Viral pneumonia


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Viral pneumonia

  1. 1. Viral pneumonia Dr George Mothi Justin Consultant Pulmonologist Medical trust Hospital
  2. 2. <ul><li>Previously healthy </li></ul><ul><li>54yr old lady </li></ul><ul><li>was referred from a local hospital </li></ul><ul><li>Progressive respiratory failure </li></ul><ul><li>Following a febrile illness x 2-3 days </li></ul><ul><li>Admitted to the ICU in respiratory distress </li></ul>
  3. 7. <ul><li>Blood counts were normal </li></ul><ul><li>Mild renal failure </li></ul><ul><li>Started on </li></ul><ul><ul><li>Antiviral (Oseltamivir – 150 mg twice daily) & I/V broad-spectrum antibiotics </li></ul></ul><ul><ul><li>Supplemental high flow oxygen </li></ul></ul><ul><li>Blood culture & urine culture -negative </li></ul><ul><li>ABG’s s/o ARDS </li></ul><ul><li>Intubated & mechanically ventilated </li></ul>
  4. 9. <ul><li>Weaned & extubated on Day 7 </li></ul><ul><li>Clinical & radiological improvement </li></ul>
  5. 11. Viral Pneumonia <ul><li>Pneumonia is syndrome caused by acute infection, usually bacterial, characterized by clinical and/or radiographic signs of consolidation of a part or parts of one or both lungs </li></ul><ul><li>Viral pneumonias – when viruses are aetiological agents </li></ul>
  6. 12. WHY HAS VIRAL PNEUMONIAS BECOME IMPORTANT? <ul><li>Incidence of viral pneumonia has increased during the past decade </li></ul><ul><li>Increase in population of at-risk groups & patients who are immunocompromised </li></ul>
  7. 13. <ul><li>Emergence of </li></ul><ul><li>Severe acute respiratory syndrome (SARS), </li></ul><ul><li>Avian influenza A (H5N1) virus, </li></ul><ul><li>2009 pandemic influenza A (H1N1) virus </li></ul><ul><li>Discovery of new respiratory viruses </li></ul><ul><li>Human metapneumovirus </li></ul><ul><li>Coronaviruses - NL63 and HKU1 </li></ul><ul><li>Hantavirus </li></ul><ul><li>Human bocavirus </li></ul><ul><li>Availability of molecular diagnostic assays (such as PCR) </li></ul>
  8. 14. Etiology <ul><li>Adenoviridae (adenoviruses) </li></ul><ul><li>Coronaviridae (coronaviruses) </li></ul><ul><li>Bunyaviridae (arboviruses) -Hantavirus </li></ul><ul><li>Orthomyxoviridae (orthomyxoviruses) - Influenza virus </li></ul><ul><li>Papovaviridae (polyomavirus) – JC virus, BK virus </li></ul><ul><li>Paramyxoviridae (paramyxoviruses) -Parainfluenza virus (PIV), respiratory syncytial virus (RSV), human metapneumovirus (hMPV), measles virus </li></ul>
  9. 15. <ul><ul><ul><li>Picornaviridae (picornaviruses) – Enteroviruses, coxsackievirus, echovirus, enterovirus 71, rhinovirus </li></ul></ul></ul><ul><ul><ul><li>Reoviridae (rotavirus) </li></ul></ul></ul><ul><ul><ul><li>Retroviridae (retroviruses)- HIV , human lymphotropic virus type 1 (HTLV-1) </li></ul></ul></ul>
  10. 16. Immunocompetent Host <ul><li>Influenza virus </li></ul><ul><li>Respiratory syncitial Virus (RSV) </li></ul><ul><li>Parainfluenza virus (PIV) </li></ul><ul><li>Adenovirus </li></ul><ul><li>Measles </li></ul><ul><li>Varicella Zoster virus </li></ul>
  11. 17. Immunocompromised Host <ul><li>Cytomegalovirus (CMV) </li></ul><ul><li>Herpes Simplex Virus (HSV) </li></ul><ul><li>Varicella Zoster Virus (VZV) </li></ul><ul><li>Adenoviruses </li></ul><ul><li>Respiratory syncitial Virus (RSV) </li></ul><ul><li>Parainfluenza Virus </li></ul><ul><li>Rhinovirus </li></ul><ul><li>Measles- Giant cell pneumonia </li></ul>
  12. 18. Emerging Viruses <ul><li>Hantavirus Pulmonary Syndrome </li></ul><ul><li>SARS </li></ul><ul><li>Associated with significant mortality </li></ul>
  13. 19. Brief discussion <ul><li>Viral pneumonia  Mild and self-limited illness to a Life-threatening disease </li></ul><ul><li>Four Most commom viruses encountered </li></ul><ul><li>Influenza virus </li></ul><ul><li>Respiratory syncytial virus (RSV) </li></ul><ul><li>Adenovirus </li></ul><ul><li>Parainfluenza virus </li></ul>
