It is the causative agent of pertussis. Morphologically, it is a Gram-negative coccobacillus, non-motile, and some strains are encapsulated. In culture, colonies have a shiny, confluent appearance. Because of this, they are described as “aluminium paint”, “bisected pearls”, “mercury drops”, or a “thumbprint appearance”.

Tracheal cytotoxin damages the ciliated respiratory epithelium. This damage is increased further by the release of nitric oxide. Pertussis toxin raises intracellular cAMP by inhibiting the Gi protein, and it also causes lymphocytosis.

The disease typically begins as an upper respiratory infection, followed by a paroxysmal (“whooping”) cough in children. In adults, it is usually less severe and may present as a low-level, chronic dry cough. Even with mild symptoms, adults can still infect susceptible children.

Identification is done by fluorescent staining and PCR of samples from nasopharyngeal swabs, culture on Bordet Gengou medium, and antibody detection by agglutination, indirect haemagglutination, complement fixation, and ELISA.