Pertussis infection among adults during the 1993 outbreak in Chicago

Immunological and Clinical Benefits of Maternal Immunization Against Pertussis: A Systematic Review

Infants are vulnerable to pertussis infection particularly before initiation of pertussis vaccination. Maternal pertussis vaccination during pregnancy has been introduced in a number of countries in order to confer on young infants indirect protection from the disease through transplacental transfer of maternal antibodies. We reviewed the evidence on the immunogenicity and efficacy of maternal pertussis vaccination during pregnancy. A systematic search of PubMed/MEDLINE, EMBASE, Scopus, Cochrane Database of Systematic Reviews, ProQuest, and Science Direct was undertaken to identify studies published between January 1995 and December 2018. This review was not specific to any particular pertussis vaccine but included applicable data on available pertussis vaccines administered to pregnant women. The search identified 40 publications for inclusion in this review. Vaccination during pregnancy elicited robust maternal immune responses against all vaccine antigens and resulted in high placental transfer of pertussis antibodies to the infant that persisted well beyond delivery. Vaccination during the second or early third trimesters was considered ideal for antibody quantity and functionality. Although blunting of immune responses to some antigens in the primary immunization series was documented in neonates born to women vaccinated during pregnancy, there was no apparent adverse effect on vaccine efficacy. Multiple studies conducted in diverse settings have confirmed the effectiveness of maternal pertussis vaccination during pregnancy in preventing pertussis in infants prior to receipt of their first primary vaccine dose and beyond. These findings collectively underscore the value of maternal pertussis vaccination during pregnancy in protecting vulnerable infants too young to be vaccinated.Funding Sanofi Pasteur.Plain Language Summary Plain language summary available for this article.

Clinically Diagnosing Pertussis-associated Cough in Adults and Children: CHEST Guideline and Expert Panel Report

BACKGROUND

The decision to treat a suspected case of pertussis with antibiotics is usually based on a clinical diagnosis rather than waiting for laboratory confirmation. The current guideline focuses on making the clinical diagnosis of pertussis-associated cough in adults and children.

METHODS

The American College of Chest Physicians (CHEST) methodologic guidelines and the Grading of Recommendations, Assessment, Development, and Evaluation framework were used. The Expert Cough Panel based their recommendations on findings from a systematic review that was recently published on the topic; final grading was reached by consensus according to Delphi methodology. The systematic review was carried out to answer the Key Clinical Question: In patients presenting with cough, how can we most accurately diagnose from clinical features alone those who have pertussis-associated cough as opposed to other causes of cough?

RESULTS

In adults, after pre-specified meta-analysis exclusions, pooled estimates of sensitivity and specificity were generated for only 4 clinical features: paroxysmal cough, post-tussive vomiting, inspiratory whooping, and absence of fever. Both paroxysmal cough and absence of fever had high sensitivity (93.2% [95% CI, 83.2-97.4] and 81.8% [95% CI, 72.2-88.7], respectively) and low specificity (20.6% [95% CI, 14.7-28.1] and 18.8% [95% CI, 8.1-37.9]). Inspiratory whooping and posttussive vomiting had a low sensitivity (32.5% [95% CI, 24.5-41.6] and 29.8% [95% CI, 18.0-45.2]) but high specificity (77.7% [95% CI, 73.1-81.7] and 79.5% [95% CI, 69.4-86.9]). In children, after pre-specified meta-analysis exclusions, pooled estimates of sensitivity and specificity were generated for only 1 clinical feature in children (0-18 years): posttussive vomiting. Posttussive vomiting in children was only moderately sensitive (60.0% [95% CI, 40.3-77.0]) and specific (66.0% [95% CI, 52.5-77.3]).

CONCLUSIONS

In adults with acute (< 3 weeks) or subacute (3-8 weeks) cough, the presence of whooping or posttussive vomiting should rule in a possible diagnosis of pertussis, whereas the lack of a paroxysmal cough or the presence of fever should rule it out. In children with acute (< 4 weeks) cough, posttussive vomiting is suggestive of pertussis but is much less helpful as a clinical diagnostic test. Guideline suggestions are made based upon these findings and conclusions.

Clinical Characteristics of Pertussis-Associated Cough in Adults and Children: A Diagnostic Systematic Review and Meta-Analysis

BACKGROUND

Pertussis (whooping cough) is a highly infective cause of cough that causes significant morbidity and mortality. Existing case definitions include paroxysmal cough, whooping, and posttussive vomiting, but diagnosis can be difficult. We determined the diagnostic accuracy of clinical characteristics of pertussis-associated cough.

METHODS

We systematically searched CINAHL, Embase, Medline, and SCI-EXPANDED/CPCI-S up to June 2016. Eligible studies compared clinical characteristics in those positive and negative for Bordetella pertussis infection, confirmed by laboratory investigations. Two authors independently completed screening, data extraction, and quality and bias assessments. For each characteristic, RevMan was used to produce descriptive forest plots. The bivariate meta-analysis method was used to generate pooled estimates of sensitivity and specificity.

RESULTS

Of 1,969 identified papers, 53 were included. Forty-one clinical characteristics were assessed for diagnostic accuracy. In adult patients, paroxysmal cough and absence of fever have a high sensitivity (93.2% [CI, 83.2-97.4] and 81.8% [CI, 72.2-88.7], respectively) and low specificity (20.6% [CI, 14.7-28.1] and 18.8% [CI, 8.1-37.9]), whereas posttussive vomiting and whooping have low sensitivity (32.5% [CI, 24.5-41.6] and 29.8% [CI, 8.0-45.2]) and high specificity (77.7% [CI, 73.1-81.7] and 79.5% [CI, 69.4-86.9]). Posttussive vomiting in children is moderately sensitive (60.0% [CI, 40.3-77.0]) and specific (66.0% [CI, 52.5-77.3]).

