Aetiology

Bordetella pertussis is the typical aetiological agent.[1]​ Other Bordetella species, including B parapertussis, B bronchiseptica, and B holmesii, sometimes cause pertussis-like illnesses.[2][10]

Pathophysiology

Humans are the only known host of Bordetella pertussis.[2] Pertussis is highly contagious, with up to 80% of susceptible household contacts developing clinical disease after exposure to an index case. Infection is transmitted person-to-person via respiratory droplets and airborne particles generated by coughing and sneezing or via fomites contaminated with respiratory secretions.[1]​​[2] Transmission is most frequent in the first 1-2 weeks of infection; patients typically remain infectious for 2-3 weeks from the onset of cough if untreated. The incubation period is generally 7-10 days, with a range of 4-21 days.[1]​​[10] Bacteria adhere to ciliated respiratory epithelial cells, where they produce toxins and other biologically active mediators, causing ciliary paralysis, local tissue damage, and inflammation.[4]​​​ A characteristic lymphocytosis is caused by pertussis toxin. B pertussis can enter and survive within phagocytic leukocytes and non-phagocytic cells, but it is unclear how this affects the disease and the host immune response. B pertussis infection can result in a primary pertussis pneumonia. Bacteraemia does not occur. Infection elicits immune responses to a variety of bacterial antigens, but immunity is not permanent.[6][7][11][12]

Use of this content is subject to our disclaimer