  14. 20. <ul><li>Influenza virus types A and B are responsible for more than half of all community-acquired viral pneumonia cases </li></ul><ul><li>Outbreaks of adenovirus of various serotypes frequently occur in military recruits </li></ul><ul><li>Adenovirus type 14 (Ad 14), a new variant in the United States, has been shown to cause severe and sometimes fatal acute respiratory illness </li></ul>
  15. 21. <ul><li>Viruses cause 13-50% of pathogen-diagnosed community-acquired pneumonia </li></ul><ul><li>8-27% of cases are mixed bacteria-virus </li></ul><ul><li>RSV  1-4%, adenovirus  1-4%, PIV  2-3 %, hMPV  0-4%, coronavirus  1-14% of pathogen-diagnosed pneumonia </li></ul>
  16. 22. <ul><li>Influenza is high in elderly persons </li></ul><ul><li>63% of the 300,000 influenza-related hospitalizations and 85% of 36,000 influenza-related deaths occur in patients aged 65 years or older </li></ul><ul><li>RSV is the most common etiology of viral pneumonia in infants and children and second most common viruses in elderly </li></ul><ul><li>Parainfluenza infection is the second most common viral illness in infants </li></ul><ul><li>Adenovirus accounts for 10% of pneumonias in children </li></ul>
  17. 23. <ul><li>Viral pneumonia in pregnancy often underdiagnosed </li></ul><ul><li>Influenza virus, VZV, and measles virus most common viruses in pregnancy </li></ul><ul><li>Infection  Acute respiratory decompensation/ Respiratory failure/ARDS  maternofetal hypoxia, preterm labor, multisystem organ failure, and even death </li></ul><ul><li>Influenza pneumonia & VZV pneumonia  lethal with mortality rates of 35-40% in pregnant women, compared with 10% in the general population. </li></ul><ul><li>Pregnant women with viral pneumonia have a higher risk for severe disease than other females </li></ul>Viral Pneumonia in Pregnancy
  18. 24. <ul><li>Men who are infected develop viral pneumonia at a slightly higher rate than women </li></ul><ul><li>Most viruses that can cause pneumonia generally infect children and cause a mild illness; healthy adults also develop mild disease </li></ul><ul><li>Elderly persons and persons who are immunosuppressed develop severe viral pneumonia </li></ul>
  19. 25. <ul><li>2009-2010 H1N1 influenza pandemic - infection was more common in the population aged 5-59 years than in the elderly </li></ul><ul><li>Reason could be lack of exposure and thus immunity, to the 1957 (and earlier) H1N1 influenza strain </li></ul>
  20. 26. Antigenic Shift vs Drift <ul><li>Antigenic drift is a gradual continuous ongoing process that results in the emergence of new strain variants. </li></ul><ul><li>Antigenic shift is a sudden abrupt change in the antigen by which an novel strain of virus is evolved which acquires the capability of infecting human beings </li></ul><ul><ul><li>Usually associated with pandemics </li></ul></ul>
  21. 28. Pathophysiology <ul><li>Respiratory viruses multiply in the epithelium of the upper airway and secondarily infect the lung by means of airway secretions or hematogenous spread </li></ul><ul><li>Severe pneumonias may result in extensive consolidation of the lungs with varying degrees of hemorrhage </li></ul>
  22. 29. <ul><li>The mechanism of damage to tissues </li></ul><ul><li>Cytopathic </li></ul><ul><li>Over exuberant inflammation </li></ul><ul><li>Immune responses </li></ul><ul><li>Type 1 cytokines - promote cell-mediated immunity </li></ul><ul><li>Type 2 cytokines - mediate allergic responses. </li></ul>
  23. 30. <ul><li>Cell-mediated immunity appears to be important for recovery from certain respiratory viral infections </li></ul><ul><li>Impaired type 1 response may explain why immunocompromised patients have more severe viral pneumonias </li></ul>
