1. Influenza, 2009 Danae Bixler, MD, MPH Division of Infectious Disease Epidemiology

2. Objectives Summarize 2009 respiratory outbreaks in West Virginia Review recently released information on novel influenza A (H1N1) – Epidemiology – Outbreaks – Hospitalizations Review an outbreak of Streptococcal pharyngitis 2

3. Respiratory Outbreaks, 2009 (provisional) 53 outbreaks reported by 31 (56%) counties – 25 (47%) 2009 influenza A (H1N1) – 9 (17%) Influenza-like illness – 5 (9%) Influenza A – 5 (9%) Upper respiratory illness – 3 (6%) Group A Streptococcus – 2 (4%) Influenza B – 4 other … 3

4. 2009 Influenza A (H1N1) April 24, 2009 MMWR – 2 human cases of swine-origin influenza in Southern California No history of swine contact ILI in family contacts May 1, 2009 MMWR – Cases in California, Texas Not linked to each other Not linked to outbreak in Mexico 4

5. 2009 Influenza A (H1N1) NEJM, 2009; 361:115 5

6. H1N1 Descriptive Epidemiology Euro Surveill, 2009: 14(22):pii=19232 6

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8. Pediatric Hospitalization, Argentina NEJM, 2010, 362:45 8

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10. Household Transmission NEJM, 2009, 361:2628 May 28, 2009: 938 probable/confirmed H1N1 case reports – 533 (57%) households had two to six members 216 (41%) households without missing information – 600 household contacts. Acute respiratory illness = 2 or more of: – Fever – Cough – Sore throat or – Runny nose Secondary cases occurred within 7 days. 10

11. Household Transmission NEJM, 2009, 361:2628 Transmission of Acute Respiratory Illness in Households Median age in households = 26 years Median age of secondary cases = 16.5 years AR = 28% in households with 2 members AR = 9% in houssholds with 6 members 11

12. Household Transmission NEJM, 2009, 361:2628 VariableEstimated Odds Ratio (95% CI) P Value Age of household contact 0-4 years3.52 (1.55 – 7.97)0.003 5-18 years2.01 (1.11 – 3.63)0.03 19-50 years1.00 > 51 years0.41 (0.08 – 2.04)0.28 Doubling of household size0.27 (0.14 – 0.52)<0.001 12

13. WEST VIRGINIA EXPERIENCE 2009 Influenza A (H1N1) 13

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18. Approach to Influenza Outbreak Investigation 1. Prepare for field work 2. Establish the existence of an outbreak 3. Verify the diagnosis 4. Construct a working case definition 5. Find cases systematically and record information 6. Perform descriptive epidemiology 7. Develop hypotheses 8. Evaluate hypotheses epidemiologically 9. As necessary, reconsider, refine, and re-evaluate hypotheses 10. Compare and reconcile with laboratory and/or environmental studies 11. Implement control and prevention measures 12. Initiate or maintain surveillance 13. Communicate findings 18

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26. General Measures for Congregate Settings with Healthy Individuals… (CDC) Keep / send ill persons home Encourage – Respiratory etiquette – Hand hygiene Routine environmental cleaning Leave policies – Don’t require MD note – Don’t reward perfect attendance Educate persons with underlying conditions 26

27. Control of Influenza in Long Term Care Pre-season immunization of patients and staff Isolation of ill persons Secure the diagnosis rapidly – 8-10 specimens from recently ill persons Begin antiviral prophlaxis according to recommendations Continued surveillance to assess impact of control measures 27

28. OUTBREAKS IN THE CURRENT LITERATURE 2009 Influenza A (H1N1) 28

29. Outbreak in a New York City High School NEJM, 2009 361:2628 Thursday, April 23, 2009 – 100 of 2686 high school students ill – Fever, headache, dizziness, sore throat, respiratory symptoms Friday, April 24, 2009: health department team dispatched – NP and OP specimens – School event for April 24 cancelled Sunday, April 26: CDC confirmed H1N1 April 25-May 3: School closed 29

30. Methods NEJM, 2009 361:2628 NP swabs for RT-PCR On-line survey of students – Recruitment by mass e-mail – Phone contact for persons with worsening illness Case = fever + cough or sore throat 30

31. 119 confirmed cases 2 hospitalized with LOS = 1 day NEJM, 2009 361:2628 31

32. 124 laboratory-confirmed cases 105 (85%) reported ILI 5 (4%) laboratory-confirmed cases without ILI NEJM, 2009 361:2628 32

33. Epidemiology NEJM, 2009 361:2628 Incubation PeriodDuration of Illness 33 5% developed symptoms by 0.9 days 50% by 1.4 days 95% by 2.2 days Summary: incubation period = 1-2 days 50% recovered by 6 days 75% recovered by 9 days Summary: recovery takes as much as 1-2 weeks

