parapertussis

Parapertussis is a contagious respiratory infection caused by Bordetella parapertussis, a close relative of Bordetella pertussis. It causes a mild, pertussis-like illness characterized by a persistent cough, usually less severe than classic whooping cough. Infants can be affected, but illness is often milder in older children and adults.

Clinical features include a persistent cough lasting more than one to two weeks, nasal congestion, and malaise. Paroxysmal coughing and vomiting are less common than in pertussis. Fever is usually low-grade or absent. The overall course is often self-limited over several weeks.

Diagnosis relies on laboratory tests to distinguish parapertussis from pertussis. PCR testing of nasopharyngeal samples or culture on Bordet-Gengou or Regan-Lowe selective media can identify Bordetella parapertussis. Clinical presentation alone is insufficient for reliable differentiation.

Transmission occurs via respiratory droplets; the pattern is similar to other pertussis group infections. It is found worldwide, with seasonal variation mirroring pertussis. Because symptoms are often milder, parapertussis may be underdiagnosed.

Treatment consists of macrolide antibiotics (eg, azithromycin, clarithromycin, erythromycin). Antibiotics are most effective when started early to reduce transmission; they may not markedly shorten established cough. There is no vaccine specifically for parapertussis; standard pertussis vaccines do not reliably prevent parapertussis.