Bordetella parapertussis Re-emerges as a Cause of Respiratory Illness in Children

Kristina A. Bryant, MD


June 22, 2023

A 4-year-old male presented to an urgent care center with a 2-week history of runny nose and cough. The treating clinician suspected a postviral cough, but the child’s mother was unconvinced. Testing for SARS-CoV-2, influenza, and respiratory syncytial virus performed earlier in the week at the pediatrician’s office was negative. At the mother’s insistence, an expanded respiratory panel was ordered and revealed a surprising result: Bordetella parapertussis.

Just like B. pertussis, B. parapertussis can cause a prolonged cough illness characterized by coughing paroxysms, whoop, and posttussive emesis. Testing is the only way to reliably distinguish between the two infections. In general, disease due to B. parapertussis tends to be milder than typical pertussis and symptoms usually don’t last as long. In one study, 40% of people with B. parapertussis had no symptoms. B. parapertussis does not produce pertussis toxin and this may affect disease severity. Rarely, children can be coinfected with both B. pertussis and B. parapertussis.

Kristina A. Bryant, MD

The burden of B. parapertussis in the United States is not well described because only pertussis cases caused by B. pertussis are reportable to the Centers for Disease Control and Prevention. Nevertheless, some states include cases in public reporting and outbreaks have been reported. Historically, disease has been cyclical, with peaks in cases every 4 years and no seasonality.

This year, some communities are currently seeing an increase in B. parapertussis cases. Through June 11 of this year, 40 cases of B. parapertussis and no cases of B. pertussis have been identified at Norton Healthcare in Louisville, Ky. For comparison, one case of B. parapertussis was reported in 2022 and no cases were reported in 2021. Chatter on infectious diseases listservs suggests that clinicians in other communities are also seeing an increase in cases.

According to Andi Shane, MD, MPH, chief of the division of pediatric infectious diseases at Emory University and Children’s Healthcare of Atlanta, an unusually high number of children with B. parapertussis were identified in the Atlanta area this spring. “Fortunately, most children had mild illness and of these, only a few required admission to the hospital,” Dr. Shane said.

Back at the urgent care center, the clinician on duty called the patient’s mom to discuss the diagnosis of B. parapertussis. By the time the test result was available, the patient was asymptomatic. The clinician advised that antibiotic therapy was not indicated.

Treatment recommendations diverge for B. pertussis and B. parapertussis and this is a point of emphasis for clinicians. Treatment of B. pertussis during the catarrhal phase may ameliorate disease. Treatment initiated after the catarrhal phase has little impact on symptoms but may reduce spread to others. In most cases, treatment isn’t recommended for B. parapertussis. It is not clear how well antibiotics work against this organism. Macrolides such as erythromycin and azithromycin that are used to treat pertussis may have some activity, along with trimethoprim-sulfamethoxazole and ciprofloxacin. According to the American Academy of Pediatrics, treatment is usually reserved for individuals at risk for more severe disease, including infants, especially those less than 6 months of age, the elderly, and immunocompromised persons. Prophylactic antibiotic therapy is not recommended for most persons exposed to B. parapertussis, although some public health experts also recommend treatment of B. parapertussis-infected people in contact with young infants and others are risk for severe disease.

In recent epidemiologic reports, patients with B. parapertussis infection had received age-appropriate vaccination for pertussis, suggesting that available pertussis vaccines offer little to no protection against this disease. The best prevention strategies are similar to those that are effective against other illness spread by respiratory droplets. Sick people should stay at home and cover their coughs when around others. Everyone should practice good hand hygiene.

Are you seeing increased cases of B. parapertussis in your community? Email me at

Dr. Bryant is a pediatrician specializing in infectious diseases at the University of Louisville (Ky.) and Norton Children’s Hospital, also in Louisville. She is a member of the AAP’s Committee on Infectious Diseases and one of the lead authors of the AAP’s Recommendations for Prevention and Control of Influenza in Children, 2022-2023. The opinions expressed in this article are her own. Dr. Bryant discloses that she has served as an investigator on clinical trials funded by Pfizer, Enanta and Gilead. Email her at

This article originally appeared on, part of the Medscape Professional Network.

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