Pertussis (whooping cough) is a highly contagious upper respiratory tract infection, caused by
Bordetella pertussis. This disease is particularly serious in infants, mostly in those younger than 6
months that have not, or only partially, been vaccinated. Since the introduction of a global anti- B.
pertussis vaccination program, the incidence of pertussis has considerably decreased in the past few
decades.
In Switzerland, global letality rate is 0.05 deaths/1000 cases. This rate is four time higher in children
from 0-5 years old (0.2 deaths/1000 cases), and even greater in infants under 3 months (10
deaths/1000 cases). (1)
Causative agent of pertussis, Bordetella pertussis, is a gram-negative coccobacillus, whose humans are
the only known reservoir. B. pertussis is spread by airborne droplets and binds to the epithelial cells of
the trachea, bronchi and bronchioles thanks to its virulence factors. These include filamentous
hemaglutinin, an adhesin that promotes adhesion to ciliated respiratory epithelial cells and
phagocytosis by macrophages in view to upgrade bacterial survival, Pertussis toxin, a factor promoting
systemic effects, such as lymphocytosis and adenylate cyclase toxin, inhibing anti-bacterial functions
of innate cells. (2)