A significant number present with cyanosis and apneic spells. Vaccinated adults usually only develop a prolonged bronchitis without a whoop. Unvaccinated adults are more likely to have whooping and posttussive emesis. On average, they wait a median of 3 weeks before seeking treatment. Hypoxia should be considered.
Dehydration is common on presentation.
Mild fever is common. Fever over 39 C is rare. B pertussis Bordetella parapertussis and Bordetella bronchiseptica are less common and produce a similar but milder clinical illness. In adults, especially those vaccinated, lymphocytosis is rare. Definitive culture diagnosis is not always possible.