The etiologic agent of whooping cough is

• A. Bordetella pertussis
• B. Brucella suis
• C. Francisella tularensis
• D. Haemophilus ducreyi

Answer: (A)

Whooping cough is caused by Bordetella pertussis, a small Gram-negative coccobacillus that colonizes the respiratory tract and releases toxins that disrupt the normal function of ciliated airway cells. The illness classically progresses from a mild catarrhal phase to a paroxysmal coughing stage, sometimes with an inspiratory whoop, and can be especially severe in young children. Diagnosis is supported by culture on Bordet-Gengou (or Regan-Lowe) medium and by PCR; vaccination with DTaP in childhood and Tdap boosters for adolescents and adults helps prevent disease. The other organisms listed cause entirely different diseases: Brucella suis leads to brucellosis, Francisella tularensis to tularemia, and Haemophilus ducreyi to chancroid.