Systemic priming and intranasal booster with a BcfA-adjuvanted acellular pertussis vaccine generates CD4+ IL-17+ nasal tissue resident T cells and reduces B. pertussis nasal colonization

Introduction

Resurgence of pertussis, caused by Bordetella pertussis, necessitates novel vaccines and vaccination strategies to combat this disease. Alum-adjuvanted acellular pertussis vaccines (aPV) delivered intramuscularly reduce bacterial numbers in the lungs of immunized animals and humans, but do not reduce nasal colonization. Thus, aPV-immunized individuals are sources of community transmission. We showed previously that modification of a commercial aPV (Boostrix) by addition of the Th1/17 polarizing adjuvant Bordetella Colonization Factor A (BcfA) attenuated Th2 responses elicited by alum and accelerated clearance of B. pertussis from mouse lungs. Here we tested whether a heterologous immunization strategy with systemic priming and mucosal booster (prime-pull) would reduce nasal colonization.

Methods

Adult male and female mice were immunized intramuscularly (i.m.) with aPV or aPV/BcfA and boosted either i.m. or intranasally (i.n.) with the same formulation. Tissue-resident memory (TRM) responses in the respiratory tract were quantified by flow cytometry, and mucosal and systemic antibodies were quantified by ELISA. Immunized and naïve mice were challenged i.n. with Bordetella pertussis and bacterial load in the nose and lungs enumerated at days 1-14 post-challenge.

Results

We show that prime-pull immunization with Boostrix plus BcfA (aPV/BcfA) generated IFNγ+ and IL-17+ CD4+ lung resident memory T cells (TRM), and CD4+IL-17+ TRM in the nose. In contrast, aPV alone delivered by the same route generated IL-5+ CD4+ resident memory T cells in the lungs and nose. Importantly, nasal colonization was only reduced in mice immunized with aPV/BcfA by the prime-pull regimen.

Conclusions

These results suggest that TH17 polarized TRM generated by aPV/BcfA may reduce nasal colonization thereby preventing pertussis transmission and subsequent resurgence.

Multiple rib and vertebral fractures associated with Bordetella pertussis infection: a case report

BACKGROUND

Pertussis is a highly contagious respiratory disease caused by the bacterium Bordetella pertussis, characterized by paroxysms of severe coughing, and predominantly affects children. We report the first case of multiple fractures in the ribs, lumbar spine, and sacrum associated with severe coughing caused by Bordetella pertussis infection in an adult.

CASE PRESENTATION

A 49-year-old female presented with acute-onset chest wall pain for 3 weeks. Imaging results revealed multiple fractures in the ribs and vertebrae, as well as bilateral pleural effusion, pericardial effusion, right pneumothorax, and enlargement of the left parapharyngeal and subclavian lymph nodes. The patient's bone density scan, autoimmune antibodies, bone marrow biopsy, and sacral bone biopsy all came back normal. Imaging test results found no evidence of solid tumors or active TB infection. The patient later recalled having violent coughing prior to the onset of chest pain and several family members having similar symptoms. Her blood sample was sent to the CDC, revealing Bordetella pertussis toxin (PT) IgG titer of 110.68 IU/mL. The patient was diagnosed with pertussis and multiple stress fractures from violent coughing. Symptomatic treatments were administered, and the patient's symptoms improved. The patient was followed up 8 weeks later, she reported no more coughing or chest pain.

CONCLUSIONS

Pertussis is not just a pediatric disease, but diagnosis in adults is challenging as patients may present with a myriad of confusing symptoms, such as multiple stress fractures due to violent coughing. Medical and epidemiological histories are key to reaching the correct diagnosis, which is essential for appropriate treatments to avoid further complications. Adult immunization should be suggested both for the protection of the adult population and to prevent transmission to children.

Architecture and matrix assembly determinants of Bordetella pertussis biofilms on primary human airway epithelium

Traditionally, whooping cough or pertussis caused by the obligate human pathogen Bordetella pertussis (Bp) is described as an acute disease with severe symptoms. However, many individuals who contract pertussis are either asymptomatic or show very mild symptoms and yet can serve as carriers and sources of bacterial transmission. Biofilms are an important survival mechanism for bacteria in human infections and disease. However, bacterial determinants that drive biofilm formation in humans are ill-defined. In the current study, we show that Bp infection of well-differentiated primary human bronchial epithelial cells leads to formation of bacterial aggregates, clusters, and highly structured biofilms which are colocalized with cilia. These findings mimic observations from pathological analyses of tissues from pertussis patients. Distinct arrangements (mono-, bi-, and tri-partite) of the polysaccharide Bps, extracellular DNA, and bacterial cells were visualized, suggesting complex heterogeneity in bacteria-matrix interactions. Analyses of mutant biofilms revealed positive roles in matrix production, cell cluster formation, and biofilm maturity for three critical Bp virulence factors: Bps, filamentous hemagglutinin, and adenylate cyclase toxin. Adherence assays identified Bps as a new Bp adhesin for primary human airway cells. Taken together, our results demonstrate the multi-factorial nature of the biofilm extracellular matrix and biofilm development process under conditions mimicking the human respiratory tract and highlight the importance of model systems resembling the natural host environment to investigate pathogenesis and potential therapeutic strategies.