CONCLUSIONS

In adult patients, the presence of whooping or posttussive vomiting should rule in a possible diagnosis of pertussis, whereas the lack of a paroxysmal cough or the presence of fever should rule it out. In children, posttussive vomiting is much less helpful as a clinical diagnostic test.

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.

Whooping cough in 2014 and beyond: an update and review

Pertussis, or whooping cough, has had a dramatic resurgence in the past several years and is the most common vaccine-preventable disease in the world. The year 2012 marked the most cases in the United States in &gt; 50 years. Large outbreaks have occurred in multiple states, and infant deaths have drawn the attention of not only health-care providers but also the media. Although the disease is theoretically preventable by vaccination, it remains a challenge to control. New vaccination strategies have been implemented across different age groups and populations of patients, but vaccine coverage remains dismally low. Acellular vaccines, although safe, do not afford the same long-lasting immunity as the previously used whole-cell vaccine. Ultimately, improvements in the development of vaccines and in vaccination coverage will be essential to decrease the burden of pertussis on society. This article provides a review of pertussis infection and discusses advances related to the epidemiology, diagnosis, treatment, and prevention of infection, as well as continued areas of uncertainty.

The importance of pertussis in older adults: a growing case for reviewing vaccination strategy in the elderly

Pertussis or whooping cough is increasingly being shown to be a respiratory infection affecting the elderly and a significant percentage of older people infected with Bordetella pertussis experience considerable morbidity and even mortality. However, current knowledge of burden of disease is limited largely to passive surveillance data with little well-designed active surveillance to better ascertain the true burden of pertussis in the elderly, to inform vaccination strategies. The current review aims to identify gaps in knowledge to inform policy considerations relating to pertussis vaccination among the elderly.

Seroprevalence of pertussis among Danish patients with cough of unknown etiology

The common perception that pertussis is only a childhood disease is not correct. Vaccination or infection with Bordetella pertussis provides only short-lived protection against pertussis-and the majority of the population is consequently at risk of contracting pertussis. We evaluated the seroprevalence of pertussis antibodies (IgG against pertussis toxin) in serum samples from 265 Danish patients, aged 8 years and older, with coughs of unknown etiology. Depending on the cutoff chosen, we found that 2.6% to 10.9% of these patients were seropositive for pertussis. Of 178 patients with a reported duration of cough between 2 weeks and 3 months, 3.4% to 12.4% were seropositive for pertussis, indicating recent infection. Our study indicates that B. pertussis infection may be underdiagnosed among older children and adults with coughs in Denmark.

High prevalence of antibody titers against Bordetella pertussis in an adult population with prolonged cough

BACKGROUND

Pertussis is mainly considered as a disease of childhood. However, an increasing number of adults with infection due to Bordetella pertussis is reported in the literature.

METHODS

A retrospective cohort study of patients with a new origin-cough of more than 3 weeks duration who were evaluated by an internal medicine-infectious diseases group practice in Athens, Greece during the period 10/2005-12/2007 was performed; patients underwent serological testing for B. pertussis infection.

RESULTS

Five hundred and fifty-four adult patients underwent B. pertussis serological testing from whom 441 had a single IgM/IgG measurement. The percentage of seropositivity in the IgM/IgG B. pertussis serological testing was 71.5% in the population studied (397/554 patients; for patients who had IgM/IgG B. pertussis serological testing in more than one occasions, only the result of the first IgM/IgG measurement was taken into account for this analysis). For the subset of patients with a single IgM/IgG measurement, the percentage of seropositivity against B. pertussis was 70.7% (312/441 patients).

CONCLUSIONS

B. pertussis infection should be considered as a significant pathogenic infection in a significant proportion of adult patients presenting a new origin-cough of more than 3 weeks duration. In order to reduce the burden of pertussis disease in adults as well as transmission of pertussis in children, booster vaccination is recommended for adolescents and adults.

Comparison of the safety and immunogenicity of concomitant and sequential administration of an adult formulation tetanus and diphtheria toxoids adsorbed combined with acellular pertussis (Tdap) vaccine and trivalent inactivated influenza vaccine in adults

The annual contact for influenza vaccination provides an opportunity to ensure that adults have received other recommended vaccines such as Tdap. Healthy 19-64 year-olds were randomized to receive concomitant administration of Tdap and influenza vaccines or influenza vaccine followed (in 4-6 weeks by) Tdap. 720 participants were enrolled. No clinically relevant between-group differences were observed in the rates or severities of erythema, swelling, or pain at the Tdap injection site. Injection-site pain was the most commonly reported adverse event (66.6% concomitant administration group versus 60.8% sequential administration group); most pain was graded as mild and resolved by day 3. Seroprotection and seroresponse rates for all influenza strains were comparable between the two groups. For diphtheria and tetanus, seroprotection rates and post-vaccination GMTs were non-inferior in the concomitant administration group compared to the sequential administration group. A trend for lower antibody responses to pertussis antigens PT, FHA, and FIM was observed after concomitant administration and, for PRN, this difference failed the non-inferiority criteria. While there is a small diminution in antibody response to tetanus and pertussis antigens, concomitant administration of Tdap and influenza vaccine was well tolerated and immunogenic and may offer practical advantages including convenience, compliance, and cost-savings.

