Parapertussis: Pertussis, but Not Quite

Column Author and Editor: Chris Day, MD | Pediatric Infectious Diseases; Director, Transplant Infectious Disease Services; Medical Director, Travel Medicine; Assistant Professor of Pediatrics, University of Missouri-Kansas City School of Medicine; Clinical Assistant Professor of Pediatrics, University of Kansas School of Medicine

Bordetella parapertussis was recently detected from clinical specimens submitted to the microbiology laboratory at Children’s Mercy Kansas City. Unlike many respiratory infections, summer infections with Bordetella parapertussis may be more common than infections in other seasons. This seems to be true of Bordetella pertussis as well, with increases in infection often seen in the summer or fall, although with both infections, some amount of illness can and does occur throughout the year.^1-3 

Bordetella parapertussis is one of four species of Bordetella known to cause infection in humans: B. pertussis, of course, is the classical cause of pertussis. B. bronchiseptica is a cause of infectious tracheobronchitis (“kennel cough”: it is the pathogen targeted by the canine vaccine) in dogs and other mammals. It is sometimes a cause of respiratory infection in immunocompromised human hosts. B. holmesii has also been found in immunocompromised hosts, including cases of bacteremia, and appears to cause pertussis-like illness sometimes in healthy hosts.⁴ 

The illness caused by B. parapertussis is similar to classical whooping cough. Cough (including coughing paroxysms), whooping, vomiting, apnea and cyanosis all occur, depending on the age of the patient. The average duration of symptoms is significantly shorter than with B. pertussis, with one study showing a mean of 21 days of cough (25% did have 30 or more days of cough and 19 or more days of paroxysms) compared to two to three times as long in children of the same age with pertussis.¹ In true pertussis, the pertussis toxin itself is thought to cause the observed lymphocytosis; in B. parapertussis infection, no lymphocytosis or leukocytosis is usually observed.⁵  

Laboratory diagnosis is typically made in the process of looking for B. pertussis or for other respiratory pathogens. An order for a specific PCR for B. pertussis typically will include a PCR test for B. parapertussis. Multiplex PCR testing for respiratory pathogens that tests for B. pertussis will usually have a test for B. parapertussis as well. As with B. pertussis, false negatives can occur related to inadequate sampling, and tests will also be negative if obtained too long (probably more than around three weeks) after cough onset. B. parapertussis can also be grown on culture: cultures are most helpful when obtained within two weeks of cough onset.⁶ While there are ways to serologically distinguish B. parapertussis infection from B. pertussis infection, it does not appear that there is any B. parapertussis serology available commercially. 

Pertussis vaccines do not appear to provide much if any protection against B. parapertussis infection or to shorten symptoms of the infection. Erythromycin, azithromycin, clarithromycin, TMP-SMX and ciprofloxacin have activity against B. parapertussis although, based on the data we have, it is generally less susceptible to antibiotics. Antibiotic therapy early in the course may be useful to prevent the development of more severe disease and to shorten the course of illness, particularly in infants, the elderly and immunocompromised people. There are no recommendations for chemoprophylaxis for individuals exposed to infection.⁷ 

References: 

1. Mastrantonio P, Stefanelli P, Giuliano M, et al. Bordetella parapertussis infection in children: epidemiology, clinical symptoms, and molecular characteristics of isolates. J Clin Microbiol. 1998;36(4):999-1002. doi: 10.1128/JCM.36.4.999-1002.1998  
2. Bhatti MM, Rucinski SL, Schwab JJ, Cole NC, Gebrehiwot SA, Patel R. Eight-year review of Bordetella pertussis testing reveals seasonal pattern in the United States. J Pediatric Infect Dis Soc. 2017;6(1):91-93. doi:10.1093/jpids/piv079 
3. Hitz DA, Tewald F, Eggers M. Seasonal Bordetella pertussis pattern in the period from 2008 to 2018 in Germany. BMC Infect Dis. 2020;20(1):474. doi:10.1186/s12879-020-05199-w 
4. McIntyre PB, Sintchenko V. The “how” of polymerase chain reaction testing for Bordetella pertussis depends on the “why.” Clin Infect Dis. 2013;56(3):332-334. doi:10.1093/cid/cis897 
5. Heininger U, Stehr K, Schmitt-Grohé S, et al. Clinical characteristics of illness caused by Bordetella parapertussis compared with illness caused by Bordetella pertussis. Pediatr Infect Dis J. 1994;13(4):306-309. PMID: 8036048. doi:10.1097/00006454-199404000-00011 
6. National Center for Immunization and Respiratory Diseases. Manual for the surveillance of vaccine-preventable diseases. Chapter 10: pertussis. Last reviewed May 11, 2020. Accessed June 8, 2023. https://www.cdc.gov/vaccines/pubs/surv-manual/chpt10-pertussis.html 
7. Pertussis (whooping cough). In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH., eds. Red Book: 2021-2024 Report of the Committee on Infectious Diseases. 32nd ed. American Academy of Pediatrics; 2021.