Parapertussis Infection Research Articles

Pertussis Vaccines Scarcely Provide Protection against Bordetella parapertussis Infection in Children-A Systematic Review and Meta-Analysis.

Pertussis, or whooping cough, is a global public health concern. Pertussis vaccines have demonstrated good protection against Bordetella pertussis infections, but their effectiveness against Bordetella parapertussis remains debated due to conflicting study outcomes. A systematic review and meta-analysis were conducted to assess the effectiveness of pertussis vaccines in protecting children against B. parapertussis infection. A comprehensive search of PubMed, Web of Science, and Scopus databases was conducted, and randomized controlled trials (RCTs) and observational studies that met inclusion criteria were included in the analysis. The meta-analysis, involving 46,533 participants, revealed no significant protective effect of pertussis vaccination against B. parapertussis infection (risk ratio: 1.10, 95% confidence interval: 0.83 to 1.44). Subgroup analyses by vaccine type and study design revealed no significant protection. The dearth of recent data and a limited pool of eligible studies, particularly RCTs, underscore a critical gap that warrants future research in the domain. These findings offer crucial insights into the lack of effectiveness of pertussis vaccines against B. parapertussis. Given the rising incidence of cases and outbreaks, coupled with the lack of cross-protection by the existing vaccines, there is an urgent need to develop vaccines that include specific antigens to protect against B. parapertussis.

CLINICAL CASE REPORT: PERTUSSIS INFECTION FOLLOWED BY A PARAPERTUSSIS INFECTION IN THE SAME CHILD

Whooping cough is a vaccine-preventable, acute respiratory disease caused by the gram-negative bacterium Bordetella pertussis. In recent years there has been a worldwide reccurrence of pertussis infection. The most vulnerable group in society are infants under one year of age, they are at the greatest risk of severe complications or even death. Whooping cough is usually associated with infection caused by B. pertussis, but Bordetella parapertussis can also cause pertussis-like symptoms. The disease is known as parapertussisл Clinical data alone are not sufficient to differentiate between the two infections. Modern, fast and reliable diagnostic is .needed. Bordetella holmesii, viral infections caused by RSV, adenovirus, etc. can present with pertussis-like symptoms and should be diagnosed and treated accordingly. The aim of this study is to present a clinical case of a child with pertussis infection followed by parapertussis infection. To diagnose and differentiate the two infections, a real-time PCR molecular genetic method was used to detect the genes specific for the causative agents. Pertussis vaccination does not protect against B. parapertussis infections, and cross-immunity between the two bacteria has not been observed. Therefore, in the presence of pertussis-like symptoms (paroxysms of persistent cough, vomiting after coughing), it is advisable to differentiate between B. pertussis and B.parapertussis infection, especially in populations with high pertussis vaccination coverage.

Adenylate cyclase toxin of Bordetella parapertussis disrupts the epithelial barrier granting the bacterial access to the intracellular space of epithelial cells.

B. parapertussis is one of the etiological agents of whooping cough. Once inhaled, the bacteria bind to the respiratory epithelium and start the infection. Little is known about this first step of host colonization and the role of the human airway epithelial barrier on B. parapertussis infection. We here investigated the outcome of the interaction of B. parapertussis with a polarized monolayer of respiratory epithelial cells. Our results show that B. parapertussis preferentially attaches to the intercellular boundaries, and causes the disruption of the tight junction integrity through the action of adenylate cyclase toxin (CyaA). We further found evidence indicating that this disruption enables the bacterial access to components of the basolateral membrane of epithelial cells to which B. parapertussis efficiently attaches and gains access to the intracellular location, where it can survive and eventually spread back into the extracellular environment. Altogether, these results suggest that the adenylate cyclase toxin enables B. parapertussis to overcome the epithelial barrier and eventually establish a niche of persistence within the respiratory epithelial cells.

DAT (deacylating autotransporter toxin) from Bordetella parapertussis demyristoylates Gαi GTPases and contributes to cough

The pathogenic bacteria Bordetella pertussis and Bordetella parapertussis cause pertussis (whooping cough) and pertussis-like disease, respectively, both of which are characterized by paroxysmal coughing. We previously reported that pertussis toxin (PTx), which inactivates heterotrimeric GTPases of the Gi family through ADP-ribosylation of their α subunits, causes coughing in combination with Vag8 and lipid A in B. pertussis infection. In contrast, the mechanism of cough induced by B. parapertussis, which produces Vag8 and lipopolysaccharide (LPS) containing lipid A, but not PTx, remained to be elucidated. Here, we show that a toxin we named deacylating autotransporter toxin (DAT) of B. parapertussis inactivates heterotrimeric Gi GTPases through demyristoylation of their α subunits and contributes to cough production along with Vag8 and LPS. These results indicate that DAT plays a role in B. parapertussis infection in place of PTx.