Pertussis immunisation in adolescents and adults –Bordetella pertussisepidemiology should guide vaccination recommendations

Pertussis, or whooping cough, is an infectious disease that is caused by Bordetella pertussis, affects all age groups and is vaccine preventable. Recently, an increase in reported cases of pertussis in adolescents and adults has been noted in many countries despite high immunisation rates in children. Today pertussis outnumbers all other paediatric vaccine-preventable diseases in some countries. This observation can best be explained by an increased awareness of the disease, the availability of new diagnostic tests and, perhaps, suboptimal efficacy of some pertussis vaccines. In general, B. pertussis infections in adolescents and adults are of concern as they are the most important source of transmission of B. pertussis infections to young, unprotected infants. Many studies with diphtheria and tetanus toxoid, acellular pertussis component combination vaccines, specifically designed for use in adolescents and adults, have been performed and excellent tolerability and immunogenicity have been demonstrated. With the availability of two such products, booster doses in adolescents have been introduced in Canada, Austria, Australia, France, Germany and the US, and many other countries are considering similar expansion of their immunisation programmes at present. In addition, universal immunisation of adults (Austria, every 10 years) or targeting high risk groups (e.g., parents of newborns and other care-givers to children; Germany) have been recommended. If lifelong regular booster doses against pertussis were to be recommended and universal implementation was obtained, the authors believe that the morbidity of pertussis and its spread to infants can be dramatically reduced, and it is possible that the circulation of B. pertussis could be eliminated.

Recent developments in pertussis

Pertussis causes nearly 300,000 deaths in children every year. Most deaths take place in developing countries, but the infection remains a priority everywhere. Pertussis vaccination protects infants and children against death and admission to hospital, but breakthrough disease in vaccinated people can happen. In high-mortality countries, the challenge is to improve timeliness and coverage of childhood vaccination and surveillance. In regions with low mortality and highest coverage, pertussis is frequently the least well-controlled disease in childhood vaccination programmes. Some countries have reported a rise in pertussis in adolescents, adults, and pre-vaccination infants, but how much these changes are real or a result of improved recognition and surveillance remains uncertain. In response, several countries have introduced adolescent and adult acellular pertussis vaccine boosters. The effect so far is unknown; assessment is impeded by poor data. Uncertainties still persist about key variables needed to model and design vaccination programmes, such as risk of transmission from adults and adolescents to infants. New vaccination strategies under investigation include vaccination of neonates, family members, and pregnant women.

Bordetella Pertussis infections in vaccinated and unvaccinated adolescents and adults, as assessed in a national prospective randomized Acellular Pertussis Vaccine Trial (APERT)

BACKGROUND

Acellular pertussis (aP) booster immunizations have been recommended for adolescents and older persons to enhance long-term protection and to possibly reduce community transmission of infections.

METHODS

This was a multicenter, randomized, double-blind vaccine trial in which one-half of the subjects received aP vaccine and one-half received hepatitis A vaccine (control subjects). All subjects were observed for almost 2 years for cough illnesses, and all underwent microbiologic and serologic studies for detection of pertussis infection. Immunoglobulin G (IgG) and immunoglobulin A (IgA) antibodies to pertussis toxin, filamentous hemagglutinin, pertactin, and fimbriae 2/3 were measured by enzyme-linked immunosorbent assay in serum samples obtained 1 and 12 months after immunization. Infection rates were determined with a variety of serologic criteria for control and vaccinated subjects. The incidence of prolonged cough illness was ascertained for subjects with and subjects without serologic evidence of infection.

RESULTS

Infection rates among control subjects are particularly representative of those in nonimmunized adults. Among control subjects, 0.4%-2.7% had increases in pertussis antibody of various types and degrees over 1 year, and 20%-46% had prolonged cough illnesses during this interval. Pertussis toxin antibody had the greatest specificity for detecting increases in antibody levels. Asymptomatic infections were approximately 5 times more common than clinical illnesses that met a strict clinical and microbiologic case definition. Relative to control subjects, aP-immunized subjects may have fewer increases in the antibody level (i.e., infections), especially for antibodies to fimbriae 2/3 (an antigen not in the vaccine).

CONCLUSIONS

Pertussis infections in older persons are largely asymptomatic. aP boosters confer protection for adolescents and adults against symptomatic pertussis and likely confer protection against mild and asymptomatic infections, and use of boosters may reduce transmission to others, especially infants.

Mixture model analysis for establishing a diagnostic cut-off point for pertussis antibody levels

Previous studies of pertussis (whooping cough) that have derived diagnostic cut-off points for pertussis antibody levels have assumed a single distribution for antibody levels and have used small sample sizes. In a recent study of 5409 serum samples from the Third National Health and Nutrition Examination Survey (NHANES III), a finite mixture model was developed to examine the distribution of immunoglobulin G (IgG) antibody levels against pertussis toxin (PT), an antigen specific to the Bordetella pertussis bacterium. The mixture model identified three component populations with antibody levels greater than the quantitative assay's lower limit of quantitation (LLQ) and included a point distribution located at or below the LLQ to account for the excess number of antibody values that fell below the LLQ. The mixture model analysis accounted for the NHANES III design. A cut-off point for anti-PT IgG levels was chosen to have a 99 per cent model specificity based on the two overlapping normal distributions assumed for the two component populations with the highest antibody levels. This cut-off point may have a higher diagnostic sensitivity for acute B. pertussis infection than other cut-off points derived by assuming a single distribution for antibody levels.

