Seroepidemiology of pertussis in the Japanese population.

To ascertain just how widely Bordetella pertussis infection occurs in Japan, we assessed the immune level against pertussis in various age-groups in the Japanese population. Using sera mainly obtained from 6- to 75-year old subjects who visited the Tokyo Metropolitan Komagome Hospital, we determined the levels of bacterial agglutinins to Bordetella pertussis, of anti-filamentous hemagglutinin and of anti-pertussis toxin. The bacterial agglutinin titers in the older age-groups seemed to be slightly lower than those in the younger age-groups, but no obvious differences between the older and the younger age-groups were found in the levels of anti-filamentous hemagglutinin and anti-pertussis toxin. The older subjects were assumed to acquire these antibodies through clinical or subclinical natural pertussis infections because, prior to 1951, mass vaccination against pertussis was not practice in Japan. Our results reasonably indicate that Bordetella pertussis widely infests Japan, so that vaccination is inevitably warranted to prevent pertussis epidemics and to lower the pertussis case rates.