Bordetella pertussis, a reemerging pathogen in pediatric respiratory infections. A study in Quito, Ecuador

Bordetella pertussis is the causative agent of pertussis, which mainly affects unvaccinated children, while Bordetella parapertussis causes a disease presenting clinical characteristics that are indistinguishable from whooping cough. Despite high vaccination coverage, pertussis remains a public health concern worldwide, with approximately 140000 cases reported annually. Here we determined the prevalence of B. pertussis and B. parapertussis infection among infants under one year of age by polymerase chain reaction (PCR); our aim being to identify whether the data obtained relates to the relevant sociodemographic and clinical data. The study included 86 samples of nasopharyngeal swabs from infants aged between 0–12 months, who were reported as probable cases of whooping cough by the health centers around the Ecuadorian highlands, from August 2016 to July 2017. The nasopharyngeal swabs were cultured and microbiological and molecular analyses were performed. B. pertussis was identified by PCR in 41% of the samples (30/86), more than half of which corresponded to infants aged between 0–3 months. Moreover, a statistically significant correlation (p<0.05) between the identification of bacteria in culture and the catarrhal stage of the disease was observed. The results obtained from the study highlighted the need for an active national surveillance of pertussis, in particular for laboratory testing, to provide a highly sensitive and more specific diagnosis of Bordetella infection.

Outer-Membrane-Vesicle-Associated O Antigen, a Crucial Component for Protecting Against Bordetella parapertussis Infection.

Bordetella parapertussis is a respiratory-disease pathogen producing symptomatology similar to that of pertussis but of underestimated incidence and with no specific vaccine existing. We recently designed a vaccine candidate from B. parapertussis outer-membrane vesicles (OMVs) that proved to be safe and protective in a murine-infection model. Based on protection recently reported for the B. parapertussis O antigen in aqueous solution, we assessed here whether the B. parapertussis O-antigen-containing lipopolysaccharide (BppLPS-O+) embedded in the membranes, as present in B. parapertussis-derived OMVs (OMVs(Bpp-LPS-O+)), was the component responsible for that previously observed protection by OMVs. By performing a comparative study with OMVs from a human strain with undetectable O antigen (OMVs(Bpp-LPS-O−)), we demonstrated that the OMVs(Bpp-LPS-O+), but not the OMVs(Bpp-LPS-O−), protected mice against sublethal B. parapertussis infections. Indeed, the B. parapertussis loads were significantly reduced in the lungs of OMVs(Bpp-LPS-O+) -vaccinated animals, with the CFUs recovered being decreased by 4 log units below those detected in the non-immunized animals or in the animals treated with the OMVs(Bpp-LPS-O−), (p < 0.001). We detected that the OMVs(Bpp-LPS-O+) induced IgG antibodies against B. parapertussis whole-cell lysates, which immunocomponents recognized, among others, the O antigen and accordingly conferred protection against B. parapertussis infection, as observed in in-vivo–passive-transfer experiments. Of interest was that the OMVs(Bpp-LPS-O+) -generated sera had opsonophagocytic and bactericidal capabilities that were not detected with the OMVs(Bpp-LPS-O−)-induced sera, suggesting that those activities were involved in the clearance of B. parapertussis. Though stimulation of cultured spleen cells from immunized mice with formulations containing the O antigen resulted in gamma interferon (IFN-γ) and interleukin-17 production, spleen cells from OMVs(Bpp-LPS-O+) -immunized mice did not significantly contribute to the observed protection against B. parapertussis infection. The protective capability of the B. parapertussis O antigen was also detected in formulations containing both the OMVs derived from B. pertussis and purified BppLPS-O+. This combined formulation protected mice against B. pertussis along with B. parapertussis.

A recombinant iron transport protein from Bordetella pertussis confers protection against Bordetella parapertussis.

