Bordetella pertussis is a Gram-negative, aerobic, pathogenic, encapsulated coccobacillus bacterium of the genus Bordetella. It is the causative agent of pertussis or whooping cough. Despite widespread vaccination, B. pertussis continues to cause illness and death worldwide due to declining immunity and pathogen adaptation. Its virulence factors include pertussis toxin, adenylate cyclase toxin, filamentous haemagglutinin, pertactin, fimbria, and tracheal cytotoxin.
B. pertussis is an obligate human pathogen and is transmitted through airborne droplets. The disease's incubation period averages 7–10 days, however the range is anywhere from 6–20 days. The bacterium attaches to the ciliated epithelial cells lining the respiratory tract using specialized surface proteins to remain in place. It then releases toxins that disrupt normal cellular functions and cause symptoms in its human host, the only known reservoir for B. pertussis.