A putative link between pertussis and new onset of gastroesophageal reflux. An observational study

Background

Pertussis is an infectious disease of the respiratory tract with a changing epidemiology. An increasing incidence has been found in the adult population with recurrent infections possibly related to changes in the current vaccine. Is there an association between pertussis infection, refractory cough and atypical gastro-oesophageal reflux (GORD)? Does this magnify and compound respiratory complications?

Methods

Observational study which compares post-pertussis (n=103) with non-pertussis patients (n=105) with established GORD. Patients were assessed for laryngopharyngeal reflux and aspiration of refluxate by a novel scintigraphic study.

Results

Both groups showed severe GORD in association with high rates of laryngopharyngeal reflux (LPR) and pulmonary aspiration and lung disease. High rates of hiatus hernia and clinical diagnosis of “atypical” asthma showed correlations with pulmonary aspiration.

Conclusions

A high level of new onset LPR and lung aspiration has been shown in patients with chronic cough after recent pertussis infection by a novel scintigraphic technique with fused hybrid x-ray computed tomography (SPECT/CT).

Pertussis vaccines

PURPOSE OF REVIEW

Pertussis is a vaccine preventable cough illness. It can be controlled by universal pertussis vaccination.

RECENT FINDINGS

Pertussis cases and deaths in children are at a record low number. More complete use of adolescent/adult vaccine can further reduce morbidity and mortality.

SUMMARY

Considerable progress in the control of pertussis has occurred over the last 75 years. The universal use of Tdap vaccines in all pregnant women will prevent virtually all pertussis deaths.

Epidemiology of pertussis in Costa Rica and the impact of vaccination: A 58-year experience (1961-2018)

Costa Rica is an upper middle-income country in Central America with a vigorous public health system. We have studied the number of cases, hospitalizations, and deaths due to pertussis from 1961 to 2018, in relation to vaccine coverage. Following the introduction of the fourth and fifth doses of DTP (booster doses) in 1973 there was a marked reduction of reported pertussis. In 2002 pertussis surveillance and laboratory diagnosis were improved. In 2007, Tdap post-partum immunization was introduced and then switched to intrapartum Tdap immunization in 2011. Of these two strategies post-partum vaccination seemed to have a greater effect in decreasing hospitalizations and deaths, nevertheless, since 2011 there has been only 4 infant deaths due to pertussis.

The need for pertussis vaccination among older adults and high-risk groups: a perspective from advanced economies of the Asia Pacific region

INTRODUCTION

Influenza and pneumococcal vaccines are the most regularly prescribed vaccines amongst adults <65 years of age. Pertussis booster vaccines (available as combined diphtheria-tetanus-acellular pertussis, Tdap) uptake is relatively low in many countries in the Asia-Pacific region. Increasing Tdap vaccination is a strategy that may aid healthy aging.Areas Covered: Epidemiology data, including notification reports from 6 advanced economies in Asia (Australia, Hong Kong, New Zealand, Singapore, South Korea, and Taiwan) were reviewed to assess the pertussis disease burden and identify high-risk groups. Existing Tdap vaccination recommendations were reviewed. Current vaccination practices were discussed to benchmark and identify barriers and success factors for Tdap booster vaccination in older adults.Expert Opinion: The available evidence supports Tdap vaccination at an individual level for the prevention of pertussis, along with tetanus and diphtheria in those aged 65+ years, together with influenza and pneumococcal vaccination. Data gaps need to be filled to support the development of national/supranational recommendations for pertussis booster vaccination. Groups at higher risk of pertussis infection and its complications, including those with chronic obstructive pulmonary disease and asthma, could be considered as priority groups. Increasing disease awareness and establishing adult vaccination registries could improve vaccine coverage and promote healthy aging.

Pertussis seroprevalence among adults of reproductive age (20-39 years) in fourteen European countries

The reported incidence of pertussis in European countries varies considerably. We aimed to study specific Bordetella pertussis seroprevalence in Europe by measuring serum IgG antibody levels to pertussis toxin (anti-PT IgG). Fourteen national laboratories participated in this study including Belgium, Denmark, Finland, Greece, Hungary, Italy, Lithuania, Malta, Norway, Poland, Portugal, Romania, Spain, and Sweden. Each country collected approximately 250 samples (N = 7903) from the age groups 20-29 years (N = 3976) and 30-39 years (N = 3927) during 2010-2013. Samples were anonymous residual sera from diagnostic laboratories and were analyzed at the national laboratories by a Swedish reference method, a commercial ELISA kit, or were sent to Sweden for analysis. The median anti-PT IgG concentrations ranged from 4 to 13.6 IU/mL. The proportion of samples with anti-PT IgG ≥100 IU/mL, indicating a recent infection ranged from 0.2% (Hungary) to 5.7% (Portugal). The highest proportion of sera with anti-PT IgG levels between 50 and <100 IU/mL, indicating an infection within the last few years, was found in Portugal (12.3%) and Italy (13.9%). This study shows that the circulation of B. pertussis is quite extensive in adults, aged 20-39 years, despite well-established vaccination programs in Europe.

Decline of serologic immunity to diphtheria, tetanus and pertussis with age suggested a full life vaccination in mainland China

Background: Diphtheria-tetanus-pertussis (DTP) vaccine has already been involved in national vaccination program for several decades in China. The immunity against these diseases in the people of all ages is not well investigated.Materials and methods: Serum samples were tested for IgG antibodies to diphtheria toxoid (DT), tetanus toxoid (TT) and pertussis toxin (PT) by using commercial ELISA kits.Results: A total of 666 sera of patients from 1 day to 89 years of age was collected from 2018 to 2019. The protective rates of diphtheria, tetanus and pertussis were 45.5%, 54.4% and 4.7%, respectively. Only 4.7% of the study population had seropositivity against three of the diseases. Young infant (<3 m) and adult (>18y) were generally lack of protective antibody against diphtheria (81.7% and 58.3%) and tetanus (91.5% and 86.2%). An obvious increase in immunity level of diphtheria and tetanus was observed at 3 m-3y, but there was no significant increase of immunity to pertussis at any age group. All age groups showed low immunity to pertussis.Conclusions: The present results revealed the susceptibility to diphtheria and tetanus in young infants and adults, and the susceptibility to pertussis over the ages, which highlight the need to improve the current vaccination program.

Circulation of pertussis and poor protection against diphtheria among middle-aged adults in 18 European countries

Reported incidence of pertussis in the European Union (EU) and the European Economic Area (EEA) varies and may not reflect the real situation, while vaccine-induced protection against diphtheria and tetanus seems sufficient. We aimed to determine the seroprevalence of DTP antibodies in EU/EEA countries within the age groups of 40-49 and 50-59 years. Eighteen countries collected around 500 samples between 2015 and 2018 (N = 10,302) which were analysed for IgG-DTP specific antibodies. The proportion of sera with pertussis toxin antibody levels ≥100 IU/mL, indicative of recent exposure to pertussis was comparable for 13/18 countries, ranging between 2.7-5.8%. For diphtheria the proportion of sera lacking the protective level (<0.1 IU/mL) varied between 22.8-82.0%. For tetanus the protection was sufficient. Here, we report that the seroprevalence of pertussis in these age groups indicates circulation of B. pertussis across EU/EEA while the lack of vaccine-induced seroprotection against diphtheria is of concern and deserves further attention.

Seroprevalence of Bordetella pertussis among a nationally representative sample of Iranian pediatric population: The childhood and adolescence surveillance and prevention of adult noncommunicable disease-V study

Background:

Pertussis is a vaccine-preventable respiratory infection and seroepidemiology of the infection could be a marker of the pertussis immunity in a population. In many countries, despite vaccination coverage, high prevalence of pertussis has been observed. The present study aimed to evaluate the immunoglobulin G (IgG) antibody against pertussis and the role of demographic and anthropometric variables on the immunity rate in the Iranian pediatric population to evaluate the impact of existing immunization program in order to envisage future vaccination strategies to prevent infection.

Methods:

In a cross-sectional multi-centric study, 1593 samples of the students aged 7–18 years, who had been enrolled in a national survey (Childhood and Adolescence Surveillance and Prevention of Adult Noncommunicable disease-V), were randomly selected and tested for IgG antibody against Bordetella pertussis (BP) by enzyme-linked immunosorbent assay. The age, gender, education, residency, geographical region, and body mass index (BMI) were extracted from the questionnaires of the COSPIAN-Survey. Multiple logistic regression models were used to assess the associations between the variables with the IgG antibody against BP. Data were presented by odds ratio (OR), 95% confidence interval (95% CI) and P values (P): (OR [95% CI]; P).

Results:

Subjects were consisted of 774 boys and 750 girls, with a mean (standard deviation) age of 12.39 (3.03) years. Overall, BP seroprevalence was 59.8%. There were higher BMI values in seronegative ones versus seropositive (18.62 ± 4.07 vs. 18.15 ± 3.94, P = 0.041, 95% CI = 0.23 [0.02–0.92]). However, the categorized BMI for age was not significantly associated with IgG levels (0.27 [0.25–0.29]; 0.27). BP seroprevalence was not significantly different between geographical regions (0.06 [0.05–0.07]; 0.06), genders (1.17 [0.93–1.47]; 0.18), area of residence (1.07 [0.82–1.4]; 0.61), and educational levels (0.94 [0.75–1.19]; 0.62).

Conclusion:

IgG antibody against pertussis was not detected in nearly 40% of the subjects who had history of vaccination against pertussis. It is recommended to monitor the incidence of pertussis in high-risk populations closely and administer a booster dose of acellular pertussis vaccine in adolescents.

A profile of the Simplexa™ Bordetella Direct assay for the detection and differentiation of Bordetella pertussis and Bordetella parapertussis in nasopharyngeal swabs

INTRODUCTION

Pertussis is a highly contagious respiratory infection caused by Bordetella pertussis and to minor extent B. parapertussis. Despite high vaccination coverage, epidemics persist worldwide. Laboratory testing with the capacity to support increasing demand and generate fast and accurate results is needed to promptly provide treatment to mitigate symptoms, prevent transmission, and thus impact infection control and disease surveillance.