Shift in the Epidemiology of Pertussis Infection

Pertussis vaccination of young children has been effective in reducing the overall disease burden due to Bordetella pertussis in many countries. However, the disease has not been eliminated, although humans are the only known host of this pathogen. In fact, in some countries, the number of reported cases has increased dramatically from their nadir and epidemics routinely occur. In areas where >80% of children <2 years of age have been vaccinated, the burden of disease has shifted from elementary school-aged children (who are presumably protected by vaccination) to young infants (<6 months of age) and individuals >11 years of age. With the recent availability of acellular pertussis vaccines for older children to adults, consideration of a change in current vaccination policy is necessary in order to provide better disease control.

Environmentally and occupationally acquired diseases in adolescents and adulthood: control of diphtheria, tetanus, pertussis, and poliomyelitis through regular booster vaccinations--a European perspective

Despite the success of childhood vaccination in industrialized countries, diphtheria, tetanus, pertussis (whooping cough), and poliomyelitis (polio) still affect adults and adolescents whose immunity has waned. The resurgence in the 1990s of diphtheria in the area of the former Soviet Union and its subsequent control with immunization campaigns, demonstrates the value of continued adult vaccination. Tetanus cannot be eradicated from the soil reservoir, necessitating routine primary vaccination and regular booster doses to maintain protective immunity. Although Europe has been certified endogenous polio-free since June 2002, polio imported from endemic areas continues to pose a serious threat for vulnerable populations. Booster polio vaccination is required in adolescence and adulthood. Pertussis among adults and adolescents is underestimated, representing a considerable health burden. The consequences can be more serious as this pool of susceptible adolescents and adults is a major source of pertussis transmission to newborns not yet protected by vaccination. The now available acellular pertussis-based combination vaccine covering diphtheria, tetanus, polio, and pertussis, suitable for adults and adolescents, provides the ideal tool for implementing booster immunization programs. Strong recommendations for adolescent and adult boosters are needed to overcome the continued threat of these diseases.

Overview of pertussis: focus on epidemiology, sources of infection, and long term protection after infant vaccination

BACKGROUND

Pertussis, or whooping cough, is a bacterial disease characterized by paroxysmal cough often accompanied by inspiratory whoop and posttussive emesis. Although the introduction of whole-cell pertussis vaccine in the 1940s led to a significant decline in the incidence of pertussis, there has been a gradual increase in reported pertussis cases since 1980. Some of these cases are in infants too young to have received routine pertussis vaccination, and many are in adolescents immunized previously as young children.

METHODS

Based on a literature review, an overview of pertussis is provided, focusing on epidemiology, sources of infection, and trends in incidence patterns, particularly among adolescents. Issues surrounding long-term protection after infant vaccination are also discussed.

RESULTS

The most dramatic increase in pertussis incidence has been among adolescents and young adults. Waning vaccine-induced immunity and refinements in the diagnosis of pertussis have contributed to the rise in the occurrence of pertussis in older age groups. Disease rates in infants have also increased. Determining the source of infection in infants can be challenging, but studies have demonstrated that many infant cases are attributable to infections in adolescent or adult family members.

CONCLUSIONS

Pertussis is on the rise, particularly in adolescents. Booster vaccination of adolescents with less-reactogenic acellular pertussis vaccines appears to be the most logical approach to disease prevention in adolescents and reduced transmission to young infants.

Clinical and economic effects of pertussis outbreaks

BACKGROUND

The reported incidence of pertussis is increasing, especially among the adolescent population. Current outbreak management strategies include investigating cases, contact follow-up, diagnostic testing, and antibiotic prophylaxis and treatment. The cost of these methods is substantial and can be attributed to the mobilization within public health departments to control the outbreaks.

METHODS

Through an extensive review of the literature, the clinical and economic effects of pertussis outbreaks in various nonhousehold settings are discussed.

RESULTS

The reported incidence of pertussis among adolescents and adults in the United States since the early 1980s continues to rise. The challenges of preventing and controlling pertussis outbreaks involve diagnosing pertussis in a timely, accurate, and standardized fashion and understanding the true burden of disease in different age and socioeconomic groups. The economic effects of pertussis have been demonstrated to be significant to individuals and communities, both locally and globally. Costs associated with pertussis often include diagnostic testing, hospitalization, emergency and/or medical office visits, antibiotic and symptomatic treatment, lost work days, and other reductions in productivity. In outbreak settings, increased surveillance, antibiotic prophylaxis, isolation of infected cases, and enhanced communication and education add to the economic burden of this disease. The potential opportunity to apply the use of pertussis booster vaccination to these populations, particularly among adolescents, likely would reduce the occurrence of pertussis and minimize the clinical and economic repercussions of pertussis outbreaks.

CONCLUSIONS

In the near future, it is anticipated that evaluating the effects of a licensed acellular pertussis booster vaccine in persons > or =10 years of age will become routine in pertussis prevention and outbreak-control activities.

