Bordetella Species

Classical Non-classical
• pertussis (type species)
• parapertussis
• bronchiseptica • ansorpii
• avium
• broncialis
• flabilis
• hinzii
• holmesii
• petrii
• sputigena
• trematum
& 4 other species not associated with human infection

NB: spp. in underline = not strictly aerobic

History

| Site | Human URT (we are only reservoir for B.pertussis) | | --- | --- | | Transmission | Airborne droplets | | Risk Factors | <1yrs Children & adolescents Unvaccinated | | Clinical syndromes | NB: Notifiable disease Incubation: 7-10d (range 6-20d)

Features:

Phases of illness

  1. Catarrhal: Coryza, fever, cough, conjunctival injection (1-2wks)
  2. Paroxysmal: paroxysmal cough; afebrile; whoop . Worse at night.
  3. Convalescent: slow-resolving cough (months).

Complications:

Confirmed: Sx of pertussis + 1 of: • +ve Respiratory sample (NPA/NPS/PNS) • +ve Respiratory PCR • anti-pertussis toxin IgG titre >70 IU/ml (serum) or >70 aU (OF) (NB: in the absence of vaccination in the past year)

Epidemiologically linked: Sx of pertussis & was in close contact with Confirmed case within 21d onset of their cough

(Close contact: Household, overnight stay in same room) | | Risk groups (UKHSA 2024) | Group 1: Vulnerable infants A. Unimmunised infants (born <32wks) <2 months old regardless of maternal vaccine status. B. Unimmunised infants (born >32 weeks) <2 months old whose mothers did not receive pertussis vaccine after 16 weeks & >2 weeks before delivery. C. Infants 2 - 5 months, regardless of maternal vaccination status or gestational age at delivery. D. Infants from 5 - 12 months who aren’t fully vaccinated.

Group 2: Individuals who could transmit to Group 1, and haven’t received vaccine in last 5 years (but >7d ago) A. 32+wks Pregnant women B. HCWs who provide close personal care to Group 1 infants & pregnant women. C. People whose work involves regular, close & prolonged contact with Group 1 infants. D. People who share a household with a Group 1 infant. |

Pathogenic Mechanisms

Toxin Seen in MoA Effect
Pertussis Toxin B.pertussis AB toxin.
Increased intracellular cAMP —> alters signalling. Inhibits G-protein chemokine receptors in cell. Reduced phagocyte recruitment/chemotaxis. Reduced chemokine synthesis by affected cell
Adenylate cyclase toxin pertussis, parapertussis, bronchiseptica RTX toxin.
Binds Complement receptor 3 on phagocytes —> Cytotoxic pores —> Ca influx / K+ efflux —> damages cell. Also has IC Adenylate Cyclase activity —> increased cAMP. Inhibit phagocyte activity
Filamentous hæmagglutinin pertussis Attachment factor for adherence to host cells Biofilm formation
Pertactin pertussis, bronchiseptica Adhesion to epithelial cells
Fimbria An ‘attachment pilus’ Adherence to cells; biofilm formation
Tracheal cytotoxin pertussis (also N.gonorrhoea, Vibrio fischeri) Soluble peptidoglycan; damages ciliated cells —> impaired mucus removal from URT —> paroxysmal (whooping) cough Reduced pathogen removal

Lab diagnostics

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Testing in primary care: