Bordetella pertussis and concomitant viral respiratory tract infections are rare in children with cough illness

BACKGROUND: Case reports, case series, and retrospective and prospective studies have reported concomitant Bordetella pertussis and viral respiratory tract pathogen infections in children with cough illness with conflicting results regarding their frequency. METHOD: A prospective 1-year study was performed in ambulatory and hospitalized patients aged 0 to 17 years with a cough illness. Polymerase chain reaction for viral (influenza A and B, parainfluenza 1 and 3, respiratory syncytial, metapneumovirus, and adenovirus) and bacterial pathogens including B. pertussis and B. parapertussis was applied to nasopharyngeal aspirate (NPA) specimens. The primary goal of the study was to assess the frequency of unsuspected Bordetella infections in patients thought to have a viral respiratory tract infection. The secondary goal was to determine the frequency of concomitant viral respiratory tract and Bordetella infections. RESULTS: B. pertussis and B. parapertussis DNA was amplified in 21 (2.0%) and 5 (0.5%) cases, respectively, of 1059 NPA specimens. Of the 1059 NPA specimens, 877 were tested in parallel for respiratory viruses, B. pertussis, and B. parapertussis; <1 virus was identified in 427 (48.7%) and Bordetella species was identified in 10 (1.1%) of these 877 NPA specimens but only 2 (0.2%) concomitant virus/Bordetella infections were identified. Specifically, of 268 NPAs positive for RSV, 1 (0.37%) was concomitant with B. pertussis infection as was 1 (3.7%) of 27 NPAs positive for hMPV. CONCLUSIONS:: B. pertussis and B. parapertussis infections were rare in patients with cough illness and so were concomitant virus/Bordetella infections. We propose that virus/Bordetella coinfections primarily occur by chance.