Whooping cough, which is caused by Bordetella pertussis and B. parapertussis, is a reemerging disease. New protective antigens are needed to improve the efficacy of current vaccines against both species. Using proteomic tools, it was here found that B. parapertussis expresses a homolog of AfuA, a previously reported new vaccine candidate against B. pertussis. It was found that this homolog, named AfuABpp , is expressed during B. parapertussis infection, exposed on the surface of the bacteria and recognized by specific antibodies induced by the recombinant AfuA cloned from B. pertussis (rAfuA). Importantly, the presence of the O-antigen, a molecule that has been found to shield surface antigens on B. parapertussis, showed no influence on antibody recognition of AfuABpp on the bacterial surface. The present study further showed that antibodies induced by immunization with the recombinant protein were able to opsonize B. parapertussis and promote bacterial uptake by neutrophils. Finally, it was shown that this antigen confers protection against B. parapertussis infection in a mouse model. Altogether, these results indicate that AfuA is a good vaccine candidate for acellular vaccines protective against both causative agents of whooping cough.

Widespread Bordetella parapertussis Infections-Wisconsin, 2011-2012: Clinical and Epidemiologic Features and Antibiotic Use for Treatment and Prevention.

During October 2011-December 2012, concurrent with a statewide pertussis outbreak, 443 Bordetella parapertussis infections were reported among Wisconsin residents. We examined clinical features of patients with parapertussis and the effect of antibiotic use for treatment and prevention. Patients with polymerase chain reaction results positive for B. parapertussis reported during October 2011-May 2012 were interviewed regarding presence and durations of pertussis-like symptoms and receipt of azithromycin treatment. Data regarding acute cough illnesses and receipt of azithromycin prophylaxis among parapertussis patient household members (HHMs) were also collected. Using multivariate repeated measures log-binomial regression analysis, we examined associations of treatment receipt by the HHM with the earliest illness onset and prophylaxis receipt among other HHMs with the presence of any secondary cough illnesses in the household. Among 218 patients with parapertussis, pertussis-like symptoms were frequently reported. Illness durations were significantly shorter among patients with treatment initiated 0-6 days after cough onset, compared with nonrecipients (median durations: 10 vs 19 days, P = .002). Among 361 HHMs from 120 households, compared with nonrecipients, prompt prophylaxis of HHMs was associated with no secondary cough illnesses (relative risk: 0.16; 95% confidence interval, .04-.69). Bordetella parapertussis infection causes pertussis-like illness that might be misclassified as pertussis if B. parapertussis testing is not performed. Prompt treatment might shorten illness duration, and prompt HHM prophylaxis might prevent secondary illnesses. Further study is needed to evaluate antibiotic effectiveness for preventing parapertussis and to determine risks and benefits of antibiotic use.

Outer membrane vesicles derived from Bordetella parapertussis as an acellular vaccine against Bordetella parapertussis and Bordetella pertussis infection

Bordetella parapertussis, a close related species of B. pertussis, can also cause the disease named pertussis or whooping cough. The number of cases caused by this related pathogen has risen sustained in the last years. The widely used cellular (wP) or acellular (aP) pertussis vaccines have little or no efficacy against B. parapertussis. In an effort to devise an effective acellular vaccine against B. parapertussis infection, outer membrane vesicles (OMVs) were obtained from B. parapertussis. Proteomic analysis of the resulting OMVs, designated OMVsBpp, evidenced the presence of several surface immunogens including pertactin. The characterized OMVsBpp were used in murine B. parapertussis intranasal challenge model to examine their protective capacity when administered by systemic route. Immunized BALB/c mice were challenged with sublethal doses of B. parapertussis. Significant differences between immunized animals and the negative control group were observed (p<0.001). OMVsBpp protected against B. parapertussis infection, whereas current commercial aP vaccine showed little protection against such pathogen. More interestingly, protection induced by OMVsBpp against B. pertussis was comparable to our previously designed vaccine consisting in OMVs derived from B. pertussis (OMVsBp). For these experiments we used as a positive control the current commercial aP vaccine in high dose. As expected aP offered protection against B. pertussis in mice. Altogether the results presented here showed that the OMVs from B. parapertussis are an attractive vaccine candidate to protect against whooping cough induced by B. parapertussis but also by B. pertussis.