AREAS COVERED

This review will describe the features of the Simplexa™ Bordetella Direct Assay and compare this technology with other existing assays. Unmet needs and future directions will be discussed.

EXPERT COMMENTARY

Resurgence of pertussis highlights the importance of reliable and accurate diagnosis. The Simplexa™ Bordetella Direct Assay provides an easy workflow, reduced hand-on time, less risk of contamination, and rapid turnaround time. The use of efficient molecular assays in routine clinical laboratory is valuable for increasing demand, improvement of infection control, and surveillance.

Cost-effectiveness analysis of universal adult immunization with tetanus-diphtheria-acellular pertussis vaccine (Tdap) versus current practice in Brazil

BACKGROUND

A pertussis outbreak occurred in Brazil from 2011 to 2014, despite high coverage of whole-cell pertussis containing vaccines in early childhood. Infants were the most affected. This study aimed to evaluate the cost-effectiveness of introducing universal adult vaccination with Tdap into the National Immunization Program in Brazil.

METHODS

Economic evaluation using a dynamic model to compare two strategies: (1) universal vaccination with single dose of Tdap at 20 years of age and (2) current practice (only pregnant women pertussis vaccination). The health system perspective was adopted. Temporal horizon was 10 years. Discount rate of 5% was applied to costs and benefits. Vaccine effectiveness (VE) was obtained from a population-based observational study. Epidemiological, resource utilization and cost estimates were obtained from the Brazilian Health Information Systems. The primary outcome was cost per life year saved (LYS), based on life expectancy at birth in Brazil in 2015. Univariate and multivariate sensitivity analysis were performed.

RESULTS

Adult vaccination with VE of 82.6% and coverage of 40%, at price of US$7.01 per dose, and assuming herd protection would avoid 167 infant deaths by pertussis, saving 12,325 years of life and costing a total of US$105495891.61, from the health system perspective. The universal immunization would result in ICER of US$8459.13. The results were highly sensitive to disease incidence.

CONCLUSIONS

The results suggest that universal adult vaccination with Tdap would not be a cost-effective intervention for preventing pertussis cases and deaths in infants in Brazil.

The 112-Year Odyssey of Pertussis and Pertussis Vaccines-Mistakes Made and Implications for the Future

Effective diphtheria, tetanus toxoids, whole-cell pertussis (DTwP) vaccines became available in the 1930s, and they were put into routine use in the United States in the 1940s. Their use reduced the average rate of reported pertussis cases from 157 in 100 000 in the prevaccine era to <1 in 100 000 in the 1970s. Because of alleged reactions (encephalopathy and death), several countries discontinued (Sweden) or markedly decreased (United Kingdom, Germany, Japan) use of the vaccine. During the 20th century, Bordetella pertussis was studied extensively in animal model systems, and many "toxins" and protective antigens were described. A leader in B pertussis research was Margaret Pittman of the National Institutes of Health/US Food and Drug Administration. She published 2 articles suggesting that pertussis was a pertussis toxin (PT)-mediated disease. Dr Pittman's views led to the idea that less-reactogenic acellular vaccines could be produced. The first diphtheria, tetanus, pertussis (DTaP) vaccines were developed in Japan and put into routine use there. Afterward, DTaP vaccines were developed in the Western world, and definitive efficacy trials were carried out in the 1990s. These vaccines were all less reactogenic than DTwP vaccines, and despite the fact that their efficacy was less than that of DTwP vaccines, they were approved in the United States and many other countries. DTaP vaccines replaced DTwP vaccines in the United States in 1997. In the last 13 years, major pertussis epidemics have occurred in the United States, and numerous studies have shown the deficiencies of DTaP vaccines, including the small number of antigens that the vaccines contain and the type of cellular immune response that they elicit. The type of cellular response a predominantly, T2 response results in less efficacy and shorter duration of protection. Because of the small number of antigens (3-5 in DTaP vaccines vs >3000 in DTwP vaccines), linked-epitope suppression occurs. Because of linked-epitope suppression, all children who were primed by DTaP vaccines will be more susceptible to pertussis throughout their lifetimes, and there is no easy way to decrease this increased lifetime susceptibility.

The burden of pertussis in older adults: what is the role of vaccination? A systematic literature review

INTRODUCTION

Pertussis (whooping cough) is a vaccine-preventable disease; however, neither natural- nor vaccine-induced protection is life-long. Although generally not severe in adults, pertussis can be associated with complications in patients with chronic conditions such as asthma or chronic obstructive pulmonary disease, and can be readily transmitted to more vulnerable populations, including neonates before they complete their primary vaccination. Furthermore, as the global population ages, the health and economic burden of the disease is expected to rise. Areas covered: A systematic literature review was conducted to ascertain the current epidemiological and financial burden of pertussis in older adults and to discuss the potential value of a booster vaccination in this population. Expert commentary: Our review indicates a considerable underestimation of the pertussis burden amongst older adults. Seroprevalence studies consistently demonstrate that the reported incidence may be much lower than the actual incidence. Tetanus toxoid-reduced diphtheria toxoid and acellular pertussis vaccines are immunogenic in older adults, induce high booster responses and are well-tolerated. There is therefore a good rationale for the advocacy of booster pertussis vaccination throughout life to prevent pertussis infection and its transmission, especially in adults aged ≥50 years.

Reprogramming the adjuvant properties of aluminum oxyhydroxide with nanoparticle technology

Aluminum salts, developed almost a century ago, remain the most commonly used adjuvant for licensed human vaccines. Compared to more recently developed vaccine adjuvants, aluminum adjuvants such as Alhydrogel are heterogeneous in nature, consisting of 1–10 micrometer-sized aggregates of nanoparticle aluminum oxyhydroxide fibers. To determine whether the particle size and aggregated state of aluminum oxyhydroxide affects its adjuvant activity, we developed a scalable, top-down process to produce stable nanoparticles (nanoalum) from the clinical adjuvant Alhydrogel by including poly(acrylic acid) (PAA) polymer as a stabilizing agent. Surprisingly, the PAA:nanoalum adjuvant elicited a robust TH1 immune response characterized by antigen-specific CD4⁺ T cells expressing IFN-γ and TNF, as well as high IgG2 titers, whereas the parent Alhydrogel and PAA elicited modest TH2 immunity characterized by IgG1 antibodies. ASC, NLRP3 and the IL-18R were all essential for TH1 induction, indicating an essential role of the inflammasome in this adjuvant’s activity. Compared to microparticle Alhydrogel this nanoalum adjuvant provided superior immunogenicity and increased protective efficacy against lethal influenza challenge. Therefore PAA:nanoalum represents a new class of alum adjuvant that preferentially enhances TH1 immunity to vaccine antigens. This adjuvant may be widely beneficial to vaccines for which TH1 immunity is important, including tuberculosis, pertussis, and malaria.

Aluminum salt-based adjuvants such as alhydrogel have been a mainstay of vaccines for decades. Christopher B. Fox and colleagues at the Infectious Disease Research Institute in Seattle, USA, investigate the effect adjuvant particle size has on experimental vaccine responses. Shearing conventional micrometer-scale alhyrodogel into nanoparticles is followed by rapid reaggregation; however, the authors show that addition of anionic polymer (PAA) prevents this and results in stable nanoparticles (PAA:nanoalum). Used as an adjuvant with either influenza or TB antigens triggers robust TH1 and IgG2a responses that are superior to alhydrogel even when the latter includes a Toll-like receptor 4 (TLR4) agonist. Interestingly, addition of TLR4 agonist to PAA:nanoalum actually impairs its adjuvanticity. PAA:nanoalum efficacy is nevertheless dependent on the NLRP3 inflammasome suggesting that this novel adjuvant somehow triggers this pathway through some as yet undefined route.

Humoral immunity 10 years after booster immunization with an adolescent and adult formulation combined tetanus, diphtheria, and 5-component acellular pertussis vaccine in the USA

BACKGROUND

In a prospective, randomized pivotal phase III clinical trial, the immunogenicity and reactogenicity of a tetanus-diphtheria-acellular pertussis vaccine (Tdap) and a tetanus-diphtheria vaccine (Td) vaccine were studied in participants aged 11-64 years. Here we report antibody persistence through 10 years after vaccination.

METHODS

Participants who received Tdap or Td in the original phase III trial and provided pre- and post-vaccination serum samples were recruited to donate sera at 1, 3, 5 and 10 years post-vaccination. Antibody concentrations were measured using standard assay techniques.

RESULTS

Initially, 1457 Tdap and 1152 Td recipients were included; of these, 175 persons from Tdap group were available at the final study bleed point. Nearly all adolescents in both groups had diphtheria antibody levels ≥0.1 IU/mL 1 month after vaccination, which were maintained in ≥95% of vaccinees at 5 and 10 years. Among adults, ≥94% had diphtheria antibody levels ≥0.1 IU/mL 1 month after vaccination, which were maintained in ≥80% at 5 and 10 years. Nearly all participants had tetanus antibodies ≥0.1 IU/mL throughout the study. PT antibodies declined to pre-vaccination levels approximately 5 years post-vaccination; FHA, PRN and FIM antibodies waned at 5 and 10 years but remained several-fold higher than pre-vaccination levels.

CONCLUSIONS

Tdap and Td provide long-lasting protective immune responses against diphtheria and tetanus. Pertussis antibodies following Tdap generally exceeded pre-vaccination levels throughout the study, but showed substantial waning. These data may inform discussion of the need for repeat Tdap booster vaccinations among adults.

TRIAL REGISTRATION

The original phase III clinical trial, as well as the 1-, 3-, and 5-year serology follow-up studies were conducted prior to mandatory registration. The 10-year serology follow-up data collection was performed as part of a repeat Tdap administration clinical trial that was registered under clinicaltrials.gov number NCT01439165.

