viral pneumonias

1. Viral pneumonia
Dr George Mothi Justin
Consultant Pulmonologist
Medical trust Hospital

2.  Previously healthy
 54yr old lady
 was referred from a local hospital
 Progressive respiratory failure
 Following a febrile illness x 2-3 days
 Admitted to the ICU in respiratory distress

7.  Blood counts were normal
 Mild renal failure
 Started on

 Antiviral (Oseltamivir – 150 mg twice daily) & I/V
broad-spectrum antibiotics
Supplemental high flow oxygen
 Blood culture & urine culture -negative
 ABG’s s/o ARDS
 Intubated & mechanically ventilated

9.  Weaned & extubated on Day 7
 Clinical & radiological improvement

11. Viral Pneumonia
 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
 Viral pneumonias – when viruses are aetiological
agents

12. WHY HAS VIRAL PNEUMONIAS
BECOME IMPORTANT?
 Incidence of viral pneumonia has increased during
the past decade
 Increase in population of at-risk groups & patients
who are immunocompromised

13.  Emergence of
Severe acute respiratory syndrome (SARS),
Avian influenza A (H5N1) virus,
2009 pandemic influenza A (H1N1) virus
 Discovery of new respiratory viruses
Human metapneumovirus
Coronaviruses - NL63 and HKU1
Hantavirus
Human bocavirus
 Availability of molecular diagnostic assays (such as PCR)

14. Etiology




Adenoviridae (adenoviruses)
Coronaviridae (coronaviruses)
Bunyaviridae (arboviruses) -Hantavirus
Orthomyxoviridae (orthomyxoviruses) - Influenza
virus
Papovaviridae (polyomavirus) – JC virus, BK virus
Paramyxoviridae (paramyxoviruses) -Parainfluenza
virus (PIV), respiratory syncytial virus (RSV), human
metapneumovirus (hMPV), measles virus



15.  Picornaviridae (picornaviruses) – Enteroviruses,
coxsackievirus, echovirus, enterovirus 71,
rhinovirus
 Reoviridae (rotavirus)
 Retroviridae (retroviruses)- HIV , human
lymphotropic virus type 1 (HTLV-1)

16. Immunocompetent Host
 Influenza virus
 Respiratory syncitial Virus (RSV)
 Parainfluenza virus (PIV)
 Adenovirus
 Measles
 Varicella Zoster virus

17. Immunocompromised Host
 Cytomegalovirus (CMV)
 Herpes Simplex Virus (HSV)
 Varicella Zoster Virus (VZV)
 Adenoviruses
 Respiratory syncitial Virus (RSV)
 Parainfluenza Virus
 Rhinovirus
 Measles- Giant cell pneumonia

18. Emerging Viruses
 Hantavirus Pulmonary Syndrome
 SARS
 Associated with significant mortality
 covid19

19. Brief discussion
 Viral pneumonia  Mild and self-limited
illness to a Life-threatening disease
 Four Most commom viruses encountered
4. Influenza virus
5. Respiratory syncytial virus (RSV)
6. Adenovirus
7. Parainfluenza virus

20.  Influenza virus types A and B are responsible for
more than half of all community-acquired viral
pneumonia cases
 Outbreaks of adenovirus of various serotypes
frequently occur in military recruits
 Adenovirus type 14 (Ad 14), a new variant in the
United States, has been shown to cause severe and
sometimes fatal acute respiratory illness

21.  Viruses cause 13-50% of pathogen-diagnosed
community-acquired pneumonia
 8-27% of cases are mixed bacteria-virus
 RSV 1-4%, adenovirus 1-4%, PIV 2-3 %,
hMPV 0-4%, coronavirus  1-14% of pathogen-
diagnosed pneumonia

22.  Influenza is high in elderly persons
 63% of the 300,000 influenza-related
hospitalizations and 85% of 36,000 influenza-related
deaths occur in patients aged 65 years or older
 RSV is the most common etiology of viral
pneumonia in infants and children and second most
common viruses in elderly
 Parainfluenza infection is the second most common
viral illness in infants
 Adenovirus accounts for 10% of pneumonias in
children

23.  Viral pneumonia in pregnancy often underdiagnosed
 Influenza virus, VZV, and measles virus most common viruses in
pregnancy
 Infection  Acute respiratory decompensation/ Respiratory
failure/ARDS  maternofetal hypoxia, preterm labor, multisystem
organ failure, and even death
 Influenza pneumonia & VZV pneumonia  lethal with mortality rates
of 35-40% in pregnant women, compared with 10% in the general
population.
 Pregnant women with viral pneumonia have a higher risk for
severe disease than other females
Viral Pneumonia in Pregnancy

24.  Men who are infected develop viral pneumonia at a
slightly higher rate than women
 Most viruses that can cause pneumonia generally
infect children and cause a mild illness; healthy
adults also develop mild disease
 Elderly persons and persons who are
immunosuppressed develop severe viral pneumonia