Establishment of diagnostic cutoff points for levels of serum antibodies to pertussis toxin, filamentous hemagglutinin, and fimbriae in adolescents and adults in the United States

Numerous reports have documented that serologic methods are much more sensitive than culture for the diagnosis of pertussis in adolescents and adults. However, a standardized serologic test for pertussis is not routinely available to most clinicians, and the serologic test levels or cutoff points correlated with diseases have not been determined. The goal of the present study was to examine the distribution of immunoglobulin G (IgG) levels against three Bordetella pertussis antigens (pertussis toxin [PT], filamentous hemagglutinin [FHA], and fimbria types 2 and 3 [FIM]) and to determine population-based antibody levels for the purpose of establishing such diagnostic cutoff points. Enzyme-linked immunosorbent assays (ELISAs) were performed with sera from >6,000 U.S. residents aged 6 to 49 years who participated in the Third National Health and Nutrition Examination Survey. Mixture models were developed to identify hypothesized exposure groups and establish diagnostic cutoffs. Quantifiable (>20 ELISA units/ml [EU]) anti-FHA and anti-FIM IgG antibodies were common (65 and 62% of individuals, respectively), but quantifiable anti-PT IgG antibodies were less frequent (16%). Given the distributions of antibody levels, an anti-PT IgG level of > or =94 EU was proposed as the diagnostic cutoff point. Application of this cutoff point to culture-confirmed illness in a prior study investigating cough illness yielded a high diagnostic sensitivity (80%) and specificity (93%). A standardized ELISA for anti-PT IgG with a single serum sample appears to be useful for the identification of recent B. pertussis infection in adolescents and adults with cough illness. The PT cutoff point will be further evaluated in prospective studies of confirmed B. pertussis infection.

Potential strategies to reduce the burden of pertussis

Pertussis continues to be a significant cause of morbidity and mortality among nonimmunized young infants. Although the inception of childhood pertussis immunization programs has significantly reduced the occurrence of the disease in children, waning vaccine-induced immunity permits the disease to affect adolescents and adults, who in turn transmit the disease to unimmunized or incompletely immunized infants. The Global Pertussis Initiative brought together experts from 17 countries around the world to evaluate strategies to improve disease control. Seven strategies were considered: (1) universal adult immunization; (2) selective immunization of mothers and close family contacts of newborns; (3) selective immunization of health care workers; (4) selective immunization of child care workers; (5) universal immunization of adolescents; (6) preschool booster at 4-6 years of age; and (7) reinforcement and/or improvement of current infant and toddler immunization strategies. Because immunization programs vary widely from country to country, no single strategy is likely to be appropriate for all. Moreover it would be helpful to have additional data to support the strategies and provide a better understanding of the disease so that new approaches can be monitored effectively. However, certain steps can be taken now to reduce the incidence of pertussis.

Health burden of pertussis in adolescents and adults

Pertussis in adolescents and adults is common, endemic, and epidemic worldwide, and its incidence is reportedly increasing. Although a number of individuals suffer only a mild cough, many others have symptoms typical of pertussis, causing prolonged cough illness, frequent use of health care resources, missed work and a variety of complications. Symptoms experienced by adolescents and adults include sleep disturbance, weight loss, pharyngeal discomfort, influenza-like symptoms, sneezing attacks, hoarseness, sinus pain, headaches and sweating attacks. Even when symptoms are typical of pertussis, the diagnosis is often not considered in adolescents and adults because of a low awareness of the disease in these age groups. Contrary to common perceptions, complications of pertussis, including some that are serious, are not infrequent in adolescents and adults. These include urinary incontinence, rib fracture, pneumothorax, inguinal hernia, aspiration, pneumonia, seizures and otitis media. Despite underreporting, hospitalization of adults and adolescents does occur. Many believe that adolescents and adults are the groups most commonly infected with pertussis and are now the major source of contagion to infants and young children. Because of the considerable health burden, there is a need for improved vaccination strategies to prevent disease in adolescents and adults and to reduce the risk of transmission to vulnerable infants.

The epidemiology of pertussis: a comparison of the epidemiology of the disease pertussis with the epidemiology of Bordetella pertussis infection

In the prevaccine era pertussis epidemics followed a cyclic pattern, with peaks every 2 to 5 years. With the marked reduction of pertussis by vaccination, the same cyclic pattern still occurs. Studies relating to reported pertussis and Bordetella pertussis infection have been reviewed and analyzed. The increase in reported pertussis over the last 2 decades is mainly due to a greater awareness of pertussis and perhaps to the use of several less efficacious vaccines. Studies of prolonged cough illnesses in adolescents and adults reveal that 13% to 20% are a result of B pertussis infection. Serologic studies suggest that the rate of B pertussis infection in adolescents and adults is approximately 2.0% per year. The rate of cough illnesses (pertussis) caused by B pertussis infection in adolescents and adults is between 370 and 1500 per 100,000 population. These data suggest that there are between approximately 800,000 and 3.3 million cases per year in the United States. The coming availability of adolescent- and adult-formulated diphtheria and tetanus toxoids and acellular pertussis vaccines for adolescents and adults and their widespread use should reduce the reservoir of B pertussis disease. It is suggested that a universal program of adolescent and adult boosters would decrease the circulation of B pertussis in these age groups and possibly could lead to the elimination of the organism from the population.

Pertussis immunization in the global pertussis initiative international region: recommended strategies and implementation considerations

Despite widespread immunization programs in most countries, pertussis disease continues to be a threat to public health. In particular, there has been a resurgence of pertussis disease in older children, adolescents and adults, creating a reservoir of infection, which poses a significant threat to infants who are either unimmunized or incompletely immunized. Global Pertussis Initiative participants from Argentina, Australia, Brazil and Japan considered the relative merits of several strategies to reduce the burden of pertussis disease and suggested strategies that might be implemented in these countries. Infants in these countries receive an initial course of 3 doses of vaccine in the first year of life followed by a fourth dose in the second year. Only children in Japan are not given a preschool booster (age 3-5 years). Of the strategies considered, the addition of a preschool booster is therefore a priority in Japan to overcome the problem of waning vaccine-induced immunity to pertussis in school children. Waning immunity also affects adolescents; Australia introduced an adolescent booster in 2003, and the addition of a booster in this age group was suggested for Argentina and Japan. Immunization of new mothers and other close contacts of young infants, such as child care and health care workers, might be appropriate in Australia in the future. Argentina also suggested a future possibility of immunizing health care and child care workers. Obstacles to new immunization strategies include poor access to standardized laboratory diagnostic techniques, inadequate resources to fund new immunization programs, low awareness of pertussis disease in adults and adolescents and inadequate surveillance techniques to assess the full extent of the problems caused by pertussis or the impact new vaccination strategies might have.

