Pertussis

Pertussis (whooping cough) is caused by Bordetella pertussis, a gram-negative bacterium. It progresses through three distinct phases. Catarrhal phase (1–2 weeks): resembles a common cold with rhinorrhea, mild cough, low-grade fever. This is the MOST contagious phase and the one most often missed. Paroxysmal phase (2–6 weeks or longer): severe coughing fits (paroxysms) followed by a forceful inspiratory 'whoop,' post-tussive vomiting, and cyanosis. Between paroxysms the patient may appear well. Convalescent phase (weeks to months): gradual resolution of cough frequency and severity. Critical age-related distinction: infants under 6 months — especially those too young for vaccination — may NOT produce the characteristic whoop. Instead, they present with apnea, cyanosis, and difficulty feeding. Pertussis is a leading cause of vaccine-preventable infant death. Diagnosis: nasopharyngeal swab for PCR (preferred) or culture (gold standard but slow). Treatment: azithromycin is first-line, including for young infants (monitor for infantile hypertrophic pyloric stenosis risk in neonates). Erythromycin or clarithromycin are alternatives in some patients. TMP-SMX is an alternative only for patients ≥2 months who cannot take macrolides — it is avoided in younger infants due to kernicterus risk. Antibiotics reduce transmission but do NOT significantly shorten illness duration if started after the paroxysmal phase begins. Droplet precautions until 5 days of appropriate antibiotics are completed. Prevention — the most tested content area: DTaP vaccine for children (5-dose series). Tdap for adolescents and adults. Tdap in EVERY pregnancy at 27–36 weeks gestation regardless of previous Tdap history — this transfers maternal antibodies to the newborn, providing passive protection during the most vulnerable period before the infant's own vaccination can begin at 2 months. Cocooning strategy: vaccinate all household contacts and caregivers of newborns. Pertussis is a nationally notifiable disease. Nursing: suction equipment at bedside, small frequent meals to reduce post-tussive vomiting, monitor infant oxygen saturation during and between paroxysms, provide calm quiet environment (agitation worsens coughing), and educate families that cough may persist for months during convalescence.