Prevalence of markers of exposure to Bordetella pertussis among Italian young adults.

Abstract

Titers of serum antibody and cell-mediated immunity (CMI) to Bordetella pertussis antigens were assessed in a cohort of Italian military school students for whom the coverage of pertussis vaccination was low. The overall prevalence of IgG antibody above the minimum level of detection (MLD) was 71.6% for pertussis toxin (PT), 81% for pertactin (PRN), and 99% for filamentous hemagglutinin (FHA). Levels of IgA antibody to PT above the MLD were detected in 15.9% of the study participants. CMI to FHA, PRN, and PT was positive in 97%, 100%, and 82% of tested individuals, respectively. Only 9.7% of the participants had neither antibody nor CMI specific to B. pertussis antigens. In the 5-month clinical, microbiological, and serological follow-up conducted during a high-risk period of pertussis, no cases of pertussis were detected. These data, in particular CMI, demonstrate that most Italian young adults are specifically primed against B. pertussis, which should be taken into consideration when future policy on pertussis vaccination is being made in Italy.