The main risk factor for the extreme ages of life:
* Infants (age less than 6 months and certainly less than two months).
In infants, pertussis can be very serious or even fatal (5). The majority of deaths occur in infants younger than 6 months.
* Seniors: because of their fragility.
Pregnant women are another risk category.
Finally, point out that there are professions contamination as caregivers because of their contact with the elderly, children, infants under 6 months or more students in medical and paramedical courses. (3)