Bordetella pertussis, the causative agent of whooping cough, has remained endemic and there is a resurgence in some countries despite vaccination. Bordetella pertussis produces a wide range of virulence factors which are assumed to play an important role in infection and transmission, including tracheal colonization factor (TcfA). Here we show that clinical isolates belonging to distinct lineages may lose their ability to produce TcfA. Irreversible and reversible loss occurred, respectively, by recombination between repeats leading to deletion of the tcfA gene and by mutations in a polymorphic G-track. These phenomena may reflect adaptation to distinct niches.