Parapertussis: A New Look at An Overlooked Disease

Background: Whooping cough is caused by Bordetella pertussis and Bordetella parapertussis.  Availability of polymerase chain reaction (PCR) testing and primers to differentiate between Bordetella spp. have resulted in increased confirmation of parapertussis cases.  Currently, national guidelines for prevention and control of parapertussis are not available and are needed to facilitate decision-making when potential cases or outbreaks are identified.

Objectives: To propose evidence-based recommendations for the prevention and control of whooping cough caused by B. parapertussis.

Methods: Articles from 1940 to 2009, published in English and available through scientific databases, were systematically reviewed for data concerning clinical presentation, transmission, virulence, vaccine efficacy, epidemiology, laboratory diagnosis, treatment and chemoprophylaxis.  State public health departments were contacted to identify existing guidelines.

Results: The clinical presentation of illness caused by the two species are similar; parapertussis is documented to be milder and of shorter duration, although severe disease and death have been reported.   Although insufficient data remains about appropriate antibiotic use for parapertussis, erythromycin has been offered as a treatment option.  Similar to pertussis, parapertussis is highly contagious, spreads through inhaled respiratory aerosols, and affects all age groups.  Studies evaluating the prevalence of B. parapertussis provide inconsistent results making it difficult to assess the true burden of disease.  Additionally, parapertussis is not a reportable disease and the epidemiology in the U.S. remains uncertain.  Although both organisms share some antigenic components, B. parapertussis does not produce pertussis toxin and pertussis vaccines have not been shown to provide significant protection against parapertussis.  Clinical accuracy and ability to differentiate between the two species vary greatly by testing method and laboratories. 

Conclusions: This presentation will provide an overview of available evidence for parapertussis and propose draft recommendations for feedback that focus on preventing transmission to infants at increased risk of severe disease and death.  Final recommendations will be included in CDC’s revised pertussis outbreak response guidelines.