Norovirus study slide show presentation

1. Norovirus Outbreak in a Long Term Care Facility: A Retrospective Epidemiological Study Gillian Jones MBA MPH, PIDr. Tae LeeDr. Jason Brinkley UMC-IRB # 09-0250 1

2. Topics Study Objective Introduction Study Methods Study Results Control and Prevention References 2

3. Study Objective OBJECTIVE: Perform descriptive epidemiology of Norovirus (NV) in a nursing home outbreak and examine patient risk factors in transmission of Norovirus caused gastroenteritis. 3

4. Introduction NOROVIRUS Basic Epidemiology Agent – Norovirus, or Norwalk-like virus, classified as calciviruses, thought to be the most common causal agents of NONBACTERIAL gastroenteritis outbreaks. Reservoir – Humans only known reservoir Transmission Modes - probably by fecal-oral route, although in hospital setting contact or airborne transmission from vomitus and fomites. Also community food borne, waterborne and shellfish transmission Season – common name winter vomiting disease , stomach flu, viral diarrhea Geography – worldwide and common 4

5. Intro Cont’d-Clinical Manifestations Incubation Period – usually 24-48 hrs, but ranges from 10-50 hours Period of Communicability- during acute stage and up to 48 hours after diarrhea stops Characteristic Symptoms- N/V, diarrhea, abdominal pain, myalgia, h/a, malaise, low grade fever, or a combination Communicability – 48 hrs after last diarrhea, but viral shedding can occur from 7 days up to 2 weeks and infection risks unknown. Notorious Outbreak - The first recorded epidemic attributed to Norwalk virus occurred in an elementary school in Norwalk, Ohio, in 1968. 5

7. Infants, young children, and persons who are unable to care for themselves, such as the disabled or elderly, are at risk for dehydration from loss of fluids.

8. Immune compromised persons are at risk for dehydration because they may get a more serious illness, with greater vomiting or diarrhea.

10. 8

11. Host Risk Factors Demographics – Very Young under 5yo or very old over 65 yo Nutritional status if compromised Immune Status if compromised Other- close quarters such as cruise ships, camps, acute and long term care settings 9

12. Study Methods Epidemiological data and lab results collected in post-outbreak observational study Setting 150 bed nursing home facility in eastern North Carolina. Case status, symptom characteristics and potential risk factors identified using Medical-record review, 24-hour reports of change of condition and patient quarterly assessment. Financial and staff related data identified through key informant interview. De-identified data used in analysis. 10

13. Data entered into Excel 2007 and Powerpoint 2007 for exhibits Data entered into GOATv2.1 (general outbreak analysis tool) used by NCPH Regional Surveillance Team Six with Epi Info v3.5.1 Data entered into PASW 17.0 for frequencies Data entered into JMP univariate analysis, correlations, exhibits 11 Methods cont’d

14. RESULTS: Anoutbreak duration of 15 days with 2.2 median days illness affected 97 patients (66%) and 24 staff (15%) with symptoms of acute gastroenteritis. 71 patients met case definition, 49.6% patient-case attack rate. Ten patients required in house oral and IV rehydration, six patients required hospital evaluation, and one patient with co-morbidities died. A source case was identified. No association between food or water consumption and symptoms was identified after environmental testing of water, ice and food service. A NV strain in the Genogroup type II was identified. Residents were at higher risk of infection if they were physically dependent on staff care with a dependency score lower than ten {RR} of 1.22 95 %CI (range 0.60-2.47) or had an ill roommate {RR} of 1.23 95% CI (range 0.86-1.78). 12 Results- OVERVIEW

15. The average patient who became ill was an African American or Caucasian female with mean age of 83 years old; residents without illness were 7.5 years younger (mean age 75.5, p=0.06) There were no significant differences in race associated with increased risk of infection (59% African American) but there was in gender. Sixty - four patient-cases (89% of the infected cases) were female and seven patient-cases (13%) were male patient-cases at the facility. Sixty six percent (66%) of all the women in the retrospective cohort meeting case definitions were infected compared with thirty two percent (32%) of the men. Female RR=1.20 (95% CI 1.99 -1.43, p = 0.03). 13 Results- PERSON

16. FACILITY FLOORPLAN Both nursing units and all six wards had patients exhibiting acute gastroenteritis (AGE) symptoms Four of the six wards also had confirmed NV lab specimens (see Figure 1 NV lab confirmed case-patient rooms indicated with red dots). 14 Results-PLACE

17. Time Outbreak duration of 15 days 2.2 median days illness (range .5 -8 days) 15 Results- Day 8 NV lab confirmed, Enhanced Measures begun & LHD Notified Day 5 Clinical outbreak protocol begins Day 8 Ban on admissions & transfers begins Day 1 Index Case Report Day 8 LHD & SHD Notified Day 13 Last New Onset

18. Table 1 SYMPTOMS OF CASE-PATIENTS OF A LONG-TERM–CARE FACILITY DURING A NOROVIRUS OUTBREAK FROM DECEMBER 29, 2008 TO JANUARY 13, 2009* _____________________________________________________________________________ Characteristic CASE-Patient n/N (%) ________________________________________________________________________ Female 67/126 (87% of cohort ) Age 83 yo (range 53 to 105 years) Peak illness onset dates January 6, 2009 Illness Duration 15 days (Dec 29’08-Jan 13,’09) Median duration of illness in days 2.2 days (range 0.5- 9 days) †Median no. Co-Morbidities 1.8 (range 0-4) Symptom Diarrhea 67/71 (94 % of ill) Median number of stools in a 24 period 3.5 (range 2-6) Median days duration of diarrhea 2.1 (range1-5) Nausea 8/71 (10.4% of Ill) Vomiting 53/71 (68.8% of Ill) Abdominal cramps 1/71 (1% of Ill) Low Temp 31/71 (40.2% of Ill) Maximum Temp 100.5 F Headache & Myalgia 1/71 (1% of Ill) 16 Results- Symptoms