25. 
Covid pandemic infection occurred in
outbreaks.
2009-2010 H1N1 influenza pandemic -
infection was more common in the
population aged 5-59 years than in the
elderly
Reason could be lack of exposure and thus
immunity, to the 1957 (and earlier) H1N1
influenza strain

26. Antigenic Shift vs Drift
 Antigenic drift is a gradual continuous
ongoing process that results in the
emergence of new strain variants.
 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
 Usually associated with pandemics

28. Pathophysiology
 Respiratory viruses multiply in the epithelium
of the upper airway and secondarily infect the
lung by means of airway secretions or
hematogenous spread
 Severe pneumonias may result in extensive
consolidation of the lungs with varying
degrees of hemorrhage

29.  The mechanism of damage to tissues
2. Cytopathic
3. Over exuberant inflammation
 Immune responses
6. Type 1 cytokines - promote cell-mediated
immunity
7. Type 2 cytokines - mediate allergic responses.

30.  Cell-mediated immunity appears to be
important for recovery from certain
respiratory viral infections
 Impaired type 1 response may explain why
immunocompromised patients have more
severe viral pneumonias

31. Figure 1. Photomicrograph (original magnification, ×100; hematoxylin-eosin stain) of a lung
biopsy specimen from a 36-year-old man with pneumonia due to herpes simplex virus type 1
shows a fibrous exudate (large arrows) along the alveolar walls.
Kim E A et al. Radiographics 2002;22:S137-S149
©2002 by Radiological Society of North America

32.  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
 RSV infections can alter bacterial colonization
patterns, increase bacterial adherence to respiratory
epithelium, reduce mucociliary clearance, and alter
bacterial phagocytosis by host cells.

33. Transmission

34. Diagnosis of Viral Pneumonia

35. History
 Fever, myalgia, malaise
 Upper respiratory symptoms
 Cough (with or without sputum production)
 Tachypnea and/or dyspnea
 Tachycardia or bradycardia
 Wheezing
 Rhonchi
 Rales

36.  Sternal or intercostal retractions
 Dullness to percussion
 Decreased breath sounds
 Pleurisy
 Friction rub
 Hypoxia, Cyanosis
 Acute respiratory distress syndrome

37. Influenza Pneumonia
 Especially affects


Children with cystic fibrosis or transplants
Adults with chronic cardiovascular or respiratory
disease, diabetes mellitus, renal diseases,
hemoglobinopathies, or immunosuppression
Residents of nursing homes or chronic care
facilities
Healthy adults older than 65 years.




38. Influenza Pneumonia
 The 3 clinical forms of influenza pneumonia
are



primary influenza pneumonia,
secondary bacterial pneumonia, and
mixed viral and bacterial pneumonia

39. Laboratory diagnosis of viral
pneumonia
 Detection of virus or viral antigen in upper-
respiratory secretions by culture or
immunofluorescence microscopy
 Measurement of antibodies in paired serum
samples.
 PCR has increased the ability to detect
respiratory viruses

40. ARE THESE SIMPLE and
ACCURATE TESTS?
 Specimens from the lower-respiratory tract can be
hard to obtain
 Distinguishing prolonged shedding from colonization
can be difficult
 Detection of a virus in the nasopharynx could
represent coincidental upper-respiratory infection or
a pneumonia pathogen.

41.  Viral cultures are still the criterion standard
for most viral pathogens, but they take a long
time to complete
 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
 PCR-based tests with single, multiplex, and
real-time readings have sensitivity better than
that of cultures

42. Cytologic Evaluation
Types of specimen required
 Respiratory secretions-
nasopharyngeal swabs or wash
Bronchoalveolar lavage samples


 Tissue specimens

43.  Intranuclear inclusions often exist in cells infected
with DNA viruses
 Cytoplasmic inclusions usually are present in cells
infected with RNA viruses
 CMV infection characteristically is associated with
"owl's-eye" cells, which are large cells with
basophilic intranuclear inclusions and a surrounding
clear zone.
 The presence of viral inclusions is diagnostic,
although this method has low sensitivity

44. Viral Culture
 Used for isolation and identification of the pathogen
 Tissue used for culture
4. sputum samples
5. nasopharyngeal washing
6. bronchoalveolar lavage
7. biopsy
 Viral transport medium -consists of enriched broth
containing antibiotics and a protein substrate

45.  The cultures - examined for cytopathogenic
effects and for evidence of viral growth
 Viral growth - detected through
hemadsorption testing by demonstrating
adherence of red blood cells to the cultured
cell monolayer of infected tissue
 Further identification of viruses is
accomplished using immunofluorescence

