PREVALENCE AND INCIDENCE OF ADULT PERTUSSIS IN AN URBAN-POPULATION

Objectives.-To determine the prevalence of Bordetella pertussis infect ion among adults who have prolonged cough for 2 weeks or longer and to estimate the incidence of B pertussis infection in adults in a define d urban population. Design.-A prospective clinical study. Setting.-Kai ser Permanente, San Francisco (Calif) Medical Center. Participants.-On e hundred fifty-three referred and participating health plan members 1 8 years old or older with the complaint of cough:persisting for 2 week s or longer and 154 health plan members 18 years old or older with no cough for the past 3 months (controls) were enrolled. Medical records for an additional 100 patients randomly sampled from 676 patients 18 y ears old or older with an ambulatory diagnosis of cough (60 with prolo nged cough) were also reviewed. Main Outcome Measures.-Prevalence of a dult pertussis as determined by enzyme-linked immunosorbent assay IgG antibody levers to pertussis toxin in individuals with prolonged cough for 2 weeks or longer and the incidence of adult pertussis in San Fra ncisco Kaiser health plan members. Results.-The prevalence of adult pe rtussis was 12.4% of the participating referrals. The incidence of adu lt pertussis was estimated to be 176 cases per 100 000 person-years (9 5% confidence interval, 97 to 255 cases). Conclusions.-Adult pertussis is a significantly greater public health threat than previously suspe cted, Booster doses of acellular pertussis vaccine after 7 years of ag e may bean effective approach to minimize transmission and infection.