Pertussis seroprevalence in korean adolescents and adults using anti-pertussis toxin immunoglobulin G.

This study was conducted to evaluate age-specific seroprevalence of pertussis in Korea and to formulate a strategy to prevent and reduce the incidence of pertussis. Residual serum samples of healthy adolescents and adults 11 yr of age or older were collected between July 2012 and December 2012, and anti-pertussis toxin (PT) IgG titers were measured using a commercial ELISA kit. We compared the mean anti-PT IgG titers and seroprevalence of pertussis of the six age groups: 11-20, 21-30, 31-40, 41-50, 51-60, and ≥ 61 yr. A total of 1,192 subjects were enrolled. The mean anti-PT IgG titer and pertussis seroprevalence were 35.53 ± 62.91 EU/mL and 41.4%, respectively. The mean anti-PT IgG titers and seroprevalence were not significantly different between the age groups. However, the seroprevalence in individuals 51 yr of age or older was significantly higher than in individuals younger than 51 yr (46.5% vs 39.1%, P = 0.017). Based on these results, a new pertussis prevention strategy is necessary for older adults.

[Serum immunoglobulin IgG subclass distribution of antibody responses to pertussis toxin and filamentous hemagglutinin of Bordetella pertussis in patients with whooping cough]. / Wystepowanie przeciwcial dla toksyny krztuscowej i wlókienkowej hemaglutyniny Bordetella pertussis w poszczególnych podklasach IgG w przebiegu krztusca.

INTRODUCTION: The present study was aimed at determining the IgG subclass distribution against pertussis toxin (PT) and filamentous hemagglutinin (FHA) of Bordetella pertussis in patients with whooping cough. METHODS: The total number of 222 serum samples obtained from patients suspected in clinical investigation for pertussis were tested separately by in-house ELISA for the presence of IgG antibodies to pertussis toxin and filamentous hemagglutinin. The percentage distribution of specific anti-PT and anti-FHA IgG subclass response was calculated only on the basis of group of sera confirmed in the present study as positive for total IgG antibodies (183 sera to PT antigen and 129 to FHA antigen). Paired serum specimens were obtained from 36 patients. Based on the results of determining the level of antibodies in the sera of 40 blood donors, the cut-off limit of serum antibodies for each subclass was set at arithmetic mean plus two standard deviations. RESULTS: Antibodies of IgG1 to pertussis toxin and filamentous hemagglutinin were diagnosed in 151 (82.5%) and 99 (76.7%), IgG2 in 72 (39.0%) and 50 (38.8%), IgG3 in 17 (9.3%) and 43 (33.3%), IgG4 in 55 (30.1%) and 53 (41.1%) serum samples, respectively. There were no significant differences in percentage of sera with IgG1, IgG2 and IgG3 in relation to age of the patients. However, the frequency of occurrence of IgG4 antibodies was highest in the group of the youngest children to the age of 6 years old (61.8% for PT and 68.0% for FHA), and decrease with age, reaching the minimum in the group of patients above 40 years old (13.2% and 4.2% for PT and FHA, respectively). We also found significantly higher frequency of IgG4 to PT and FHA antigens in men than in women. Statistically significant, essential changes in the pattern of IgG subclass during the course of infection were not found. CONCLUSIONS: In conclusion, this study showed that all four subclasses of IgG antibodies to pertussis toxin and filamentous hemagglutinin are produced during whooping cough.

[Serological activity of vaccine and circulating Bordetella pertussis strains].