Enhancement ofBordetella parapertussisinfection byBordetella pertussisin mixed infection of the respiratory tract

The epidemiological and pathogenic relationship between Bordetella pertussis and Bordetella parapertussis, the two causes of whooping cough (pertussis), is unclear. We hypothesized that B. pertussis, due to its immunosuppressive activities, might enhance B. parapertussis infection when the two species were present in a coinfection of the respiratory tract. The dynamics of this relationship were examined using the mouse intranasal inoculation model. Infection of the mouse respiratory tract by B. parapertussis was not only enhanced by the presence of B. pertussis, but B. parapertussis significantly outcompeted B. pertussis in this model. Staggered inoculation of the two organisms revealed that the advantage for B. parapertussis is established at an early stage of infection. Coadministration of PT enhanced B. parapertussis single infection, but had no effect on mixed infections. Mixed infection with a PT-deficient B. pertussis strain did not enhance B. parapertussis infection. Interestingly, the depletion of airway macrophages reversed the competitive relationship between these two organisms, but the depletion of neutrophils had no effect on mixed infection or B. parapertussis infection. We conclude that B. pertussis, through the action of PT, can enhance a B. parapertussis infection, possibly by an inhibitory effect on innate immunity.

Effectiveness of the whole-cell pertussis vaccine produced in Poland against different Bordetella parapertussis isolates in the mouse intranasal challenge model

The aim of the study was to evaluate the effectiveness of the whole-cell pertussis vaccine produced locally and routinely used in Poland in the elimination of Bordetella parapertussis strains from the lungs and trachea of a mouse model. We found that the average protective effect against B. parapertussis in the lungs of mice immunized with the whole-cell pertussis vaccine (DTwP) was significantly higher than in animals immunized with the acellular pertussis vaccine (DTaP). The effectiveness of B. parapertussis elimination rates from the lungs of DTwP-immunized mice, depending on the strain used as a challenge, was found to be 1.2–3.0 times or 3.1–7.0 times lower than against Bordetella. pertussis Tohama I or vaccine B. pertussis 606/67 isolates, respectively. Our results show that the locally produced DTwP vaccine is able to protect against B. parapertussis isolates; however, the level of protection and course of B. parapertussis infection in the lungs and trachea seems to be strain specific.

T- and B-Cell-Mediated Protection Induced by Novel, Live Attenuated Pertussis Vaccine in Mice. Cross Protection against Parapertussis

BackgroundDespite the extensive use of efficacious vaccines, pertussis still ranks among the major causes of childhood mortality worldwide. Two types of pertussis vaccines are currently available, whole-cell, and the more recent acellular vaccines. Because of reduced reactogenicity and comparable efficacy acellular vaccines progressively replace whole-cell vaccines. However, both types require repeated administrations for optimal efficacy. We have recently developed a live attenuated vaccine candidate, named BPZE1, able to protect infant mice after a single nasal administration.Methodology/Principal FindingsWe determined the protective mechanism of BPZE1-mediated immunity by using passive transfer of T cells and antibodies from BPZE1-immunized mice to SCID mice. Clearance of Bordetella pertussis from the lungs was mediated by both BPZE1-induced antibodies and CD4+, but not by CD8+ T cells. The protective CD4+ T cells comprised IFN-γ-producing and IL-17-producing subsets, indicating that BPZE1 induces both Th1 and Th17 CD4+ T cells. In addition, and in contrast to acellular pertussis vaccines, BPZE1 also cross-protected against Bordetella parapertussis infection, but in this case only the transfer of CD4+ T cells conferred protection. Serum from BPZE1-immunized mice was not able to kill B. parapertussis and did not protect SCID mice against B. parapertussis infection.Conclusions/SignificanceThe novel live attenuated pertussis vaccine BPZE1 protects in a pre-clinical mouse model against B. pertussis challenge by both BPZE1-induced antibodies and CD4+ T cell responses. It also protects against B. parapertussis infection. However, in this case protection is only T cell mediated.

Acellular pertussis vaccination facilitatesBordetella parapertussisinfection in a rodent model of bordetellosis

Despite over 50 years of population-wide vaccination, whooping cough incidence is on the rise. Although Bordetella pertussis is considered the main causative agent of whooping cough in humans, Bordetella parapertussis infections are not uncommon. The widely used acellular whooping cough vaccines (aP) are comprised solely of B. pertussis antigens that hold little or no efficacy against B. parapertussis. Here, we ask how aP vaccination affects competitive interactions between Bordetella species within co-infected rodent hosts and thus the aP-driven strength and direction of in-host selection. We show that aP vaccination helped clear B. pertussis but resulted in an approximately 40-fold increase in B. parapertussis lung colony-forming units (CFUs). Such vaccine-mediated facilitation of B. parapertussis did not arise as a result of competitive release; B. parapertussis CFUs were higher in aP-relative to sham-vaccinated hosts regardless of whether infections were single or mixed. Further, we show that aP vaccination impedes host immunity against B. parapertussis-measured as reduced lung inflammatory and neutrophil responses. Thus, we conclude that aP vaccination interferes with the optimal clearance of B. parapertussis and enhances the performance of this pathogen. Our data raise the possibility that widespread aP vaccination can create hosts more susceptible to B. parapertussis infection.