19. Risk Factor Symptomatic no Symptoms RR CI Range P/Test ________________________________________________________________________ Female 63 40 1.19 95(1.99 -1.43) P 0.03* Male 8 14 0.453 95 (0.19 -0.96) P 0.03* Caucasian 30 16 1.426 95(0.87-2.33) P 0.15 Sick Roommate 40 24 1.23 95(0.85-1.78) P 0.24 <3 days ill 39 54 1.82 95(1.47-2.25) P<.0001* >1 day ill 60 54 1.18 95(1.07-1.31) P 0.0025* Lived on M ward 6 14 0.32 95(0.134-0.792) P 0.0083* ADL<10score Dependency 16 10 1.217 95(0.60-2.46) P 0.584 17 Results- Risk Factors

20. Preventive Measures Preventive measures: Frequently wash your hands, especially after toilet visits and changing diapers and before eating or preparing food. Carefully wash fruits and vegetables, and steam oysters before eating them. Thoroughly clean and disinfect contaminated surfaces immediately after an episode of illness by using a bleach-based household cleaner. Immediately remove and wash clothing or linens that may be contaminated with virus after an episode of illness (use hot water and soap). Flush or discard any vomitus and/or stool in the toilet and make sure that the surrounding area is kept clean. Persons who are infected with Norovirus should not prepare food while they have symptoms and for 3 days after they recover from their illness Use hygiene measure applicable to diseases transmitted via fecal-oral route and respiratory hygiene if vomitus prevalent due to airborne droplets 18

21. Control Measures Surveillance: Report to local health authority: obligatory report of epidemics in some countries, no individual case report required. Surveillance of Norovirus Infection in the United States CDC currently does not conduct active surveillance to monitor outbreaks of gastroenteritis caused by noroviruses. Outbreaks are reported to CDC's Viral Gastroenteritis Section, Respiratory and Gastroenteric Viruses Branch, Division of Viral Diseases, National Center for Immunization and Respiratory Diseases (NCIRD) when states send specimens for testing or sequencing, or outbreaks are reported directly by states to the electronic database (eFORS) maintained by the Foodborne Diarrheal Diseases Branch. For further details please email calicinet@cdc.gov Confirmations: Lab stool and serum cultures- Virus may be identified in stools through RT-PCR reverse transcription polymerase chain reaction and antigen assays. In addition, several epidemiologic criteria have been proposed for use in determining whether an outbreak of gastroenteritis is of viral origin. Kaplan's criteria for this purpose are as follows: 1) a mean (or median) illness duration of 12 to 60 hours, 2) a mean (or median) incubation period of 24 to 48 hours, 3) more than 50% of people with vomiting, and 4) no bacterial agent previously found. Although quite specific, these criteria are not very sensitive, and therefore the possibility of a viral etiology should not be discarded if the criteria are not met. Precautions: control patient, contacts and the immediate environment Isolation of cases – Enteric precautions,-No quarantine Disease specific treatment-Fluid and electrolyte replacement in severe cases. In children aged less than five, give 10 mg elemental zinc per day for 10-14 days. Products like pedialyte and gatorade used 19

22. Future Directions in the USA Challenges: In addition to fecal/oral spread, Norovirus disease can spread via droplets from vomitus (person to person transmission) . So facilities must focus on methods to limit transmission including isolation precautions (e.g., cohort sick patients in a healthcare facility) and environmental disinfection.Noroviruses are highly resistant to standard sanitation measures. They are able to survive freezing, temperatures as high as 60°C, and have even been associated with illness after being steamed in shellfish. Moreover, noroviruses can survive in up to 10 ppm chlorine, well in excess of levels routinely present in public water systems. Epidemic measures: Search for vehicles of transmission and source but don’t wait for lab confirmations, need to implement control measures immediately. Disaster implications: Large-scale outbreaks could be a potential problem if water supplies or food preparation below hygiene standards. 20

24. Multi disciplinary enhanced hygiene measures limited outbreak to fifteen days.

27. http://www.cdc.gov/ncidod/dvrd/revb/gastro/norovirus-factsheet.htm

28. Heijne JC, Teunis P, Morroy G, et al. Enhanced hygiene measures and norovirus transmission during an outbreak. Emerg Infect Dis. 2009;15(1):24-30.

29. Norwalk-Like Viruses:' Public Health Consequences and Outbreak Management," MMWR, June 01, 2001 / 50(RR09);1-18

30. Marx A, Shay DK, Noel JS, et al. Outbreak of acute gastroenteritis in a geriatric long-term-care facility: combined application of epidemiological and molecular diagnostic methods. Infect Cont Hosp Epidemiol 1999;20:306--11.

31. Jiang X, Turf E, Hu J, et al. Outbreaks of gastroenteritis in elderly nursing homes and retirement facilities associated with human caliciviruses. J Med Virol 1996;50:335--41.