Overview of Respiratory Agents:

1
Overview of Respiratory Agents

• Bruce Gamage
• Infection Control Consultant
• BC Centre for Disease Control

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The Agents

• Viruses
• Rhinoviruses
• Coronaviruses
• Adenoviruses
• Parainfluenzaviruses
• Respiratory Syncytial virus
• Influenza viruses

• Bacteria
• Grp A Streptococci
• Pneumococcal Pneumonia
• Pertussis
• Legionella

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Respiratory Tract
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Associated Illnesses

• Rhinitis - Swelling of nasal mucosa, excessive
  nasal discharge
• Pharyngitis (sore throat) - About 40 viral
  etiology
• Laryngitis Hoarsness (vocal chords)
• Bronchitis
• Bronchiolitis
• Pneumonia

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Rhinovirus
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Rhinoviruses

• Approximately 100 serotypes of human rhinovirus
• Major etiologic agent of common cold
• Incubation 2-4 days Duration 1 week to 2 weeks
  
• Transmission is mainly by hand and environmental
  contamination
• Pharyngitis may progress to laryngitis and
  bronchitis with cough
• Peak in fall and spring

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Coronavirus
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Coronaviruses

• Types 229E, B814, OC43
• Similar to rhinoviruses 30 of common colds
• SARS-CoV a novel coronavirus
• Fever, cough, atypical pneumonia
• Incubation 3-10 days Duration weeks
• 23-32 of patients become critically ill
  requiring intubation 4-12 case fatality
• Seasonal?

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Adenovirus
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Adenoviruses

• 49 serotypes of human adenovirus
• Incubation 6-10 days Incidence is year round.
• Transmission environmental, hand to mouth, nose,
  eye
• Clinical features
• Acute febrile pharyngitis cold-like illness in
  children.
• Pharyngo-conjunctival fever. Outbreak related.
  Swimming pool conjunctivitis.
• Acute respiratory disease (ARD)
• Pharyngitis fever cough military recruits.
• Pneumonia complication of respiratory disease.
  High mortality.
• Epidemic keratoconjunctivitis associated with
  eye trauma.
•  

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Parainfluenzavirus
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Parainfluenzavirus

• 3 serotypes, Parainfluenza 1, 2 and 3
• Incubation 3-6 days shedding 3-10 days 3-4 wks
  (children)
• Transmission person to person direct contact or
  large droplets
• Seasonal incidence
• Type 3 year round disease
• Type 1, 2 epidemics of croup in the fall

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Parainfluenzavirus

• Clinical features
• -Asymptomatic infections (lt50).
• -Parainfluenza viruses are leading cause of
  croup.
• -Cold-like symptoms and bronchitis are common.
• -Parainfluenza 1,2 predominantly croup.
• -Parainfluenza 3 croup, bronchiolitis and
  pneumonia.

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Respiratory Syncytial Virus
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Respiratory Syncytial Virus

• Types A and B with several subtypes
• Incubation 5 days (2-8) shedding 4-6 days 3-4
  wks (children)
• Transmission person to person direct contact or
  large droplets
• Seasonal incidence Winter-spring. Occurs yearly
  
• Nosocomial infections
• major problem staff/patient cycle

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Respiratory Syncytial virus

• Clinical features
• Primary infection in children up to 3 yrs.
• mostly symptomatic
• Begin as URI and pharyngitis, fever up to 40?C,
  pronounced cough.
• 2-4 days later bronchiolitis and pneumonia
  develop
• Otitis media is a common complication.
• Secondary infection
• In children presents as URI with
  tracheobronchitis.
• In adults URI bronchopneumonia

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Influenza Viruses
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Influenza viruses

• Types A (H1N1, H3N2, yearly variations, animal
  strains), B (limited variations)
• Transmission
• droplets, small particle aerosols lt10µm sporadic
  outbreaks and epidemics.
• virus is shed from day 1 to 7 prolonged in
  children (foci)

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Influenza viruses

• Incubation18 to 72 hours dose related.
• Seasonal incidence winter spring epidemic lasts
  6-8 weeks.
•  Pandemic Every 10-40 years
• Age all ages are susceptible with the elderly at
  highest risk.

