. Sources
                                                                                                                                                                                                                                                                                                                                                                                                                                                
Robert E. Wheeler, MD, FACEP. Voyager Medical Seminars