  24. 32. <ul><li>Respiratory viruses damage the respiratory tract and stimulate the host to release multiple humoral factors, including histamine, leukotriene C4, and virus-specific immunoglobulin E bradykinin, interleukin 1, interleukin 6, and interleukin 8 </li></ul><ul><li>RSV infections can alter bacterial colonization patterns, increase bacterial adherence to respiratory epithelium, reduce mucociliary clearance, and alter bacterial phagocytosis by host cells. </li></ul>
  25. 33. Transmission
  26. 34. Diagnosis of Viral Pneumonia
  27. 35. History <ul><li>Fever, myalgia, malaise </li></ul><ul><li>Upper respiratory symptoms </li></ul><ul><li>Cough (with or without sputum production) </li></ul><ul><li>Tachypnea and/or dyspnea </li></ul><ul><li>Tachycardia or bradycardia </li></ul><ul><li>Wheezing </li></ul><ul><li>Rhonchi </li></ul><ul><li>Rales </li></ul>
  28. 36. <ul><li>Sternal or intercostal retractions </li></ul><ul><li>Dullness to percussion </li></ul><ul><li>Decreased breath sounds </li></ul><ul><li>Pleurisy </li></ul><ul><li>Friction rub </li></ul><ul><li>Hypoxia, Cyanosis </li></ul><ul><li>Acute respiratory distress syndrome </li></ul>
  29. 37. Influenza Pneumonia <ul><li>Especially affects </li></ul><ul><ul><li>Children with cystic fibrosis or transplants </li></ul></ul><ul><ul><li>Adults with chronic cardiovascular or respiratory disease, diabetes mellitus, renal diseases, </li></ul></ul><ul><ul><li>hemoglobinopathies, or immunosuppression </li></ul></ul><ul><ul><li>Residents of nursing homes or chronic care facilities </li></ul></ul><ul><ul><li>Healthy adults older than 65 years. </li></ul></ul>
  30. 38. Influenza Pneumonia <ul><li>The 3 clinical forms of influenza pneumonia are </li></ul><ul><ul><li>primary influenza pneumonia, </li></ul></ul><ul><ul><li>secondary bacterial pneumonia, and </li></ul></ul><ul><ul><li>mixed viral and bacterial pneumonia </li></ul></ul>
  31. 39. Laboratory diagnosis of viral pneumonia <ul><li>Detection of virus or viral antigen in upper-respiratory secretions by culture or immunofluorescence microscopy </li></ul><ul><li>Measurement of antibodies in paired serum samples. </li></ul><ul><li>PCR has increased the ability to detect respiratory viruses </li></ul>
  32. 40. ARE THESE SIMPLE and ACCURATE TESTS? <ul><li>Specimens from the lower-respiratory tract can be hard to obtain </li></ul><ul><li>Distinguishing prolonged shedding from colonization can be difficult </li></ul><ul><li>Detection of a virus in the nasopharynx could represent coincidental upper-respiratory infection or a pneumonia pathogen. </li></ul>
  33. 41. <ul><li>Viral cultures are still the criterion standard for most viral pathogens, but they take a long time to complete </li></ul><ul><li>Viral-antigen detection is one of the new tests, but the results are generally less sensitive and less specific than those of conventional cell cultures </li></ul><ul><li>PCR-based tests with single, multiplex, and real-time readings have sensitivity better than that of cultures </li></ul>
  34. 42. Cytologic Evaluation <ul><li>Types of specimen required </li></ul><ul><li>Respiratory secretions- </li></ul><ul><ul><li>nasopharyngeal swabs or wash </li></ul></ul><ul><ul><li>Bronchoalveolar lavage samples </li></ul></ul><ul><li>Tissue specimens </li></ul>
  35. 43. <ul><li>Intranuclear inclusions often exist in cells infected with DNA viruses </li></ul><ul><li>Cytoplasmic inclusions usually are present in cells infected with RNA viruses </li></ul><ul><li>CMV infection characteristically is associated with &quot;owl's-eye&quot; cells, which are large cells with basophilic intranuclear inclusions and a surrounding clear zone. </li></ul><ul><li>The presence of viral inclusions is diagnostic, although this method has low sensitivity </li></ul>