Molecular pathogenesis, epidemiology, and clinical manifestations of respiratory infections due to Bordetella pertussis and other Bordetella subspecies

Bordetella respiratory infections are common in people (B. pertussis) and in animals (B. bronchiseptica). During the last two decades, much has been learned about the virulence determinants, pathogenesis, and immunity of Bordetella. Clinically, the full spectrum of disease due to B. pertussis infection is now understood, and infections in adolescents and adults are recognized as the reservoir for cyclic outbreaks of disease. DTaP vaccines, which are less reactogenic than DTP vaccines, are now in general use in many developed countries, and it is expected that the expansion of their use to adolescents and adults will have a significant impact on reducing pertussis and perhaps decrease the circulation of B. pertussis. Future studies should seek to determine the cause of the unique cough which is associated with Bordetella respiratory infections. It is also hoped that data gathered from molecular Bordetella research will lead to a new generation of DTaP vaccines which provide greater efficacy than is provided by today's vaccines.

Diagnosis and management of pertussis

Pertussis is increasing in frequency among children too young to be vaccinated and among adolescents and adults. This increase is due mainly to waning immunity among vaccinated individuals, who become susceptible during adolescence and adulthood and maintain the circulation of Bordetella pertussis. Infants are at highest risk of severe illness requiring hospital admission, complications and death. The clinical presentation in adolescents, adults and vaccinated individuals may be atypical, with paroxysmal cough of short duration or simply a persistent cough. Culture and polymerase chain reaction may be used to identify B. pertussis infection, but their sensitivity is high only in the early phase of the disease. Serologic tests are not standardized for the diagnosis of pertussis, and their clinical application is limited. Erythromycin is still considered in some countries to be the "gold standard" for therapy and prophylaxis; however, azithromycin and clarithromycin seem equally efficacious and are associated with fewer side effects.

Management of acute bronchitis in healthy adults

Acute respiratory infections (ARIs) are the most common infections in humans, accounting for half of all acute conditions each year in the United States. Acute bronchitis episodes represent a significant portion of these illnesses. This article focuses on acute bronchitis in otherwise healthy individuals.

European Sero-Epidemiology Network: standardisation of the assay results for pertussis

A standardisation process was developed in order to compare and harmonize serological results of pertussis toxin (PT) antibody measurements performed by laboratories using different technical procedures for detection. This involved the development of a common panel, of sera by a designed reference centre, the distribution of the panel to each participating laboratory for testing with their routine methods, the comparison of the obtained results to those of the reference centre, and the calculation of standardisation equations by regressing the quantitative results against those of the reference centre. As a cut-off indicative of protection against pertussis has not yet been defined, a particular emphasis was laid upon achieving standardisation of high titre results that would allow epidemiological evaluations based on the estimation of the incidence of recent infections rather than on the traditional approach of determining the population immunity profile. A generally good agreement was achieved between the participating laboratories, all using ELISA procedures very similar in many crucial aspects, and standardisation equations were produced useful to enable inter-country comparison during the next stages of the European Sero-Epidemiology Network (ESEN) project concerning the serological surveillance of immunity to pertussis in Europe.

Pertussis of adults and infants

Bordetella pertussis continues to circulate even in populations where a high vaccine coverage of infants and children is achieved. Cases in adolescents and adults are reported with increasing frequency in many countries. Adults are a reservoir for infections in very young infants, in whom pertussis may be severe and life-threatening. The salient clinical feature of pertussis in adolescents and adults is prolonged coughing, and recognising that pertussis does occur in these age groups is the most important step in its diagnosis. A laboratory diagnosis can be made by bordetella-PCR from nasopharyngeal swabs or secretions and by detection of antibodies, mainly to pertussis toxin; laboratory diagnosis is, however, not well standardised. Vaccination of adolescents and adults is now possible with acellular pertussis vaccines, which are well tolerated, immunogenic, and effective. Adolescent boosters and the vaccination of health-care workers are already included in vaccination calendars in some countries. Vaccine-recommending bodies and national health-care organisations must have locally relevant information on the transmission of pertussis from adults to infants to be able to make decisions on the advisability, feasibility, and priority for booster immunisation against pertussis.

Which strategy for pertussis vaccination today?

Pertussis (whooping cough) remains an epidemic disease responsible for infant and child morbidity and mortality, and is perceived as a serious public health problem. Since the widespread use of whole-cell pertussis vaccines in the 1940s, vaccination programs have varied greatly between countries. National specificity is a function of several factors. The most important are: vaccine efficacy and tolerability;vaccine coverage and distribution; and vaccine acceptance by parents and professionals. During the 1970s, Sweden, England, Wales and Japan provided contrasting examples of the attitude of health authorities to the use of whole-cell vaccines. The increase in pertussis incidence was noted as a consequence of active opposition to this vaccine. The re-emergence of pertussis in the 1990s, in countries with high vaccination coverage and increased incidence of disease in individuals >15 years and <6 months of age, has drawn attention to the role of booster doses of pertussis vaccines and their introduction into regular vaccination programs. The use of acellular vaccines for booster doses for adolescents and adults would seem unambiguous because of their decreased reactogenicity, although the exact schedule has yet to be established. The choice between the two kinds of vaccines is more difficult for primary courses, where safety and efficacy profiles are similar, and the attitude towards acellular vaccines varies from country to country. In this case, the strategy adopted results from the national history of pertussis infection and from the quality of the available whole-cell vaccine. Two contrasting examples are the US, where acellular vaccines were licensed for the primary series in the 1990s, and the UK, where whole-cell vaccines are exclusively used for primary immunization. The changing epidemiology of pertussis, and its local diversification, would suggest that at present it is difficult to define a single worldwide strategy with only one kind of vaccine and one schedule. In order to control pertussis incidence, each country should continue to determine the best national vaccination program established in very close relation to the past and present epidemiological situation and available healthcare resources.

