Seroprevalence of pertussis antibodies among adolescents in Israel

Background: There is an increasing number of reports of pertussis among old er children and adults. The development and licensure of an acellular pertu ssis vaccine offer the possibility of adult vaccination against the disease . Information on immunity to pertussis in this age group is needed before a ny vaccination policy can be considered. Objectives: To study the seroepidemiology of pertussis antibodies in a rand om sample of adolescents. Methods: Serum IgG antibodies to whole-cell lysate of Bordetella pertussis were measured by enzyme-linked immunosorbent assay in sera of 533 Israeli m ilitary recruits aged 17-18 years. Epidemiologic variables were collected b y a questionnaire and analyzed for correlation with pertussis antibodies. Results: Of the sera tested 58.6% were positive for pertussis IgG antibodie s, while 35.4% were negative and 6% were borderline. The seropositivity rat e was significantly higher among females and non-smokers than among males a nd smokers. Serum samples of subjects found negative to Bordetella Pertussi s On recruitment were tested again, using the same ELISA assay, 2-3 years l ater. Seroconversion during the 3 year military service was detected in 12. 5% of 40 subjects. Using the pertussis toxin as the antigen in a subsample of 160 sera, the seroprevalence was lower than that detected by the whole-c ell lysate on the same sera (45% vs. 58%). Conclusions: A significant part of the adolescent population in Israel has low titer of serum IgG antibodies to the multiple antigens of B. Pertussis. The relatively low concentration of anti-pertussis antibodies, together wi th the serological evidence of exposure to the disease indicates that boost er immunization with the acellular pertussis vaccine of military recruits s hould be considered after more information on the incidence of clinical cas es of pertussis will be available.