Bordetella pertussis - Whooping Cough

Key Points

Pertussis (Bordetella pertussis) Diagnosis

• CDC 2010 case definition and classification (see table below)

• Laboratory testing for pertussis diagnosis (see table below)

Diagnosis

Indications for Testing

• Patients with predominant complaint of persistent cough, especially in the absence of fever, sore throat, hoarseness, tachypnea or wheeze

Criteria for Diagnosis

• CDC criteria for Bordetella pertussis infection

Laboratory Testing

• Refer to Key Points tab

Differential Diagnosis

• Chlamydia pneumoniae
• Adenovirus
• Mycoplasma pneumoniae
• Parainfluenza Virus 1, 2, 3
• Influenza
• Asthma
• Acute exacerbation of chronic bronchitis
• Cytomegalovirus
• Legionella pneumophila
• Hantavirus
• Metapneumovirus

Clinical Background

Pertussis is a highly infectious and contagious disease commonly referred to as whooping cough. It is caused by the bacterium Bordetella pertussis.

Epidemiology

• Incidence – 1-5/100,000
  • Recent resurgence of disease in industrialized countries
• Age – peak incidence <6 months or >14 years of age
  • Primarily seen in those with waning immunity from childhood vaccination (immunity begins to wane during early adolescence)
  • Significant incidence in unimmunized infants <1 year
• Occurrence – infection occurs most frequently in late spring and summer
• Transmission
  • Adult and teenage children with common cold symptoms are significant reservoirs of the organism and the source of outbreaks in highly susceptible populations
  • Transmitted by respiratory droplets (B. pertussis causes disease only in humans)
    • Infection rates >90% in susceptible populations

Organism

• B. pertussis is a gram-negative pleomorphic coccobacillus
• Multiple virulence factors are produced that aid in organism attachment and production of disease
  • Pertussis toxin is responsible for many disease effects
• B. parapertussis is a related species that may cause a milder form of pertussis syndrome

Clinical Presentation

• Nonspecific viral upper respiratory tract infection-like symptoms
  • Disease spread often not recognized due to mild symptoms in immunized persons
  • Secondary spread common in families and schools
• After 7-10 day incubation, a prolonged course ensues consisting of 3 overlapping stages
  • Catarrhal (1-2 weeks post infection [PI])
  • Paroxysmal coughing (1-4 weeks PI)
  • Convalescent (4-6 weeks PI)
• Partially immune persons and infants >6 months may not manifest all of the typical symptoms
  • Paroxysmal coughing may be absent
• Classic pertussis is generally diagnosed clinically
  • Inspiratory whoop
  • Lymphocytosis
  • Paroxysmal cough
  • Posttussive vomiting
• Atypical pertussis may occur with mild or absent symptoms in adults and previously vaccinated children
  • Atypical pertussis is common, endemic and usually unrecognized in adults
• Secondary complications
  • Respiratory 
    • Bronchitis
    • Laryngitis
    • Pneumonia
    • Pneumothorax
  • Nonrespiratory
    • Complications resulting from severe cough
      • Epistaxis
      • Rectal prolapse
      • Rib fracture
      • Subconjunctival hemorrhage
    • Central nervous system
      • Deafness
      • Encephalopathy
      • Seizures
    • Hemolytic uremic syndrome
  • Death – fulminant course more common in very young infants

Prevention

• Vaccination
• Pediatric age groups – combined Hib and DTaP
• Adult revaccination
  • ACP recommendation – during teen years, in patients 11-64 years, and conditionally >65 years (Tdap)

Indications for Laboratory Testing

• Tests generally appear in the order most useful for common clinical situations
• Click on number for test-specific information in the ARUP Laboratory Test Directory

Click the plus sign to expand the table of additional tests.

Test Name and Number	Comments
Bordetella pertussis Antibodies, IgA, IgG, and IgM by Immunoblot 2004328 Method: Qualitative Immunoblot	May aid in diagnosis of pertussis in adults with prolonged cough in later stages of the disease; cannot be used to confirm infection
Bordetella pertussis Antibodies, IgA, IgG, and IgM by ELISA with Reflex to Immunoblot 2001775 Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Qualitative Immunoblot	Cannot be used to confirm infection
Bordetella pertussis Antibody, IgG by ELISA 2005268 Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay	Cannot be used to confirm infection
Bordetella pertussis Antibody, IgG by ELISA with Reflex to Immunoblot 2001768 Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Qualitative Immunoblot	Cannot be used to confirm infection
Bordetella pertussis Antibody, IgM by ELISA with Reflex to Immunoblot 2001769 Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Qualitative Immunoblot	Cannot be used to confirm infection
Gram Stain 0060101 Method: Stain/Microscopy
Bordetella pertussis DFA 2004667 Method: Direct Fluorescent Antibody Stain	DFA is not recommended; refer instead to culture or PCR
Bordetella pertussis Antibodies, IgG and IgM by ELISA with Reflex to Immunoblot 2001784 Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Qualitative Immunoblot	Cannot be used to confirm infection
Bordetella pertussis Antibody, IgA by Immunoblot 2004316 Method: Qualitative Immunoblot	Cannot be used to confirm infection
Bordetella pertussis Antibody, IgG by Immunoblot 2004327 Method: Qualitative Immunoblot	Cannot be used to confirm infection
Bordetella pertussis Antibody, IgM by Immunoblot 2004326 Method: Qualitative Immunoblot	Cannot be used to confirm infection