Distribution of pertussis antibodies among different age groups in Japan

We examined the distribution of antibody levels against pertussis toxin (PT) and filamentous hemagglutinin (FHA) among a healthy Japanese population aged from 0 to 77 years. Levels of both antibodies in 1108 serum samples collected in 1994 from nine prefectures were assayed using polystyrene ball ELISA. The ratio of individuals positive (>or=10 ELISA U/ml) for anti-PT and anti-FHA antibodies at ages ranging from 0 to 3 years increased rapidly with the increase in the population vaccinated over three times with acellular pertussis (aP) vaccine. However, the ratio of those positive for anti-PT antibody tended to decrease until 6-8 years of age and to increase again from 9 to 19 years among the vaccinated population, although the ratio of individuals positive for anti-FHA antibody remained constant at 80-100% in children and adolescents over 3 years old. Moreover, positivity for anti-PT antibody was high (>or=50 ELISA U/ml) in some serum samples collected from adolescents and young adults, suggesting recent symptomatic or asymptomatic infection with circulating Bordetella pertussis. On the other hand, 50-60% of infants below 12 months of age was below the detection limit (1.0 ELISA U/ml) for anti-PT and anti-FHA antibodies, and most early infants were not vaccinated for pertussis. Since intermittent circulation of B. pertussis remains among the Japanese population, complete vaccination with aP vaccine for all infants should be highly recommended to prevent pertussis.

Maternal vaccines

Acute lower respiratory illness (LRI) is the leading cause of disease worldwide as measured by disability-adjusted life years. New strategies are necessary to decrease the disease burden that is largely borne by infants. Respiratory syncytial virus is the most important cause of LRI in infants. Lower respiratory illness can be prevented by endowing infants with high levels of neutralizing antibodies from mothers whose antibodies are boosted during pregnancy with a potent subunit vaccine. Another important cause of infant mortality is group B streptococcus sepsis in the neonatal period; maternal immunization with a group B conjugate vaccine could prevent this devastating infection.

A trial of acellular pertussis vaccine in hospital workers during the Cincinnati pertussis epidemic of 1993

The safety and immunogenicity of acellular pertussis (AP) vaccine in outbreak control was determined in a randomized, double-blind, controlled trial. Participants received AP vaccine (n=102), which contained 25 microg of pertussis toxoid (PT) and 3 microg of filamentous hemagglutinin (FHA), or licensed meningococcal vaccine (MN; n=97). Local reactions (pain or tenderness, redness, swelling, and induration) and systemic reactions (fever, sleepiness or lethargy, and irritability) were similar among AP and MN vaccinees. One month after AP vaccination, the geometric mean level of IgG anti-PT was 33.1 microg/mL, with 2-fold increases in 85% of patients and 4-fold increases in 73% of patients; for IgG anti-FHA, the respective values were 34.7 microg/mL, 92%, and 63%. After 6 months of follow-up, no serological evidence of pertussis was seen among symptomatic or asymptomatic subjects. However, recent evidence of Bordetella pertussis infection before immunization was shown. Thus, AP vaccine was safe and immunogenic in adults.

Pertussis is a frequent cause of prolonged cough illness in adults and adolescents

Although pertussis is increasingly recognized as a cause of prolonged cough illness in adolescents and adults, its prevalence is not well established. We evaluated pertussis infection in 442 adolescents and adults > or = 12 years old (mean age, 41.3 years) who had a cough-related illness of 7--56 days' duration. For 4 patients (0.9%), results of nasopharyngeal culture or PCR were positive for Bordetella pertussis; for 10 patients (2.3%), either results of culture or PCR were positive or pertussis antibody titers increased 4-fold. Eighty-eight patients (19.9%) had either laboratory-confirmed pertussis or laboratory evidence of pertussis. These patients had significantly longer duration of cough than did patients without laboratory evidence of pertussis (56 days vs. 46 days), and more of them had vomiting with cough (45.5% vs. 28.5%, respectively). Pertussis is a common cause of prolonged cough illness in adolescents and adults and is frequently associated with other symptoms of whooping cough.

Storage at −3°C for 24 h alters the immunogenicity of pertussis vaccines

The immunogenicity of pertussis antigens in an acellular and a whole-cell triple antigen vaccine used for childhood immunisation was assessed in murine models after storage of vaccines below 0 degree C. Swiss outbred and Balb/c mice received DTPa or DTPw vaccine or placebo. Vaccines were stored at 2-8 degrees C (ideal), or at -3 degrees C for 24 h. Pre and post immunisation IgG responses to pertussis toxin (PT), filamentous haemagglutinin (FHA) and pertactin (PRN) were measured using enzyme immunoassays (EIA). In Balb/c mice, responses to pertactin after receiving adversely stored DTPa were significantly reduced (P = 0.005, difference in GMCs 145.9% [24.6-385.4%]). A reduction in GMC to pertactin was also seen in response to adversely stored DTPw (P = 0.190,224.1% [83.8-599.2%]). Outbred mice receiving adversely stored DTPa had lower IgG antibody responses to FHA than those receiving correctly stored vaccine (P = 0.002,522.2% [26.1-2155.6%]). Outbred mice also had a significantly lower response to FHA after administration of DTPw (P = 0.009,14.0% [3.8-51.9%]). Responses to DTPa in both strains generally were greater than those to DTPw. Storage of pertussis vaccines below 0 degree C appears to alter the immunogenicity of PRN and FHA. Further study is required to determine the effects of such storage on vaccine protective efficacy.