AIM: To study activity of vaccine and circulating strains of Bordetella pertussis in serological reactions with serum samples from healthy vaccinated children and children with pertussis infection. MATERIALS AND METHODS: One hundred forty-six serum samples from children with pertussis infection as well as 158 samples from healthy vaccinated children aged 3 - 5 years old were studied. Serologic activity of 3 vaccine strains and 7 strains of B. pertussis isolated from patients with pertussis in 2001 - 2005 against sera of children with pertussis infection or vaccinated children was assessed with hemagglutination assay (HA), radial gel immunodiffusion (RGI), and immunoelectrophoresis (IEP). RESULTS: In HA both serum samples of infected and vaccinated children were equally active in agglutination of microbial preparations prepared from vaccine or recently isolated strains of B. pertussis. RGI assay showed that 81 - 84% of serum samples from infected children and 17 -19% of samples from healthy vaccinated children reacted with vaccine strains, and 81 - 85% of samples from infected children and 16 - 20% of samples from healthy vaccinated children reacted with circulating strains: Sera from patients with pertussis formed identical lines of precipitation with vaccine and circulating strains in RGI assay and three types of precipitation arches profile in IEP. Sera from healthy vaccinated children formed identical precipitation arches with vaccine and circulating strains in RGI assay and one type of precipitation arches profile in IEP. CONCLUSION: Antibodies of patients with pertussis were equally active against vaccine and circulating strains of B. pertussis. Antibodies of vaccinated children were also equally active against vaccine and circulating strains although revealed more narrow spectrum of antigens compared to children with pertussis infection.

Establishment of Ph. Eur. Bordetella pertussis mouse antiserum Biological Reference Preparation batches 2, 3 and 4.

A project aimed at establishing replacement batches for the European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP) Bordetella (B.) pertussis mouse antiserum was started in 2013 under the aegis of the Biological Standardisation Programme (BSP) of the European Directorate for the Quality of Medicines & HealthCare (EDQM). This BRP is used for the immunogenicity assay in mice to assess the potency of acellular pertussis (aP) vaccines as described in Ph. Eur. general method 2.7.16. Assay of pertussis vaccine (acellular). In a preliminary phase of the project (referred to herein as BSP129 phase 1) a hyper-immune serum pool was produced in mice using a combined aP vaccine as immunogen. This pool was used to generate 3 freeze-dried candidate (c) B. pertussis anti-mouse serum BRP batches (cBRP2, cBRP3 and cBRP4). After the pre-qualification that showed their suitability as candidate batches, an international collaborative study (BSP129 phase 2) was carried out in order to standardise these 3 batches against the current BRP1 in terms of anti-PT, -FHA, -PRN and -FIM2/3 antibody contents. For the sake of continuity with the standardisation of BRP1, the corresponding WHO standard (1RR 97/642) was introduced as a second reference for the calibration of the 3 candidate BRPs. Eleven laboratories took part in phase 2. Ten of them performed the ELISA method they use routinely for aP vaccine batch release and one laboratory performed the Multiplex Immunoassay (MIA) as an alternative test. Four participants titrated the antibodies against all 5 pertussis antigens, 5 participants determined the antibody content against 3 antigens (PT, FHA, PRN), one participant titrated the antibodies against PT and FHA antigens and one laboratory determined the antibody content for the PT antigen only. Details of all ELISA methods used were analysed to evaluate their impact on the calibration of the cBRPs. The variability of the results in relation to the nature and methodology of the tests appeared rather limited. Discrepant titres of cBRPs were measured depending on the reference used: the use of the 1RR induced an overestimation (in 8 out of 11 laboratories) and a large inter-laboratory variation in the calculated titres. Regardless of the reference used, equivalency between the calculated titres of cBRP2 and cBRP3 was observed, whilst cBRP4 had systematically lower titres for all antibodies against the 5 acellular pertussis vaccine components. Based on these observations, it was decided to establish the candidate BRP batches against BRP1 and to assign the following potencies based on the mean values determined through centrally calculated results of the calibration assays performed by ELISA in BSP129 phase 2: For cBRP2 and cBRP3 Anti-pertussis toxin: 37 ELISA Units (ELU) per vial Anti-filamentous haemagglutinin: 114 ELU per vial Anti-pertactin: 44 ELU per vial Anti-fimbrial agglutinogens (FIM2/3): 25 ELU per vial For cBRP4 Anti-pertussis toxin: 32 ELU per vial Anti-filamentous haemagglutinin: 98 ELU per vial Anti-pertactin 38 ELU per vial Anti-fimbrial agglutinogens (FIM2/3):23 ELU per vial In February 2018, BRP2, BRP3 and BRP4 were adopted by correspondence by the Ph. Eur. Commission.

