OUTBREAK OF PERTUSSIS IN A FULLY IMMUNIZED ADOLESCENT AND ADULT-POPULATION

Objective: To evaluate the spread of pertussis in a fully immunized eighth-grade class and the household contacts of two coindex cases of pertussis. Design: Survey of infected subjects and their contacts was performed using culture, direct fluorescent antibody assay, and serological assays to establish the diagnosis of Bordetella pertussis. Setting: Middle-class parochial school. Participants: A volunteer sample of 15 eighth-grade students and 13 household contacts of two identified cases of B pertussis infection. Interventions: All participants had medical histories (including immunization status) and laboratory evaluation for B pertussis infection (including nasopharyngeal specimens and serum samples) obtained initially and 30 days later. After initial evaluation, all subjects received erythromycin ethyl succinate therapy. Main Outcome Measures: Assessment of B pertussis infection as defined by positive nasopharyngeal culture, direct fluorescent antibody, or serological tests. Results: Laboratory evidence of B pertussis infection was found in eight (47%) of 17 immunized eighth-grade classmates and in three (23%) of 13 household contacts, all of whom were 12 years of age or older. Conclusions: Vaccine-induced immunity wanes by early adolescence. These older age groups may be infected with B pertussis and may serve as reservoirs of infection for other susceptible individuals.