The past, present, and future of pertussis. The role of adults in epidemiology and future control.

Pertussis is a severe epidemic disease that causes significant morbidity and mortality in unimmunized children. It is now clear, however, that adults with atypical disease account for many of the cases and are often responsible for transmission to susceptible infants. Because of the extent of unrecognized pertussis in the adult population, mass pediatric immunization has been successful in controlling the disease in children but not in reducing the presence of the organism in the United States. Pertussis immunization of children is associated with a high rate of side reactions and is temporally related to severe neurologic disease and death in infants. These events are often considered to be reactions, but available scientific evidence indicates that few, if any, are actually caused by pertussis immunization. Pertussis vaccine reactogenicity in adults is anecdotally considered to be worse than in children, but direct studies do not support that. In the context of current programs emphasizing adult immunization, consideration should be given to booster doses of diphtheria-tetanus-pertussis in adults, using component pertussis vaccines when they become available.