Bordetella pertussis and pertactin-deficient clinical isolates: lessons for pertussis vaccines.

Bordetella pertussis causes whooping cough in humans, a highly transmissible respiratory disease life threatening for unvaccinated infants. Vaccination strategies were thus introduced worldwide with great success in developed countries reaching high vaccine coverage with efficacious vaccines. In the late 20th/early 21st century, acellular pertussis vaccines replaced whole cell pertussis vaccines but B. pertussis still circulates and evolves in humans, its only known reservoir. The latest transformation of this pathogen, and of its close relative Bordetella parapertussis, is the loss of pertactin production, a virulence factor included in different acellular pertussis vaccines. The real impact of this evolution on acellular pertussis vaccines efficacy and effectiveness should be assessed through standardized surveillance and isolation of B. pertussis and B. parapertussis worldwide.