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Influenza, 2009

Influenza, 2009. Danae Bixler, MD, MPH Division of Infectious Disease Epidemiology. Objectives. Summarize 2009 respiratory outbreaks in West Virginia Review recently released information on novel influenza A (H1N1) Epidemiology Outbreaks Hospitalizations

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Influenza, 2009

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  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

  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 …

  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

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

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

  7. H1N1 Descriptive EpidemiologyEuro Surveill, 2009: 14(22):pii=19232

  8. Pediatric Hospitalization, ArgentinaNEJM, 2010, 362:45

  9. Pediatric Hospitalization, ArgentinaNEJM, 2010, 362:45

  10. Household TransmissionNEJM, 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.

  11. Household TransmissionNEJM, 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

  12. Household TransmissionNEJM, 2009, 361:2628

  13. 2009 Influenza A (H1N1) West Virginia Experience

  14. 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

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  21. 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

  22. 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

  23. 2009 Influenza A (H1N1) Outbreaks in the Current Literature

  24. Outbreak in a New York City High SchoolNEJM, 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

  25. MethodsNEJM, 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

  26. 119 confirmed cases • 2 hospitalized with LOS = 1 day NEJM, 2009 361:2628

  27. 124 laboratory-confirmed cases • 105 (85%) reported ILI • 5 (4%) laboratory-confirmed cases without ILI NEJM, 2009 361:2628

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

  29. 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 and/or environmental studies 11. Implement control and prevention measures 12. Initiate or maintain surveillance 13. Communicate findings

  30. Influenza A 2009 (H1N1) in Nursing HomesMMWR, 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

  31. Influenza Prevention and Control Guidelines for Nursing Homes MMWR, 2010; 59:74-77. • 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. • Instruct all residents and staff members to use respiratory hygiene and cough etiquette. • Restrict ill visitors and ill health-care personnel from the facility. • Continue active surveillance and use influenza testing for new cases of acute respiratory illness and influenza-like illness. • To the extent possible, segregate ill residents from unaffected residents and maintain appropriate levels of isolation. • When influenza is detected in the facility, administer influenza antiviral treatmentto 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. Lancet2000;355:93--7.

  32. Langiappe Group A Streptococcal Pharyngitis

  33. 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

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

  35. 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.

  36. Line List

  37. 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 and/or environmental studies 11. Implement control and prevention measures 12. Initiate or maintain surveillance 13. Communicate findings

  38. Conclusions • We survived … (the 1st 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

  39. 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

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