46.  Viral cultures are of lower yield in RSV infection, human
metapneumo virus infection and coronavirus infection
 Modified cell culture methods called shell vial culture
systems are able to detect certain slow-growing viruses
 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

47. Rapid Antigen Detection
 Provide faster results
 Nasal swabs or washings are easy to obtain
 Immunofluorescence assay and enzyme-linked
immunosorbent assay (ELISA) –
 for the diagnosis of HSV, RSV, influenza viruses A and B,
PIV, CMV, and other respiratory viruses
 ELISA can detect viral antigens, while an
immunofluorescence assay requires the presence of
prepared, intact, infected cells

48. Advantages
 Higher specificity for individual viruses
 Assays remain positive for several days to
weeks, long after the culture technique can
detect viable virus

49. Disadvantages
 The overall sensitivity is lower than that of viral cultures
 Antigen detection methods should be used in conjunction with
cell culture
 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.
 Sensitivity for seasonal influenza in adults ranges between 50%
and 60%, and specificity is greater than 90%.

50. Gene Amplification
 PCR is a highly sensitive and specific technique for
amplifying genes to detect the presence of a virus
 For many viruses, this is the diagnostic test of
choice
 Used in combination with viral culture and
immunocytologic and rapid antigen detection

51.  PCR technology allowed the discovery of such
viruses as RSV, hMPV, and coronaviruses in
causing pneumonias.
 For influenza H1N1 and avian influenza, RT-PCR of
either nasopharyngeal swabs or bronchial aspirates/
sputa is the diagnostic modality of choice.
 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.

52.  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
 The single-step MRT-PCR technique has
high sensitivity and specificity.

53. Serologies
 Measured by
2. Complement fixation
3. Enzyme immunoassay [EIA]
 This method ideally requires a 4-fold rise in
titers.

54.  Requires blood to be drawn in the
convalescent phase
 It is not as useful in the acute management of
the patient
 Serologies are particularly useful for
definitively confirming the diagnosis,
especially the positive results of other
diagnostic tests.

55. Other tests
 White-blood-cell count
 C-reactive protein and procalcitonin
Above biomarkers are raised in individuals
with bacterial pneumonia compared with
patients with viral pneumonia

56.  Levels of procalcitonin -increases within
6–12 h after onset of bacterial infection and
halves daily when infection is controlled
 Procalcitonin greater than 0·5 μg/L support
bacterial infection, whereas repeatedly low
amounts suggest that bacterial infection is
unlikely.

57. Chest X-ray
 Bilateral lung involvement
 Influenza -Perihilar and peribronchial
infiltrates
Progression to diffuse interstitial infiltrates is
observed with severe disease.

58.  Avian influenza pneumonia –
patchy, interstitial, and/or diffuse infiltrates,
consolidation, pleural effusion, and
pneumothorax
 RSV pneumonia -patchy bilateral alveolar
infiltrates and interstitial changes

59.  Adenovirus pneumonia-, bilateral and patchy, ground-glass
infiltrates with a preference for lower lobes
 PIV pneumonia-diffuse interstitial infiltrates or diffuse mixed
alveolar-interstitial infiltrates
 hMPV pneumonia-bilateral, interstitial, and alveolar infiltration in
43% and unilateral infiltration in 57%
 Coronavirus pneumonia- Ground-glass opacities and focal
consolidations, especially in the periphery and subpleural regions
of the lower zones
 VZV pneumonia- Diffuse, fluffy, reticular or nodular infiltrates that
can be rapidly progressive. Pleural effusion and peripheral
adenopathy

60.  CMV pneumonia- 2 patterns
(3) multifocal or miliary pattern
(4) Diffuse interstitial pneumonitis with interstitial
edema
 HSV pneumonia-small centrilobular nodules and
patchy ground-glass opacities and consolidation
 Hantavirus pneumonia-normal chest radiograph
during early disease followed by signs of interstitial
edema, Kerley B lines, peribronchial cuffing, and
indistinct hila

61. Diagnostic Techniques Used for
Viral Pneumonia

62. Treatment and Prevention

64. Oseltamivir
Dosage Recommendation
 Adults 75-mg capsule twice per day
 150mg twice daily in severe forms of the
disease

65.  Oseltamivir or Zanamivir

 for treatment of all hospitalized patients with
suspected or confirmed cases
for outpatients at increased risk for complications
of H1N1 infection

66. Peramivir
 IV Peramivir was approved for patients
 not responded to either oral or inhaled
antiviral therapy and/or
 drug delivery by a route other than IV that
was not expected to be dependable or
feasible

67. Virus Treatment Prevention

68. Influenza Vaccines
 Two types

 Trivalent Inactivated Vaccine (TIV) –
intramuscular
Live attenuated (CAIV)- intranasal
 High-risk groups-





Age<5yrs>50yrs
C/c heart/lung disease
Immunosuppressed
Pregnancy
Health care workers

69. Thank You