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Management of Suspect Cases of Human Infection with Avian Influenza A (H5N1) Virus PowerPoint Presentation
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Management of Suspect Cases of Human Infection with Avian Influenza A (H5N1) Virus

Management of Suspect Cases of Human Infection with Avian Influenza A (H5N1) Virus

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Management of Suspect Cases of Human Infection with Avian Influenza A (H5N1) Virus

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  1. Management of Suspect Cases of Human Infection with Avian Influenza A (H5N1) Virus

  2. Outline • Part 1: • Background and epidemiology of avian influenza A (H5N1) virus infection in humans • Human H5N1 clusters • Clinical features of human infection with H5N1 virus • Part 2: • Assessing case patients: Collecting clinical and epidemiologic information • Specimen collection and diagnostics • Treatment

  3. Management of Suspect Cases of Human Infection with Avian Influenza A (H5N1) Virus Part 1: Epidemiology and Clinical Features 3

  4. Part 1: Learning Objectives • Understand the epidemiology of known human H5N1 cases and risk factors • Importance of clusters • Recognize clinical features of H5N1 in humans

  5. Epidemiology of H5N1 Virus Infection of Humans Photo: T. Uyeki, CDC

  6. Global Epidemiology • 385 cases have been reported to WHO from 15 countries* • Case fatality proportion = 243/385: ~ 63% • Human surveillance has focused upon severe respiratory disease (pneumonia) *Reported as of July 9, 2008

  7. Progression of Human Cases

  8. Human Avian Influenza A (H5N1) Cases by Onset Date and Country(as of 12 November 2007) As of 12 November 2007, total of 335 cases were reported officially to WHO * Cases missing onset date are excluded: 1 Viet Nam, 13 Indonesia, 3China, 3 Azerbaijan, 13 Egypt, 1 Turkey, 1 Iraq, 1 Nigeria ** CFR Trend: computed based on cumulative dead & total

  9. WHO Summary of H5N1 cases • Summary of H5N1 cases as of January, 2008* • Median age: 18 years (range 3 months - 75 years) • 90% of cases were aged <40 years • Male to female ratio = 1:1 • Median time to hospitalization: 4 days • Case fatality proportion: ~60% • Highest case fatality: 10-19 years (76%) • Lowest case fatality: ≥50 years (40%) • Median time to death: 9 days (range 2 – 31 days) *Writing Committee of the Second World Health Organization Consultation on Clinical Aspects of Human Infection with Avian Influenza A (H5N1) Virus NEJM 358 (3): 261,January 2008. WHO Weekly Epidemiological Record 2007;82:41-8

  10. Review Question #1 Which two countries have reported the most Influenza A (H5N1) cases to WHO to date? a. Indonesia and Vietnam b. Egypt and Thailand c. China and Cambodia d. India and China Answer: a. Indonesia and Vietnam

  11. Review Question #2 What age group has the highest reported case fatality rate from H5N1 virus infection? a. 0-9 years old b. 10-19 years old c. 20-29 years old d. > 50 years old Answer: 10 – 19 years old

  12. Risk Factors: Exposures in the Week Before Illness • Touching sick or dead poultry • Slaughtering, preparing for cooking • Touching dead wild birds • Having sick or dead poultry in the household • Visiting a live poultry market Photo: AP/ Bikas Das

  13. Risk Factors: Culture-Specific Risk • Eating uncooked duck blood • Defeathering of swans • Playing with dead chickens • Contact with roosters used in cock fighting Photo: TIME Magazine / John Stanmeyer

  14. Avian to Human Transmission of H5N1 • Primary mode of transmission is avian-to-human (zoonoses): • Exposure to infected poultry • Preparing or consuming uncooked or undercooked H5N1 virus-infected poultry or poultry products • Indirect transmission may occur through: • Inhalation of aerosolized H5N1 virus infected material • Contact with surfaces contaminated with infected poultry feces • Contact with infected animals that ate dead poultry

  15. Human-to-Human Transmission of H5N1 Virus Infection • Probable but limited, non-sustained* human-to-human transmission • Very rare, but documented • Occurred during close, prolonged, unprotected contact with a human H5N1 case • Mostly in family members • Hospital transmission reported *Currently, no evidence of sustained human-to-human H5N1 virus transmission

  16. Human H5N1 Case Clusters

  17. Occurrence of H5N1 Clusters • >25% of all cases have occurred in clusters • Clusters are 2 or more H5N1 cases that are epidemiologically-linked • Occurred in several countries • Hong Kong (2003) • Thailand (2004) • Indonesia (2006)