34. NYC Schools Influenza Outbreak Investigation 1. Prepare for field work 2. Establish the existence of an outbreak 3. Verify the diagnosis 4. Construct a working case definition 5. Find cases systematically and record information 6. Perform descriptive epidemiology 7. Develop hypotheses 8. Evaluate hypotheses epidemiologically 9. As necessary, reconsider, refine, and re-evaluate hypotheses 10. Compare and reconcile with laboratory studies 10. Compare and reconcile with laboratory and/or environmental studies 11. Implement control and prevention measures 12. Initiate or maintain surveillance 13. Communicate findings 34

35. Influenza A 2009 (H1N1) in Nursing Homes MMWR, 2010; 59:74-77. 3 nursing home outbreaks: – ILI attack rates: Residents: 6% - 28% Staff: 5% - 40% – Control Oseltamivir prophylaxis Droplet precautions Hand hygiene and cough etiquette Restrict new admissions and visitors 35

36. Influenza Prevention and Control Guidelines for Nursing Homes MMWR, 2010; 59:74-77. Vaccinate Vaccinate health-care personnel against seasonal influenza and 2009 pandemic influenza A (H1N1). Vaccinate residents of long-term--care facilities for seasonal influenza and offer 2009 H1N1 as this vaccine becomes widely available. respiratory hygiene cough etiquette Instruct all residents and staff members to use respiratory hygiene and cough etiquette. Restrict ill visitors and ill health-care personnel Restrict ill visitors and ill health-care personnel from the facility. Continue active surveillance and use influenza testing Continue active surveillance and use influenza testing for new cases of acute respiratory illness and influenza-like illness. segregate ill residents appropriate levels of isolation To the extent possible, segregate ill residents from unaffected residents and maintain appropriate levels of isolation. administer influenza antiviral treatment and influenza antiviral prophylaxis When influenza is detected in the facility, administer influenza antiviral treatment to ill residents and influenza antiviral prophylaxis to unaffected residents. Unaffected health-care personnel should be offered influenza antiviral prophylaxis. SOURCES: CDC. Interim guidance on infection control measures for 2009 H1N1 influenza in healthcare settings, including protection of healthcare personnel; October 14, 2009. Available at http://www.cdc.gov/h1n1flu/guidelines_infection_control.htm. Carman WF, Elder AG, Wallace LA, et al. Effects of influenza vaccination of health-care workers on mortality of elderly people in long-term care: a randomised controlled trial. Lancet 2000;355:93--7. http://www.cdc.gov/h1n1flu/guidelines_infection_control.htm 36

37. GROUP A STREPTOCOCCAL PHARYNGITIS Langiappe 37

38. GAS Pharyngitis Acute pharyngotonsillitis – Fever – Sore throat Complications – Scarlet fever – Rheumatic fever – Acute glomerulonephritis – Purulent complications: otitis media, sinusitis, peritonsillar and retropharyngeal abcesses, suppurative cervical adenitis 38

39. GAS Pharyngitis Transmission: – Person-to-person – Foodborne – No fomite or zoonotic transmission Colonization – 15% of asymptomatic children – Persist for months – Transmission is minimal 39

40. GAS pharyngitis diagnosis Who should be tested? – Acute onset – Fever – Clinical signs and symptoms or exposure Pharyngeal exudate Pain on swallowing Enlarged tender anterior cervical nodes Do not test children with viral syndrome: – Coryza, conjunctivitis, hoarseness, cough, etc. 40

41. Line List GradeFever Sore Throat Rapid Positive Culture PositiveStudent/Staff Diagnosis Date KyyyyStudent5/1/2009 KyyyStudent5/1/2009 1yyyStudent5/1/2009 KyyyyStudent5/3/2009 KyyyStudent5/3/2009 3yyyStudent5/4/2009 3yyyyStudent5/4/2009 KyyyStudent5/4/2009 1yyyStudent5/4/2009 yyyStaff5/4/2009 yyyStaff5/4/2009 41

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43. GAS Pharyngitis Outbreak Investigation 1. Prepare for field work 2. Establish the existence of an outbreak 3. Verify the diagnosis 4. Construct a working case definition 5. Find cases systematically and record information 6. Perform descriptive epidemiology 7. Develop hypotheses 8. Evaluate hypotheses epidemiologically 9. As necessary, reconsider, refine, and re-evaluate hypotheses 10. Compare and reconcile with laboratory studies 10. Compare and reconcile with laboratory and/or environmental studies 11. Implement control and prevention measures 12. Initiate or maintain surveillance 13. Communicate findings 43

44. Conclusions We survived … (the 1 st wave). Experience with seasonal influenza surveillance / outbreak investigation was an excellent model for pandemic response Outbreak investigation is good practice for the next public health emergency 44

45. For most basic outbreaks: 2. Establish the existence of an outbreak 3. Verify the diagnosis 11. Implement control and prevention measures 12. Initiate or maintain surveillance 13. Communicate findings 45