Antibody responses to Bordetella pertussis antigens and clinical correlations in elderly community residents

A serological study to determine the frequency of Bordetella pertussis infection in 100 adults aged >/=65 years was carried out over a 3-year period. Ten serum samples (collected every 4 months) from each subject were examined for IgA and IgG antibodies to the following B. pertussis antigens: pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin, and fimbriae-2. A >/=2-fold titer increase in ELISA units from one time period to the next was considered serological evidence of infection. The rate of serologically defined infection (i.e., in which there was an increase in titer against any antigen) was 19.7 per 100 person-years. With the use of more specific criteria that indicate definite B. pertussis infection (>/=2-fold increase in titer to PT) and probable B. pertussis infection (>/=2-fold increase in titer to PT or >/=2-fold increase to fimbriae-2), the rates were 3.3 and 8.0 per 100 person-years, respectively. Fifty percent of individuals with definite B. pertussis infections had time-associated symptomatology. Antibody patterns over time suggest that antibody to FHA and perhaps to pertactin is stimulated by infections with other organisms, as well as B. pertussis infections. Our data suggest that symptomatic pertussis occurs in elderly individuals. Consideration should be given to immunization of the elderly with acellular pertussis vaccines.

Adult formulation of a five component acellular pertussis vaccine combined with diphtheria and tetanus toxoids and inactivated poliovirus vaccine is safe and immunogenic in adolescents and adults

BACKGROUND

Pertussis is increasingly recognized as an important cause of cough illness in adolescents and adults.

PURPOSE

To evaluate the safety and antibody response to a single dose of an adult formulation of a five component (pertussis toxoid, filamentous hemagglutinin, pertactin, fimbriae 2 and 3) acellular pertussis vaccine (aP) combined with diphtheria and tetanus toxoids (TdaP) and inactivated poliovirus vaccine (TdaP-IPV) in adolescents and adults and to assess the response to a second dose of the acellular pertussis vaccine in a subset of the adults.

POPULATION AND SETTING

The study addressed 1207 healthy participants (736 adults and 466 adolescents) recruited in five Canadian communities.

STUDY DESIGN

In a randomized, observer-blind, controlled clinical trial, adult participants received Td followed at a separate visit by aP, TdaP followed by IPV or TdaP-IPV; adolescents received Td-IPV followed at a separate visit by aP or TdaP-IPV. A subgroup of adults was given a booster of aP 1 month after TdaP.

OUTCOME MEASURES

Antibody titers measured before and 1 month after each immunization; adverse events enumerated at 24 h, 72 h and 8 to 10 days.

RESULTS

The aP vaccine given by itself was associated with adverse events less frequently than were Td, Td-IPV, TdaP or TdaP-IPV vaccines, but reaction rates did not differ significantly among the latter products. The antibody response against Bordetella pertussis antigens was vigorous in all groups, although adults given the TdaP-IPV vaccine had lower antibody titers against filamentous hemagglutinin, pertactin, diphtheria and tetanus antibodies than those given TdaP vaccine. Similarly adolescents given TdaP-IPV had lower antibody titers against pertussis toxin, filamentous hemagglutinin, fimbriae and agglutinins than those given Td-IPV and aP alone. A second dose of acellular pertussis vaccine was not associated with increased adverse events in adults but elicited increased antibody titers over that achieved by a single dose only against pertussis toxin.

CONCLUSIONS

This adult formulation five component aP vaccine given as TdaP-IPV is safe and immunogenic in adolescents and adults and is a candidate vaccine for adolescent and adult immunization programs.

Prolonged afebrile nonproductive cough illnesses in American soldiers in Korea: a serological search for causation

A serological study was undertaken to investigate infections in active-duty United States soldiers with illnesses characterized by prolonged, afebrile, nonproductive coughs. Fifty-four soldiers were enrolled with such illness of >/=2 weeks' duration (case patients) along with 55 well soldiers (control subjects). Serum samples were tested for IgG and IgA antibody to 3 Bordetella pertussis antigens, pertussis agglutinins, IgM antibodies to Mycoplasma pneumoniae, IgM and IgG antibodies to Chlamydia pneumoniae, and IgM antibody to adenoviruses. Forty-six case patients (85%) had evidence of recent infection with Bordetella species, M. pneumoniae, or C. pneumoniae, and many had evidence of mixed infections; there were 27 Bordetella species, 20 C. pneumoniae, and 33 M. pneumoniae recent infections. Fifteen case patients had high titers of IgG or IgA to B. pertussis filamentous hemagglutinin without high titers of antibodies to other B. pertussis antigens, which suggested the presence of cross-reacting antibodies to M. pneumoniae and perhaps C. pneumoniae or unidentified infectious agent or agents. Since illnesses due to Bordetella species, M. pneumoniae, and C. pneumoniae can all be treated with macrolide antibiotics and B. pertussis illness can be prevented by immunization, and since military readiness was affected in 63% of the cases, it seems important to conduct further studies in military populations.