B. parapertussis is a less frequent cause of whooping cough. Thebacteria are responsible for only about 5% of cases of whooping cough. They relatively cause mild disease. B. parapertussis organ-isms differ from B. pertussis by their ability to grow on nutri-ent agar and to produce larger colonies, but the former do not produce pigment (Table 39-3). They are antigenically different from those of B. pertussis. Pertussis vaccine does not confer any protection against B. parapertussis.