  18. Case Cluster, Hong Kong 2003 Family of five Hong Kong residents visited Fujian Province, southern China in late January 2003 7-year old girl developed pneumonia and died, was buried, but not tested Four survivors returned to Hong Kong Father and son were hospitalized with pneumonia; both confirmed with H5N1, father died No direct link between cases and avian flu infection in poultry was found

  19. Case Cluster, Thailand 2004 11-year old girl who lived in a rural village with her aunt where poultry deaths occurred Mother lived near Bangkok (no poultry exposure) The girl developed fever and lower respiratory tract disease, hospitalized with pneumonia Mother and aunt traveled to hospital to provide care The girl died 24 hours later Mother and aunt became sick, were confirmed with H5N1 virus infection; mother died Probable human-to-human transmission of H5N1 virus from girl to her mother and aunt

  20. Case Cluster, Indonesia 2006 A large H5N1 family cluster occurred in North Sumatra 1 probable + 7 confirmed H5N1 cases 7 deaths H5N1 virus was isolated from 7 cases Index case was likely infected by contact with sick/dead chickens Limited human-to-human-to-human transmission

  21. Interpretation of Case Clusters Cases with similar illness onset dates Same exposure source, similar incubation period? Cases with illness onset separated in time Similar exposure source, different incubation periods? Different exposure sources? Limited human-to-human transmission?

  22. Significance of Case Clusters Increase in number and size of clusters, or increase in number of mild cases can indicate: That H5N1 viruses are spreading to more people Possible increased adaptability of H5N1 viruses to humans Signal for: An increased pandemic threat and a change in WHO Pandemic Alert Period Phases The beginning of a pandemic Early containment ded

  23. Assessing for Possible Human-to- Human H5N1 Virus Transmission • Cases occur close together in time among individuals who had close contact with a human H5N1 case • Family members, close contacts, health care workers • One case has illness onset within one incubation period (within 7 days) after exposure to another H5N1 case • No other sources of exposures are found

  24. Assessing for Possible Human-to- Human H5N1 Virus Transmission • Documented exposure to a confirmed, probable, or suspected human H5N1 case, • AND • The time interval between contact with a suspected, probable, or confirmed H5N1 case and illness onset is 7 days or less, • AND • No other sources of H5N1 exposures • Such as: birds, other animals, feathers, droppings, fertilizers made of fresh bird droppings, live poultry markets, contaminated environments, or laboratory specimens

  25. H5N1 Cluster Summary • ~25% of confirmed H5N1 cases have occurred in clusters worldwide • Mostly among blood related family members • Most cluster cases had contact with sick birds • Evidence of limited, non-sustained, human-to-human contact has occurred • Clinically mild pediatric H5N1 cases identified during investigations of severely ill index cases • Changes in size, number or epidemiology of clusters could signal important viral changes/adaptability, or pandemic

  26. Review Question #3 If you recognize a cluster of human H5N1 cases, what would cause you to suspect that human-to-human transmission of H5N1 virus has occurred? Answer: Documented exposure to a confirmed, probable, or suspected human H5N1 case, AND The time interval between contact with a suspected, probable, or confirmed H5N1 case and illness onset is 7 days or less, AND No other sources of H5N1 exposures

  27. Clinical Features of Human Infection with H5N1 Virus

  28. H5N1 Viral Cycle in Humans • Incubation period • Generally from 2 to 7 days • Viral shedding period for H5N1 virus • Still largely unknown • May be 2 weeks or longer • Longer for children and immune compromised

  29. Clinical Manifestations • Common signs and symptoms: • Fever ≥38C, cough, shortness of breath, difficulty breathing • Other findings (less common): • Sore throat, headache, muscle aches, diarrhea • Clinical findings are non-specific, and are similar to other common acute respiratory diseases • Critical to ask about H5N1 exposures

  30. Complications of H5N1 Infection • Most common: pneumonia • Progresses to respiratory failure • Requires mechanical ventilation • Acute respiratory distress syndrome (ARDS) • Gastrointestinal disease • Multi-organ failure • Heart and kidney dysfunction • Neurologic symptoms • Encephalitis, seizures, altered mental status, progression to coma

  31. H5N1 Pathogenesis High H5N1 viral levels are associated with an abnormal inflammatory response Other blood changes Decreased white blood cell count Low lymphocyte count Mild to moderately decreased platelet count Infection and inflammation contribute to respiratory failure and multi-organ failure Cytokine dysregulation (cytokine “storm”) 31

  32. Part 1 Summary: Epidemiology • Most human H5N1 cases have been healthy children and young adults • Most H5N1 cases had direct contact with sick or dead poultry or birds in the week prior to illness onset • Limited, non-sustained human-to-human transmission of H5N1 virus is rare, but has occurred

  33. Part 1 Summary: Clinical Manifestation • Signs and symptoms of H5N1 infection are non-specific and are observed in other respiratory diseases: • Fever, cough, shortness of breath, difficulty breathing • Pneumonia • Peripheral blood changes

  34. Review Question #4 What clinical signs and symptoms are pathognomonic for Influenza A (H5N1) infection? Answer: None. Some signs and symptoms may more commonly occur with Influenza A(H5N1) infection than with complications of severe seasonal influenza A virus infections. However the symptoms are non-specific, and similar to other common acute respiratory diseases. This points to the critical importance of understanding all epidemiologic linkages to possible sources of exposure in order to raise the index of suspicion of possible H5N1 infection.

