Pertussis: Challenges Today and for the Future

Pertussis is a truly unique contagious respiratory disease [1–4]. It is mainly caused by Bordetella pertussis, but similar cough illnesses can be caused by B. parapertussis in young children and B. holmesii in adolescents and adults. (The remainder of this communication will be restricted to B. pertussis infection and illness.) Illness due to B. pertussis has a number of characteristics that differentiate it from all other severe respiratory illnesses [1–4]. The basic illness is noninflammatory in nature and occurs without significant fever. Mortality is greater in girls than in boys. The characteristic, nonproductive paroxysmal cough followed by periods of total respiratory normalcy is different from all other infectious cough illnesses. Concomitant respiratory viral infections and secondary bacterial infections that include fever and other manifestations of inflammation have over the years led to confusion as to the fundamental illness caused by B. pertussis. Neither B. pertussis infection or pertussis vaccination elicit longlasting immunity [1,4]. Infection and illness repeatedly occur in all ages throughout life. In the prevaccine era, pertussis morbidity and mortality was staggering. Vaccines (killed whole organisms—DTwP) were developed in the 1930s, and their subsequent use beginning in the late 1940s resulted in a 157-fold decrease in the pertussis attack rate [1,4]. Because DTwP vaccines contained endotoxin, their use was associated with considerable side effects. Technology of the 1970s and 1980s enabled the production of acellular vaccines (DTaP) that were less reactogenic because of the removal of endotoxin. These DTaP vaccines only contained a small number of antigens in comparison with DTwP vaccines. DTaP vaccines were put into universal use in the United States in the late 1990s.