  36. 44. Viral Culture <ul><li>Used for isolation and identification of the pathogen </li></ul><ul><li>Tissue used for culture </li></ul><ul><li>sputum samples </li></ul><ul><li>nasopharyngeal washing </li></ul><ul><li>bronchoalveolar lavage </li></ul><ul><li>biopsy </li></ul><ul><li>Viral transport medium -consists of enriched broth containing antibiotics and a protein substrate </li></ul>
  37. 45. <ul><li>The cultures - examined for cytopathogenic effects and for evidence of viral growth </li></ul><ul><li>Viral growth - detected through hemadsorption testing by demonstrating adherence of red blood cells to the cultured cell monolayer of infected tissue </li></ul><ul><li>Further identification of viruses is accomplished using immunofluorescence </li></ul>
  38. 46. <ul><li>Viral cultures are of lower yield in RSV infection, human metapneumo virus infection and coronavirus infection </li></ul><ul><li>Modified cell culture methods called shell vial culture systems are able to detect certain slow-growing viruses </li></ul><ul><li>Shell vial culture systems are used widely for earlier detection of CMV, RSV, herpes simplex virus (HSV), adenovirus, influenza viruses, parainfluenza virus (PIV), and other viral pathogens </li></ul>
  39. 47. Rapid Antigen Detection <ul><li>Provide faster results </li></ul><ul><li>Nasal swabs or washings are easy to obtain </li></ul><ul><li>Immunofluorescence assay and enzyme-linked immunosorbent assay (ELISA) – </li></ul><ul><ul><li>for the diagnosis of HSV, RSV, influenza viruses A and B, PIV, CMV, and other respiratory viruses </li></ul></ul><ul><li>ELISA can detect viral antigens, while an immunofluorescence assay requires the presence of prepared, intact, infected cells </li></ul>
  40. 48. <ul><li>Advantages </li></ul><ul><li>Higher specificity for individual viruses </li></ul><ul><li>Assays remain positive for several days to weeks, long after the culture technique can detect viable virus </li></ul>
  41. 49. <ul><li>Disadvantages </li></ul><ul><li>The overall sensitivity is lower than that of viral cultures </li></ul><ul><li>Antigen detection methods should be used in conjunction with cell culture </li></ul><ul><li>RSV rapid antigen detection is useful in young children, who shed high titers of virus, but sensitivity is low in adults (0-20%) when compared with RT-PCR. </li></ul><ul><li>Sensitivity for seasonal influenza in adults ranges between 50% and 60%, and specificity is greater than 90%. </li></ul>
  42. 50. Gene Amplification <ul><li>PCR is a highly sensitive and specific technique for amplifying genes to detect the presence of a virus </li></ul><ul><li>For many viruses, this is the diagnostic test of choice </li></ul><ul><li>Used in combination with viral culture and immunocytologic and rapid antigen detection </li></ul>
  43. 51. <ul><li>PCR technology allowed the discovery of such viruses as RSV, hMPV, and coronaviruses in causing pneumonias. </li></ul><ul><li>For influenza H1N1 and avian influenza , RT-PCR of either nasopharyngeal swabs or bronchial aspirates/sputa is the diagnostic modality of choice . </li></ul><ul><li>PCR has become especially useful for the detection of CMV in various body fluids (eg, blood, urine) in severely immunocompromised patients, particularly hematopoietic stem cell transplant (HSCT) recipients. </li></ul>
  44. 52. <ul><li>Multiplex reverse transcriptase polymerase chain reaction (MRT-PCR), permits rapid detection of influenza virus types A and B, RSV (types A and B), adenoviruses, PIV (types 1, 2, and 3), hMPV, and rhinovirus </li></ul><ul><li>The single-step MRT-PCR technique has high sensitivity and specificity. </li></ul>
  45. 53. Serologies <ul><li>Measured by </li></ul><ul><li>Complement fixation </li></ul><ul><li>Enzyme immunoassay [EIA] </li></ul><ul><li>This method ideally requires a 4-fold rise in titers. </li></ul>