Dysregulated Macrophage-Inflammatory Protein-2 Expression Drives Illness in Bacterial Superinfection of Influenza

Influenza virus infection is a leading cause of death and disability throughout the world. Influenza-infected hosts are vulnerable to secondary bacterial infection, however, and an ensuing bacterial pneumonia is actually the predominant cause of influenza-attributed deaths during pandemics. A number of mechanisms have been proposed by which influenza may predispose to superinfection with an unrelated or heterologous pathogen, but the subsequent interaction between the host, virus, and bacteria remains an understudied area. In this study, we develop and examine a novel model of heterologous pulmonary infection in which an otherwise subclinical Bordetella parapertussis infection synergizes with an influenza virus infection to yield a life-threatening secondary pneumonia. Despite a profound pulmonary inflammatory response and unaltered viral clearance, bacterial clearance was significantly impaired in heterologously infected mice. No deficits were observed in pulmonary or systemic adaptive immune responses or the viability or function of infiltrating inflammatory cells to explain this phenomenon, and we provide evidence that the onset of severe pulmonary inflammation actually precedes the increased bacterial burden, suggesting that exacerbated inflammation is independent of bacterial burden. To that end, neutralization of the ELR(+) inflammatory chemokine MIP-2 (CXCL2/GRO-beta) attenuated the inflammation, weight loss, and clinical presentation of heterologously infected mice without impacting bacterial burden. These data suggest that pulmonary inflammation, rather than pathogen burden, is the key threat during bacterial superinfection of influenza and that selective chemokine antagonists may be a novel therapeutic intervention in cases of bacterial superinfection of influenza.

Evaluation of 5′-MGB hybridization probes for detection of Bordetella pertussis and Bordetella parapertussis using different real-time PCR instruments

Rapid and accurate tests capable of distinguishing Bordetella pertussis from milder Bordetella parapertussis infection can aid in treating patients. We evaluated a novel real-time polymerase chain reaction (PCR) method that allows rapid and accurate diagnosis and distinction between B. pertussis and B. parapertussis infections. The method is based on a fluorescent 5′-minor groove-binding molecule hybridization probe that can clearly distinguish between B. pertussis and B. parapertussis by post-PCR melt curve analysis. The reagents worked equally well in several different real-time PCR instruments. The Bordetella detection reagents are combined with internal control components to account for PCR inhibition without compromising assay sensitivity.

Live Attenuated B. pertussis as a Single-Dose Nasal Vaccine against Whooping Cough

Pertussis is still among the principal causes of death worldwide, and its incidence is increasing even in countries with high vaccine coverage. Although all age groups are susceptible, it is most severe in infants too young to be protected by currently available vaccines. To induce strong protective immunity in neonates, we have developed BPZE1, a live attenuated Bordetella pertussis strain to be given as a single-dose nasal vaccine in early life. BPZE1 was developed by the genetic inactivation or removal of three major toxins. In mice, BPZE1 was highly attenuated, yet able to colonize the respiratory tract and to induce strong protective immunity after a single nasal administration. Protection against B. pertussis was comparable to that induced by two injections of acellular vaccine (aPV) in adult mice, but was significantly better than two administrations of aPV in infant mice. Moreover, BPZE1 protected against Bordetella parapertussis infection, whereas aPV did not. BPZE1 is thus an attractive vaccine candidate to protect against whooping cough by nasal, needle-free administration early in life, possibly at birth.

Epidemiology and characterization of Bordetella parapertussis strains isolated between 1995 and 2002 in and around Warsaw, Poland

The aim of the study presented here was to analyze parapertussis infections occurring in the region of Warsaw, Poland, between 1995 and 2002 and to characterize the Bordetella parapertussis isolates using macrorestriction digestion of genomic DNA. Fourteen of the 17 patients with confirmed Bordetella parapertussis infection were between the ages of 5 and 9 years, and 14 had documented vaccination with the diphtheria-tetanus-pertussis whole-cell vaccine; for the remaining three patients vaccination data was not available. DNA fingerprinting performed using recommended standard methodology revealed a close relationship between the examined strains and reference strain ATCC 9305, thus confirming the conservative nature of Bordetella parapertussis.

