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Pertussis is a highly communicable, vaccine-preventable, respiratory illness caused by the bacterium Bordetella pertussis. It is typically characterized by paroxysms of severe coughing that can last for many weeks and are often associated with inspiratory whooping and posttussive vomiting. In the prevaccine era, pertussis was a significant cause of morbidity and mortality among infants and children in the United States.1 With introduction of pertussis vaccines in the 1940s, the number of reported cases declined substantially; however, in more recent years, a resurgence of disease has been observed (Fig. 97-1).1–4
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Pertussis is an endemic disease worldwide. The disease is cyclic in nature, with epidemic cycles typically occurring every 2–5 years. While differences in surveillance methodology, vaccination schedules, and diagnostic capacity make accurate estimates of disease burden across countries challenging, data from a recent modeling study suggest that more than 24 million new pertussis cases occurred globally among children less than 5 years of age in 2014, and caused an estimated 160,700 deaths.5
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Before pertussis vaccine introduction in the United States in the late 1940s, an average of 200,000 cases and 4000 pertussis-related deaths were reported each year.1 However, following the introduction of pertussis vaccines, a > 99% reduction in reported pertussis was observed, highlighting the success of the vaccination program. Although reported cases reached a nadir of approximately 1000 cases in 1976, case counts have gradually increased since the late 1980s (Fig. 97-1). A recent analysis of U.S. national surveillance data showed that the average annual incidence of pertussis increased significantly between 2000 and 2016, with notable cyclicity in disease, ranging from a low of 2.7/100,000 in 2001, to a high of 15.4/100,000 in 2012.4 Numerous factors are thought to be contributing to this observed increase, including changes in diagnostic testing and reporting, increased provider recognition, and molecular changes in the B. pertussis organism.6,7 However, recent data support waning of vaccine-induced immunity as an important cause of the increase in the United States as well as in other countries that have transitioned from whole cell to acellular pertussis vaccine formulations.8–12
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In the United States, the incidence of pertussis is highest in infants too young to have received adequate vaccination (i.e., at least three doses), although incidence among school-aged children and adolescents has been increasing (Fig. 97-2). Evaluation of U.S. national surveillance data revealed an increase in disease among 7–10 years olds during the late 2000s and then later among adolescents, groups thought to be well-protected by pertussis vaccines. Increases in reported disease in these age groups coincided with the aging of ...