  35. Management of Suspect Cases of Human Infection with Avian Influenza A (H5N1) Virus Part 2: Diagnosis, Management, and Treatment

  36. Part 2: Overview • Assessing suspected patients: Collecting clinical and epidemiologic information • Diagnostic and laboratory tests • Current recommendations for clinical treatment

  37. Part 2: Learning Objectives • Identify important sources of clinical and epidemiologic information • Recognize laboratory tests used for identification of new cases • Clinical specimen collection, diagnostic and laboratory rests • Know the treatments and interventions for suspected case-patients and their contacts

  38. Part 2: Learning Objectives, cont • Know what pharmaceutical treatments are available for seasonal and pandemic influenza • Understand the difference in the recommendations between seasonal vs. pandemic flu treatment

  39. Assessing Suspected H5N1 Patients

  40. Assessing Suspected H5N1 Patients Does the patient have findings consistent with H5N1 virus infection? • Collect clinical history and data on clinical findings • Evaluate epidemiological data • Consider clinical, laboratory, and epidemiologic information together

  41. Clinical Data to Collect • Date of illness onset • Signs and symptoms • Routine laboratory results • Complications • Type and date of onset • Clinical specimens collected for H5N1 testing • Precautions used, breaks in precautions

  42. Clinical Data • Common signs and symptoms: • Fever • Cough • Shortness of breath • Difficulty breathing • Other signs and symptoms that may occur: • Sore throat • Sputum production (may be bloody) • Diarrhea / abdominal pain • Muscle aches • Headache • Runny nose

  43. Clinical Complications • Respiratory failure • Complication from pneumonia within a few days to 2 weeks after illness onset • Acute Respiratory Distress Syndrome • Multiple organ failure • Renal dysfunction • Cardiac dysfunction • Abnormal lab values • Low lymphocytes: <1500 / mm3 • Low platelets: < 150,000 / mm3 • Normal lymphocyte count • 1500 - 4000 / mm3 • Normal platelet count • 150,000 - 400,000 / mm3

  44. Medical Charts Include: • Demographic information • Medical history • Illness signs and symptoms • Physical examination findings • Treatment • Laboratory testing results

  45. Epidemiologic Context Potential exposure to H5N1 • Occupational exposure • Animal culler, veterinarian, health care workers • Residence or travel in area affected by H5N1 outbreaks in birds or animals (e.g., poultry market) • Direct contact with dead or diseased birds or other animals in affected area • Close contact with a person with H5N1 virus infection, unexplained moderate or severe acute respiratory illness Warning!Even if NO reports of ill poultry in a location, there could be disease in that area, especially if poultry influenza vaccines are used

  46. Sample Patient Chart:Exposure History Contact with ill people? (If yes, date and name, relationship to patient) ___________________________________________ ___________________________________________ Contact with diseased poultry (Live or dead)? (If yes, date and location) ___________________________________________ ___________________________________________ Recent travel? (If yes, date and location) ___________________________________________ ___________________________________________ Other close patient contacts (Household members, close coworkers) ___________________________________________ Are any of these contacts ill?

  47. Review Question #5 What are the critical pieces of epidemiologic information that must be collected from a patient with illness that is clinically compatible with Influenza A (H5N1) infection? Answer: • Occupational exposure - Animal culler, veterinarian, health care workers • Residence or travel in area affected by H5N1 outbreaks in birds or animals (e.g., poultry market) • Direct contact with dead or diseased birds or other animals in affected area • Close contact with a person with H5N1 virus infection, unexplained moderate or severe acute respiratory illness

  48. Use All Information • Clinical signs compatible with H5N1 virus infection • History suggests exposure to H5N1 virus • Are there multiple cases or respiratory deaths in the same family or in contacts? • Send samples for laboratory confirmation

  49. Specimen Collection and Diagnostics

  50. Diagnostic and Laboratory TestingSuspected Human H5N1 Case Clinical specimen collection Diagnostic tests Laboratory testing Imaging Chest X-ray 50