Immunologic and epidemiologic experience of vaccination with a monocomponent pertussis toxoid vaccine.

Pertussis re-emerged in Sweden with a cumulative incidence of about 60% during the first 10 years of life, when the locally produced cellular vaccine lost its efficacy around 1970 and general vaccination was discontinued in 1979. The epidemiology, clinical features, and immunology of pertussis and a monocomponent pertussis toxoid vaccine were studied in Göteborg, Sweden. After phase 1 and 2 studies, a randomized, double-blind, placebo-controlled trial of pertussis toxoid (PTox), compounded with diphtheria and tetanus toxoids, was administered to 3450 children according to the Swedish schedule at 3, 5, and 12 months of age. After a mean follow-up of 18 months, the efficacy was 71% overall and 75% in household contacts, respectively. A statistically significant correlation was found between the level of PTox-induced antibodies and protection against pertussis. As observed with cellular and with multicomponent acellular vaccines, PTox reduced the severity of disease and the percent of children with positive cultures. Furthermore, vaccination reduced the transmission of Bordetella pertussis to household contacts in the vaccinees compared with the controls who received only diphtheria and tetanus toxoids. Patients with culture-verified Bordetella parapertussis infection reacted with antibodies to pertactin and to filamentous hemagglutinin but not to pertussis toxin, and some subsequently developed pertussis. The antibody responses of patients with pertussis to the surface polysaccharides of B pertussis and to B parapertussis were cross-reactive serologically. Serosurveys showed that only antibodies to pertussis toxin were related to the occurrence of pertussis in the general population: antibodies to filamentous hemagglutinin and pertactin were probably stimulated by antigens of other bacteria as well as Bordetellae. Mass vaccination of Göteborg children born in the 1990s was started in 1995. In February 1999, about 55% had been vaccinated and both B pertussis and pertussis decreased significantly in individuals of all ages (herd immunity). Similar to diphtheria, PTox-induced immunity to pertussis occurs both on an individual and community basis. The apparent greater efficacy of multicomponent acellular pertussis vaccines compared with monocomponent PTox was proposed to be an artifact created when the diagnosis of pertussis was made by the serologic criteria of the World Health Organization only. Our conclusion is that PTox is both an essential and alone sufficient antigen in acellular pertussis vaccines.

Outbreak of pertussis in Basra, Iraq

A total of 133 pertussis cases were studied during an outbreak in Basra from June to December 1996. Most were females and were immunized. Bordetella spp. was isolated in 48.1% of the cases. The isolation rate was highest among infants and decreased with increasing age, and was highest during the catarrhal stage. B. pertussis was the most common species; however, B. parapertussis infection did occur. There were some severe cases of pertussis among infants caused mainly by B. pertussis and dual Bordetella infection. Infection was transmitted by close contact with a pertussis case.

Whooping cough caused by Bordetella pertussis and Bordetella parapertussis in an immunized population.

The prevalence of Bordetella pertussis and Bordetella parapertussis infections among outpatients in an immunized population is not known. To study the prevalence of these infections in outpatients with paroxysmal cough in Finland, where the pertussis vaccine coverage of 4 doses is 98%. Prospective cohort study. Thirty-two health centers in southwestern Finland. A total of 584 patients with paroxysmal cough seen at local health centers from October 1994 through March 1997 from whom nasopharyngeal swabs were collected. Prevalence of positive cultures for B pertussis or B parapertussis and/or positive polymerase chain reaction (PCR) results and frequency of symptoms in those with pertussis and parapertussis. A total of 153 subjects (26.2%) had Bordetella infection by culture or PCR: 93 (60.8%) had B pertussis infection, 49 (32.0%) had B parapertussis infection, and 1 1 (7.2%) had both. Of these cases, 39 (25.5%) had positive cultures and 95 (62.1%) had positive PCR results for B pertussis, and 19 (12.4%) had positive cultures and 55 (35.9%) had positive PCR results for B parapertussis. At the time of diagnosis, no difference was found in the frequency of symptoms between patients with B parapertussis infection and those with B pertussis infection. Bordetella parapertussis infection was as common as B pertussis infection in children before school entry, whereas in schoolchildren and adults, B pertussis infection was more common than B parapertussis infection (P<.001). Bordetella infections are common in an immunized population, and B parapertussis infections apparently are more prevalent than previously documented.