  46. 54. <ul><li>Requires blood to be drawn in the convalescent phase </li></ul><ul><li>It is not as useful in the acute management of the patient </li></ul><ul><li>Serologies are particularly useful for definitively confirming the diagnosis, especially the positive results of other diagnostic tests. </li></ul>
  47. 55. Other tests <ul><li>White-blood-cell count </li></ul><ul><li>C-reactive protein and procalcitonin </li></ul><ul><li>Above biomarkers are raised in individuals with bacterial pneumonia compared with patients with viral pneumonia </li></ul>
  48. 56. <ul><li>Levels of procalcitonin -increases within </li></ul><ul><li>6–12 h after onset of bacterial infection and halves daily when infection is controlled </li></ul><ul><li>Procalcitonin greater than 0·5 μg/L support bacterial infection, whereas repeatedly low amounts suggest that bacterial infection is unlikely. </li></ul>
  49. 57. Chest X-ray <ul><li>Bilateral lung involvement </li></ul><ul><li>Influenza -Perihilar and peribronchial infiltrates </li></ul><ul><li>Progression to diffuse interstitial infiltrates is observed with severe disease. </li></ul>
  50. 58. <ul><li>Avian influenza pneumonia – </li></ul><ul><li>patchy, interstitial, and/or diffuse infiltrates, consolidation, pleural effusion, and pneumothorax </li></ul><ul><li>RSV pneumonia - patchy bilateral alveolar infiltrates and interstitial changes </li></ul>
  51. 59. <ul><li>Adenovirus pneumonia- , bilateral and patchy, ground-glass infiltrates with a preference for lower lobes </li></ul><ul><li>PIV pneumonia-diffuse interstitial infiltrates or diffuse mixed alveolar-interstitial infiltrates </li></ul><ul><li>hMPV pneumonia-bilateral, interstitial, and alveolar infiltration in 43% and unilateral infiltration in 57% </li></ul><ul><li>Coronavirus pneumonia- Ground-glass opacities and focal consolidations, especially in the periphery and subpleural regions of the lower zones </li></ul><ul><li>VZV pneumonia- Diffuse, fluffy, reticular or nodular infiltrates that can be rapidly progressive. Pleural effusion and peripheral adenopathy </li></ul>
  52. 60. <ul><li>CMV pneumonia- 2 patterns </li></ul><ul><li>multifocal or miliary pattern </li></ul><ul><li>Diffuse interstitial pneumonitis with interstitial edema </li></ul><ul><li>HSV pneumonia- small centrilobular nodules and patchy ground-glass opacities and consolidation </li></ul><ul><li>Hantavirus pneumonia- normal chest radiograph during early disease followed by signs of interstitial edema, Kerley B lines, peribronchial cuffing, and indistinct hila </li></ul>
  53. 61. Diagnostic Techniques Used for Viral Pneumonia
  54. 62. Treatment and Prevention
  55. 64. Oseltamivir <ul><li>Dosage Recommendation </li></ul><ul><li>Adults  75-mg capsule twice per day </li></ul><ul><li>150mg twice daily in severe forms of the disease </li></ul>
  56. 65. <ul><li>Oseltamivir or Zanamivir </li></ul><ul><ul><li>for treatment of all hospitalized patients with suspected or confirmed cases </li></ul></ul><ul><ul><li>for outpatients at increased risk for complications of H1N1 infection </li></ul></ul>
  57. 66. Peramivir <ul><li>IV Peramivir was approved for patients </li></ul><ul><li>not responded to either oral or inhaled antiviral therapy and/or </li></ul><ul><li>drug delivery by a route other than IV that was not expected to be dependable or feasible </li></ul>
  58. 67. Virus Treatment Prevention
  59. 68. Influenza Vaccines <ul><li>Two types </li></ul><ul><ul><li>Trivalent Inactivated Vaccine (TIV) – intramuscular </li></ul></ul><ul><ul><li>Live attenuated (CAIV)- intranasal </li></ul></ul><ul><li>High-risk groups- </li></ul><ul><ul><li>Age<5yrs>50yrs </li></ul></ul><ul><ul><li>C/c heart/lung disease </li></ul></ul><ul><ul><li>Immunosuppressed </li></ul></ul><ul><ul><li>Pregnancy </li></ul></ul><ul><ul><li>Health care workers </li></ul></ul>
  60. 69. Thank You Thank You