Evidence of cryptic incidence in childhood diseases

Persistence and extinction are key processes in infectious disease dynamics that, owing to incomplete reporting, are seldom directly observable. For fully immunizing diseases, reporting probabilities can be readily estimated from demographic records and case reports. Yet reporting probabilities are not sufficient to unambiguously reconstruct disease incidence from case reports. Here, we focus on disease presence (i.e. marginal probability of non-zero incidence), which provides an upper bound on the marginal probability of disease extinction. We examine measles and pertussis in pre-vaccine era United States (US) cities, and describe a conserved scaling relationship between population size, reporting probability and observed presence (i.e. non-zero case reports). We use this relationship to estimate disease presence given perfect reporting, and define cryptic presence as the difference between estimated and observed presence. We estimate that, in early twentieth century US cities, pertussis presence was higher than measles presence across a range of population sizes, and that cryptic presence was common in small cities with imperfect reporting. While the methods employed here are specific to fully immunizing diseases, our results suggest that cryptic incidence deserves careful attention, particularly in diseases with low case counts, poor reporting and longer infectious periods.

Systematic review found that there was moderate evidence that vaccinating healthcare workers prevented pertussis in infants

This systematic review investigated the effectiveness of vaccinating healthcare workers against pertussis on the occurrence of nosocomial pertussis outbreaks or infections among unprotected infants. We focused on eight studies, with five different study designs, that involved 39,129 healthy adolescents and adults, 115 healthcare workers, 2000 simulated healthcare workers and a simulated population of 200,000 people.

CONCLUSION

There was moderate evidence that tetanus-diphtheria acellular pertussis vaccinations for healthcare workers were effective in preventing pertussis in all age groups and specifically in infants. The results must be interpreted with caution due to the low quality and heterogeneity of the studies.

Pertussis in Young Infants Throughout the World

In typical pertussis in young infants, the child will appear deceptively well; he or she will have coryza, sneezing, and a mild cough. There is no fever. This progresses to gagging, gasping, eye bulging, bradycardia, cyanosis, and vomiting. There is leukocytosis with lymphocytosis and apneic episodes. Deaths relate to leukocytosis, pulmonary hypertension, and pneumonia. The source of pertussis in young infants is most often a family member with cough illness that is not recognized as pertussis. Diagnosis is based on culture/polymerase chain reaction and leukocytosis with lymphocytosis. Treatment depends on macrolide antibiotic therapy and intubation, with assisted ventilation and oxygen. Prevention is based on prophylactic macrolide treatment, immunization starting at 6 weeks of age, and immunization of all pregnant women in the second or third trimester.

What Is Wrong with Pertussis Vaccine Immunity? The Problem of Waning Effectiveness of Pertussis Vaccines

Pertussis is resurgent in some countries, particularly those in which children receive acellular pertussis (aP) vaccines in early infancy and boosters later in life. Immunologic studies show that, whereas whole-cell pertussis (wP) vaccines orient the immune system toward Th1/Th17 responses, acellular pertussis vaccines orient toward Th1/Th2 responses. Although aP vaccines do provide protection during the first years of life, the change in T-cell priming results in waning effectiveness of aP as early as 2-3 years post-boosters. Although other factors, such as increased virulence of pertussis strains, better diagnosis, and better surveillance may play a role, the increase in pertussis appears to be the result of waning immunity. In addition, studies in baboon models, requiring confirmation in humans, show that aP is less able to prevent nasopharyngeal colonization of Bordetella pertussis than wP or natural infection.

Pertussis: Microbiology, Disease, Treatment, and Prevention

Pertussis is a severe respiratory infection caused by Bordetella pertussis, and in 2008, pertussis was associated with an estimated 16 million cases and 195,000 deaths globally. Sizeable outbreaks of pertussis have been reported over the past 5 years, and disease reemergence has been the focus of international attention to develop a deeper understanding of pathogen virulence and genetic evolution of B. pertussis strains. During the past 20 years, the scientific community has recognized pertussis among adults as well as infants and children. Increased recognition that older children and adolescents are at risk for disease and may transmit B. pertussis to younger siblings has underscored the need to better understand the role of innate, humoral, and cell-mediated immunity, including the role of waning immunity. Although recognition of adult pertussis has increased in tandem with a better understanding of B. pertussis pathogenesis, pertussis in neonates and adults can manifest with atypical clinical presentations. Such disease patterns make pertussis recognition difficult and lead to delays in treatment. Ongoing research using newer tools for molecular analysis holds promise for improved understanding of pertussis epidemiology, bacterial pathogenesis, bioinformatics, and immunology. Together, these advances provide a foundation for the development of new-generation diagnostics, therapeutics, and vaccines.

Pertussis Vaccine Effectiveness in the Setting of Pertactin-Deficient Pertussis

BACKGROUND

In the United States, the proportion of Bordetella pertussis isolates lacking pertactin, a component of acellular pertussis vaccines, increased from 14% in 2010 to 85% in 2012. The impact on vaccine effectiveness (VE) is unknown.

