The disease still carries significant morbidity and mortality in infants younger than 2 years. Pertussis should be included in the differential diagnosis of protracted cough with cyanosis or vomiting, persistent rhinorrhea, and marked lymphocytosis. Bordetella pertussis is an aerobic, nonmotile, gram-negative coccobacillus that attaches to and multiplies on the respiratory epithelium, starting initially in the nasopharynx and ending up, primarily, in the bronchi and bronchioles. A mucopurulosanguinous exudate is formed in the respiratory tract.
Most cases occur in the late summer and early fall.
This decreased to a low in 1976, when there were 1010 cases and only 4 deaths. Pertussis is the most commonly reported vaccine-preventable disease in the US among children younger than 5 years. This has resulted in more than 10,000 cases being reported in the 1970s and 1980s, with more than 200 deaths and 10,000 prolonged hospitalizations. Germany had a similar occurrence in the 1980s and 1990s. This approaches the incidence in the prevaccination era.