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Influenza viruses

• Clinical features
• Abrupt onset fever, chills, fatigue, muscle
  aches, headache, eye pain,
• scratchy throat, cough.
• Fever lasts 2-5 days cough may persist
• Convalescence is lengthy with tiredness and
  depression.
• Complications viral pneumonia secondary
  bacterial infections

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Influenza viruses

• Antigenic Drift
• Influenza A virus undergoes small antigenic
  changes almost yearly in the HA and NA proteins.
  Such a change results in a new influenza epidemic
   
• Antigenic Shift-
• Every few decades (10-30 yrs) new strains of
  influenza A arise which contain new genes for the
  HA or NA and others that are derived from animal
  influenza viruses. Such occurrences result in an
  influenza pandemic. These have high levels of
  morbidity and mortality

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Influenza Prevention

• Vaccination
• influenza viruses isolated during our spring and
  fall and in the southern hemisphere are typed.
• New antigenic types are incorporated into
  vaccine.
• The vaccine formulation varies every year.
• contains Influenza A and B viruses

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Influenza Prevention

• Antiviral agents
• Amantidine and rimantidine.
• effective against influenza A but not to B.
• control of institutional outbreaks. Given to all
  residents simultaneously
• Zanamivir (Relenza) and oseltamivir (Tamiflu)
• Active on Flu A and B.
•  

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Group A Streptococcus
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Group A Streptococcus

• Approximately 80 different serotypes
• Transmission large droplets or direct contact
• Incubation Period short usually 1-3 days
• Age population is generally susceptible
  repeated attacks of sore throat due to different
  serotypes

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Group A Streptococcus

• Clinical Features
• Sudden onset of fever, sore throat may include
  tonsillitis or pharyngitis
• Also associated with skin infections, scarlet
  fever, rheumatic fever and toxic shock syndrome
• Educate the public re prompt diagnosis and
  completion of antibiotics

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B. pertussis
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Pertussis

• Caused by the pertussis bacillus
• Transmission direct contact or probably airborne
  droplets often brought home to young children by
  older siblings
• Incubation period 7-20 days
• Age usually young children but becoming more
  common in adolescents and adults who have been
  immunized but have waning immunity

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Pertussis

• Clinical features
• Insidious onset with irritating cough that
  becomes paroxysmal within 2 weeks and may last 2
  months cough has characteristic whoop and
  often causes vomiting
• Most contagious before paroxysmal stage
• Educate public re importance of immunization
  starting a 2 months highest mortality in infants
  lt1 yrs. Adolescent revaccination?
• Prophylactic antibiotics to close contacts in
  outbreaks

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S. Pneumoniae
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Pneumococcal Pneumonia

• Caused by streptococcus pneumonia of 83 known
  types, 23 account for 90 of pneumonias
• Transmission by direct droplet spread, direct
  contact or contact with soiled articles
• Incubation period May be short as 1-3 days
• Age Elderly persons and chronically ill and
  children lt2 yrs

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Pneumococcal Pneumonia

• Clinical Features
• Sudden onset of shaking, chills, fever, pleural
  pain and productive cough with rusty sputum
• Prompt treatment with penicillin G (if sensitive)
• Promote vaccination to high risk groups

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Legionellae
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Legionella

• Causes Legionnaire's disease and Pontiac Fever
• Transmission airborne transmission in water from
  hot water systems, cooling towers, respiratory
  equipment, humidifiers not transmitted
  person-to-person
• Age occurs more frequently with increasing age
  (rarely seen in lt20 yr). Several outbreaks
  occurred in hospitalized patients

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Legionella

• Clinical Features
• Both begin with loss of appetite, fatigue and
  headache rapid onset of high fever (gt39C).
• Legionnaires leads to bilateral pneumonia with
  39 fatality rate in hospitalized patients.
• Pontiac fever is not associated with pneumonia or
  death patients recover in 3-5 days.

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Legionella

• Prevention
• Cleaning towers should be drained and
  mechanically cleaned periodically tap water
  should not be used in respiratory therapy
• Guidelines for prevention in domestic tap water?