Susceptibility to infection with Bordetella pertussis re-emerges several years after pertussis vaccination. However, the duration of immunity after natural infection with B. pertussis, postulated to be lifelong, is not known. In an ongoing study, the longitudinal course of pertussis antibodies in patients who have had laboratory-confirmed pertussis is being followed using sera obtained at irregular intervals. In 4 patients a reinfection with Bordetella pertussis is described respectively 7 (patient A), 12 (patients B and C) and 3.5 (patient D) y after the first infection. It seems that the longer the interval between the infections the more severe the complaints.
Conclusion: To the authors' knowledge. these are the first patients in whom symptomatic reinfection with B. pertussis has definitely been proven by laboratory confirmation of both episodes. Bordetella pertussis infection should be considered in patients with symptoms of typical or atypical whooping cough, irrespective of their vaccination status or previous whooping cough.