METHODS

We conducted 2 matched case-control evaluations in Vermont to assess VE of the 5-dose diphtheria, tetanus, and acellular pertussis vaccine (DTaP) series among 4- to 10-year-olds, and tetanus, diphtheria, and acellular pertussis vaccine (Tdap) among 11- to 19-year-olds. Cases reported during 2011 to 2013 were included. Three controls were matched to each case by medical home, and additionally by birth year for the Tdap evaluation. Vaccination history was obtained from medical records and parent interviews. Odds ratios (OR) were calculated by using conditional logistic regression; VE was estimated as (1-OR) × 100%. Pertactin status was determined for cases with available isolates.

RESULTS

Overall DTaP VE was 84% (95% confidence interval [CI] 58%-94%). VE within 12 months of dose 5 was 90% (95% CI 71%-97%), declining to 68% (95% CI 10%-88%) by 5-7 years post-vaccination. Overall Tdap VE was 70% (95% CI 54%-81%). Within 12 months of Tdap vaccination, VE was 76% (95% CI 60%-85%), declining to 56% (95% CI 16%-77%) by 2-4 years post-vaccination. Of cases with available isolates, >90% were pertactin-deficient.

CONCLUSIONS

Our DTaP and Tdap VE estimates remain similar to those found in other settings, despite high prevalence of pertactin deficiency in Vermont, suggesting these vaccines continue to be protective against reported pertussis disease.

Whooping cough in a renal transplant recipient

Whooping cough is a respiratory infection with a severity that varies with age, immune status, and probably with other factors such as the degree of exposure and the virulence of the organism. The most frequent microorganism responsible for whooping cough is Bordetella pertussis. We present the case of a 62-year-old renal transplant recipient presenting with typical and severe manifestations of whooping cough caused by B. pertussis.

Bordetella pertussis epidemiology and evolution in the light of pertussis resurgence

Whooping cough, or pertussis, is resurgent in many countries world-wide. This is linked to switching from the use of whole cell vaccines to acellular vaccines in developed countries. Current evidence suggests that this has resulted in the earlier waning of vaccine-induced immunity, an increase in asymptomatic infection with concomitant increases in transmission and increased selection pressure for Bordetellapertussis variants that are better able to evade vaccine-mediated immunity than older isolates. This review discusses recent findings in B. pertussis epidemiology and evolution in the light of pertussis resurgence, and highlights the important role for genomics-based studies in monitoring B. pertussis adaptation.

Protecting Newborns Against Pertussis: Treatment and Prevention Strategies

Pertussis is a potentially severe respiratory disease, which affects all age groups from young infants to older adults and is responsible for an estimated 195,000 deaths occurred globally in 2008. Active research is ongoing to better understand the pathogenesis, immunology, and diagnosis of pertussis. For diagnosis, molecular assays (e.g., polymerase chain reaction) for detection of Bordetella pertussis have become more widely available and support improved outbreak detection. In children, pertussis vaccines have been incorporated into routine immunization schedules and deployed for pertussis outbreak control. Lower levels of vaccine coverage are now being observed in communities where vaccine hesitancy is rising. Additionally, recognition that newborn babies are at risk of pertussis in the USA and UK has led to recommendations to immunize pregnant women. Among adolescents and older adults in the USA, Tetanus Toxoid, Reduced Diphtheria Toxoid and Acellular pertussis (Tdap) Vaccines are recommended, but substantial individual- and system-level barriers exist that will make achieving national Healthy People 2020 targets for immunization challenging. Current antimicrobial regimens for pertussis are focused on reducing the severity of disease, reducing rates of sequelae, and minimizing transmission of infection to susceptible individuals. Continued surveillance for pertussis will be important to identify opportunities for reducing young infants' exposure and reducing the impact of outbreaks among school-aged children. Laboratory-based surveillance for newly emerging strains of B. pertussis will be important to identify strains that may evade protection elicited by currently available vaccines. Efforts to develop new-generation pertussis vaccines should be considered now in anticipation of vaccine development programs, which may require ten or more years to deliver a licensed vaccine.

Bordetella biofilms: a lifestyle leading to persistent infections

Bordetella bronchiseptica and B. pertussis are Gram-negative bacteria that cause respiratory diseases in animals and humans. The current incidence of whooping cough or pertussis caused by B. pertussis has reached levels not observed since the 1950s. Although pertussis is traditionally known as an acute childhood disease, it has recently resurged in vaccinated adolescents and adults. These individuals often become silent carriers, facilitating bacterial circulation and transmission. Similarly, vaccinated and non-vaccinated animals continue to be carriers of B. bronchiseptica and shed bacteria resulting in disease outbreaks. The persistence mechanisms of these bacteria remain poorly characterized. It has been proposed that adoption of a biofilm lifestyle allows persistent colonization of the mammalian respiratory tract. The history of Bordetella biofilm research is only a decade long and there is no single review article that has exclusively focused on this area. We systematically discuss the role of Bordetella factors in biofilm development in vitro and in the mouse respiratory tract. We further outline the implications of biofilms to bacterial persistence and transmission in humans and for the design of new acellular pertussis vaccines.

