pertusis

Pertussis, or whooping cough, is a highly contagious respiratory infection caused by the bacterium Bordetella pertussis. It spreads through respiratory droplets and close contact. The incubation period is typically 7 to 10 days, though it can be longer.

Clinical course often proceeds through stages: catarrhal, paroxysmal, and convalescent. The catarrhal stage presents with a mild upper respiratory illness, runny nose, and low-grade fever for 1–2 weeks. The paroxysmal stage features rapid, forceful coughing fits followed by a distinctive inspiratory whoop; vomiting and extreme fatigue can occur. Infants may have little or no whoop and may experience apnea or cyanosis. Recovery is gradual and can take several weeks to months.

Diagnosis relies on clinical suspicion supported by laboratory testing. PCR from nasopharyngeal swabs or nasal aspirates is commonly used and most sensitive early in illness. Culture is specific but slower and less sensitive. Serology may assist in later stages or outbreak investigations. Differential diagnosis includes other viral and bacterial respiratory infections.

Treatment primarily involves appropriate antibiotics, with macrolides such as azithromycin, clarithromycin, or erythromycin used to reduce transmission and may lessen illness duration if started early. Alternatives include trimethoprim-sulfamethoxazole for macrolide allergies. Supportive care is important, particularly for infants who are at higher risk of complications.

Prevention is achieved through vaccination with diphtheria, tetanus, and acellular pertussis (DTaP in childhood; Tdap for adolescents and adults). Vaccination reduces severity and transmission, but immunity wanes over time, necessitating boosters. Public health measures emphasize vaccination coverage and outbreak control in unvaccinated or under-vaccinated populations.