Bordetella bronchiseptica (Bb) is a primary pathogen of domestic cats particularly in high population density conditions such as some rescue shelters and multicat households.
Bordetella pertussis, Bordetella parapertussis and Bb are closely related Gram-negative coccobacilli that colonize the respiratory tracts of mammals. B. pertussis is a strict human pathogen and is the primary etiologic agent of whooping cough. B. parapertussis can also cause whooping cough, and B. bronchiseptica is the most promiscuous member of this taxonomic cluster and causes chronic respiratory infections in a wide range of animals including cats, dogs, rabbits, pigs and humans. Sequence analysis indicates that B. parapertussis and B. pertussis are independent derivatives of Bb-like ancestors. During the evolution of these two host-restricted species there was large-scale gene loss and inactivation; host adaptation seems to be a consequence of loss, not gain, of function, and differences in virulence may be related to loss of regulatory or control functions [Parkhill et al., 2003].
Bb is acquiring relevance because of its increased importance as a human pathogen [Woolfret and Moody 1991; Bauwens et al 1992]. Most cases in humans are in immunocompromised patients and lack a clear link with exposure to animals. There is no evidence to support zoonotic infection between cats and people. However, there is one report describing possible human infection from a rabbit [Gueirard et al 1995] and a report describing two Bb infections in pediatric lung transplant recipients. In the latter case pet dogs were suspected to be the origin of infection [Ner et al 2003]. Therefore, it seems sensible to consider Bb as a rare but potential zoonotic infection.