Since 2004, more than 25,000 cases of pertussis have been reported in the United States each year. Symptoms in adults range from mild cough to severe persistent cough with posttussive emesis. The characteristic paroxysmal cough (whoop) may be absent, and the diagnosis is often missed, especially when the cough is mild. The most useful diagnostic test to confirm pertussis is a polymerase chain reaction assay of a nasopharyngeal swab sample. Patients are infectious for three weeks from the cough onset. Antibiotic treatment, preferably with macrolide antibiotics, is indicated during this time for pertussis treatment and prophylaxis. In 2005, two new acellular pertussis vaccines were licensed: one (Boostrix) for patients aged 10 to 18 years and another (Adacel) for patients aged 11 to 64 years.