Predicting future trends in the burden of pertussis in the 21st century: implications for infant pertussis and the success of maternal immunization

Support is growing for maternal immunization using acellular pertussis (aP) vaccines to prevent severe pertussis disease and deaths among very young, unvaccinated infants. Vaccine effectiveness of maternal immunization is 91% in preventing laboratory-confirmed pertussis in infants aged <3 months. To date, most mothers were primed in childhood with whole-cell pertussis vaccines. Soon, the generation of aP-primed individuals will become the new mothers-to-be. The shorter duration of protection afforded by aP vaccines, which is more pronounced with repeated aP boosters, may lead to increased pertussis circulation among aP-primed parents. Maternal Tdap immunization in aP-primed mothers-to-be may become less effective. Additional measures to protect young infants may eventually be needed, along with new vaccines that induce higher quality and more durable responses.

Respiratory infection with a bacterial pathogen attenuates CNS autoimmunity through IL-10 induction

Infection with viral or bacterial pathogens has been linked with the development of multiple sclerosis (MS), while infection with helminth parasites has been associated protection against MS and other autoimmune diseases. Here we have used a murine model of MS, experimental autoimmune encephalomyelitis (EAE), to examine the effect of infection with the respiratory pathogen Bordetella pertussis infection on development of CNS inflammation. The data demonstrate that infection of mice with B. pertussis significantly attenuates the clinical course of EAE induced by active immunization or cell transfer. This was reflected in a significant reduction in VLA-4 and LFA-1 expression on T cells and infiltration of IL-17(+), IFN-γ(+) and IFN-γ(+)IL-17(+) CD4 T cells into the CNS. Infection with B. pertussis induced IL-10 production from dendritic cells in vitro and enhanced the frequency of IL-10-producing CD25(-)Foxp3(+/-) CD4(+) T cells in vivo. Furthermore, the suppressive effects of B. pertussis infection on EAE were lost in IL-10(-/-) mice. Our findings demonstrate that a bacterial infection of the respiratory tract can attenuate EAE by promoting production of the anti-inflammatory cytokine IL-10 that may suppress licensing of autoaggressive T cells in the lungs, thereby preventing their migration into the CNS.

Highly differentiated human airway epithelial cells: a model to study host cell-parasite interactions in pertussis

BACKGROUND

Bordetella pertussis colonizes the human respiratory mucosa. Most studies on B. pertussis adherence have relied on cultured mammalian cells that lack key features present in differentiated human airway cells or on animal models that are not natural hosts of B. pertussis. The objectives of this work were to evaluate B. pertussis infection in highly differentiated human airway cells in vitro and to show the role of B. pertussis fimbriae in cell adherence.

METHODS

Primary human airway epithelial (PHAE) cells from human bronchi and a human bronchial epithelial (HBE) cell line were grown in vitro under air-liquid interface conditions.

RESULTS

PHAE and HBE cells infected with B. pertussis wild-type strain revealed bacterial adherence to the apical surface of cells, bacteria-induced cytoskeleton changes, and cell detachment. Mutations in the major fimbrial subunits Fim2/3 or in the minor fimbrial adhesin subunit FimD affected B. pertussis adherence to predominantly HBE cells. This cell model recapitulates the morphologic features of the human airway infected by B. pertussis and confirms the role of fimbriae in B. pertussis adherence. Furthermore, HBE cells show that fimbrial subunits, and specifically FimD adhesin, are critical in B. pertussis adherence to airway cells.

CONCLUSIONS

The relevance of this model to study host-parasite interaction in pertussis lies in the striking physiologic and morphologic similarity between the PHAE and HBE cells and the human airway ciliated and goblet cells in vivo. These cells can proliferate in vitro, differentiate, and express the same genetic profile as human respiratory cells in vivo.

Laboratory Diagnosis of Pertussis

The introduction of vaccination in the 1950s significantly reduced the morbidity and mortality of pertussis. However, since the 1990s, a resurgence of pertussis has been observed in vaccinated populations, and a number of causes have been proposed for this phenomenon, including improved diagnostics, increased awareness, waning immunity, and pathogen adaptation. The resurgence of pertussis highlights the importance of standardized, sensitive, and specific laboratory diagnoses, the lack of which is responsible for the large differences in pertussis notifications between countries. Accurate laboratory diagnosis is also important for distinguishing between the several etiologic agents of pertussis-like diseases, which involve both viruses and bacteria. If pertussis is diagnosed in a timely manner, antibiotic treatment of the patient can mitigate the symptoms and prevent transmission. During an outbreak, timely diagnosis of pertussis allows prophylactic treatment of infants too young to be (fully) vaccinated, for whom pertussis is a severe, sometimes fatal disease. Finally, reliable diagnosis of pertussis is required to reveal trends in the (age-specific) disease incidence, which may point to changes in vaccine efficacy, waning immunity, and the emergence of vaccine-adapted strains. Here we review current approaches to the diagnosis of pertussis and discuss their limitations and strengths. In particular, we emphasize that the optimal diagnostic procedure depends on the stage of the disease, the age of the patient, and the vaccination status of the patient.