Presentation on theme: "Marion County Public Health Department"— Presentation transcript:
1Marion County Public Health Department NorovirusesMarion CountyPublic Health Department
2What are noroviruses?Group of viruses that cause the “stomach flu,” or gastroenteritisThe 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 gastroenteritisWinter vomiting diseaseNorovirus 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.
3Symptoms Nausea, vomiting, diarrhea, abdominal cramps Sometimes low-grade fever, chills, headache, myalgia, fatigueOften begins suddenly, and the infected person may feel very sickNorovirus infection usually presents as acute-onset of vomiting, watery non-bloody diarrhea with abdominal cramps, and nausea.Vomiting is more common in children.
4Incubation, Duration, Communicability Incubation period: hours (median in outbreaks is hours)Duration of illness: hoursPeriod of communicability: onset through 72 hours after recoveryPresymptomatic 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.
5Transmission Found in the stool and vomit of infected people Infective dose as few as 100 viral particlesCan be transmitted several ways:Eating food or drinking liquids that are contaminated with norovirusDirect person-to-person spreadAirborne and fomite transmission in droplets contaminating surfaces or entering the mouth and being swallowedEnvironmental 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
6How serious is it?Usually not serious, although people may feel very sick and vomit many times a dayMost get better within 1 or 2 days, and they have no long-term health effects related to their illnessCan be serious for the very young, the elderly, and persons with weakened immune systems due to dehydration
7Treatment Drink plenty of fluids to prevent dehydration No antiviral medicationNo vaccine to prevent infectionCannot be treated with antibiotics because antibiotics work to fight bacteria and not virusesBy 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.
8ImmunityLimited immunity, may be strain specific and last only a few monthsCan recur throughout a person’s lifetimeSome people are more likely to become infected and develop more severe illness than othersExample: people with O blood group most susceptibleIn 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.
9Critical Characteristics Highly contagiousMultiple modes of transmissionStable in the environmentResistant to routine disinfection methodsAsymptomatic infectionsLimited immunityNoroviruses 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.
10Definition of a Gastroenteritis Outbreak An outbreak is a higher number of ill cases above baseline2-3 ill cases with vomiting or diarrhea at a facility maybe a signal that an outbreak is startingFacilities are required by law to report any suspected outbreak of disease and are permitted to provide information on illnesses per HIPAAOAR to HIPPA information.
11Hand Washing After using restrooms and before eating Before and after direct contact with residentsHand wash sinks have warm water, soap, and paper towelsAlcohol-based hand sanitizer to supplement hand washingHand 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.
12Hand 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.
13General Staff Guidelines Educate regular and agency staff about infection control practiceEliminate floating staff from affected to unaffected areasNotify supervisor immediately if illFurlough ill staff for 72 hours after symptoms resolveIll food service workers and servers should not prepare or handle foodNon-essential staff should not be allowed on the floor during an outbreakBe careful when using agency staff, may want to screen for gastroenteritis before entering the facility.
14General Staff Guidelines Wear gloves, gowns, and mask during contact with ill residentsPairing employees who have recovered from the illness with currently ill residentsExclude non-essential personnelWhen 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.
15Residents and Visitors Recommend no new admissionsConfine ill residents to rooms until 72 hours after symptoms resolvePlace ill resident on contact precautionsCancel group activities (dining room)Do not transfer residents from affected areas to unaffected areasPost signs to inform visitors of outbreakDo not allow children to visit
16What 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.
18General Cleaning Principles Wear disposable gloves, gowns, and mask when cleaning up vomit or diarrheaClean soiled areas with detergent and hot water firstAlways 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
19Cleaning Specific Things Increase routine cleaningContaminated hard surfaces: soak up excess liquid with paper towels, thoroughly clean with hot water and detergent, and disinfect with a bleach solutionContaminated 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
20Cleaning Specific Things Frequently clean hand contact surfaces, e.g. door handles, railings, tabletops, etc. with bleach solution
21Virkon DisinfectantPotassium peroxymonosulfate and Sodium chloride (equivalent to 9.75% available chlorine)Currently available Wilco Farm StoresCheck 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.
22Laundry StaffWear disposable gloves, gowns, and mask when handling contaminated laundryMaintain separate bins for dirty and clean laundryPlace contaminated laundry in impermeable bags for transportation to laundry roomDo not hose off fecal material from soiled laundry, this can aerosol the norovirus.
23Kitchen StaffFurlough ill staff for 72 hours after symptoms resolve. After returning to work, restrict from handling kitchenware and ready-to-eat food for another 72 hoursDouble hand wash after using restroom, eating, breaksUse single-use gloves in addition to hand washingLimit access of bin-style ice machine to kitchen staffKeep food covered when transportingDiscard any food handled by an infected workerDisinfect food prep areas with bleach solutionEnvironmental 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.
24Vomiting 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
25Dining Post signs encouraging hand washing before eating Discontinue self-service salad bars, family style dining, communal fruit bowlsProvide alcohol-based hand sanitizer to supplement hand washing
26Public 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 waterBleach
27Gastroenteritis Outbreaks in Marion County for 2006
31Marion County Health Department Follow Up Collecting data on Gastroenteritis Case Log until Norovirus is identifiedCollecting stool samplesPutting control measures into place for staff, residents, volunteers, and visitorsSite visit by Environmental HealthWorking with Oregon Health DivisionDaily monitoring of outbreak
32Only enter resident who meet the case definition. Rule out bowel care, chronic diarrhea, new medications pregnancies, etc.Addition information and forms on MCHD website:
33Collecting 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
34Outbreak Declared Over Seven days must pass without new cases before an outbreak of Norovirus-like gastroenteritis isdeclared overOutbreak is declared over when two incubation cycles have been completed.
35Partnership with other agencies Reinforcing the same control measuresBuilding continuity of carePromoting communication between the health department and other agencies
36SourcesRobert E. Wheeler, MD, FACEP. Voyager Medical Seminars