Seroprevalence of antibodies for pertussis and diphtheria among people leaving or entering China: a cross-sectional study.

INTRODUCTION: Despite high population immunity, pertussis remains one of the leading causes of vaccine-preventable deaths worldwide. The aim of this study was to determine the seroprevalence of IgG antibodies to pertussis toxin (PT) and diphtheria among the adult male population leaving or entering China. METHODOLOGY: Blood samples were obtained from 240 Chinese and 207 African healthy adults that were leaving and entering China, respectively. Serum IgG antibodies against PT (anti-PT IgG) and diphtheria were determined. RESULTS: The mean concentration of anti-PT IgG antibodies was 13.82 IU/mL and 18.11 IU/mL for the leaving and entering populations, respectively. None of the studied Chinese leaving China were seropositive for pertussis. Of the 240 subjects leaving China, 209 (87.1%) had anti-diphtheria antibody concentrations of ≥ 0.1 IU/mL and 31 (12.9%) had antibody concentrations between 0.01 and 0.099 IU/mL. Eleven (5.31%) of the studied Africans entering China had anti-PT IgG antibodies higher than 30 IU/mL and thus were considered seropositive for pertussis. Of the 207 Africans entering China, antibody concentrations of ≥ 0.1 IU/mL were found in 164 subjects (79.2%) while 43 (20.8%) had antibody concentrations between 0.01 and 0.099 IU/mL. CONCLUSIONS: Almost all Chinese adult men leaving China and most African men entering China have very low serum antibody levels of pertussis. Furthermore, the antibody level of diphtheria among these two populations was low among adults. A larger population study is needed to determine whether booster vaccinations against pertussis and diphtheria should be considered for adults in China and also for Africans entering China.

Seroprevalence of IgG antibodies to pertussis toxin in the Slovene population.

BACKGROUND: The use of pertussis vaccines has reduced the morbidity and mortality of whooping cough. Immunity following the natural disease or vaccination is not life-long and reinfections causing an increase of pertussis antibodies can occur. In this study, the distribution of IgG antibodies to pertussis toxin (anti-PT IgG) among different age groups in Slovenia was determined. METHODS: The seroprevalence of anti-PT IgG antibodies to Bordetella pertussis was investigated in 3418 persons (49.1% males). The population under study was stratified into 27 age groups. The serological results were assigned to five groups, according to their titer levels. The geometric mean titers (GMT) were calculated. RESULTS: In 11.5% sera tested, no IgG antibodies to pertussis toxin were detected. High titers (> or =125 U/ml) were confirmed in 2.3% sera. There were no statistically significant differences between age groups in the proportion of antibody levels. Pre-school children from three to five years of age had the lowest anti-PT IgG GMTs (9.6-10.7 U/ml). Vaccinated children (aged from one to two years) and adolescents from 17-18 years of age had the highest GMTs (>20 U/ml). GMTs were not statistically significantly different between males and females. CONCLUSIONS: The study demonstrated an early decline of anti-PT IgG after vaccination. According to the serological profile, school-age children and adolescents have the highest rate of infection. The large proportion of seropositive adults indicates that reinfection with B. pertussis is relatively common.

Serodiagnosis of whooping cough in Belgium: results of the National Reference Centre for Bordetella pertussis anno 2013.

OBJECTIVE: Report on the pitfalls of serodiagnosis of pertussis in Belgium for 2013 by the NRC Bordetella. METHODS: Determine cases of acute infection using an anti-pertussis toxin (PT) IgG antibody ELISA. RESULTS: A total of 2471 serum samples were received. Clinical information on the duration of cough (at moment of blood sampling) is essential for a reliable interpretation of the results. In order to avoid false negative results, 213 samples for which this information was lacking were not tested. For a total of 2179 patients tested, 520 (23.9%) had antibody levels indicative of an acute infection, 261 (12%) samples were diagnosed as positive (indicative of a pertussis infection or vaccination during the last year), 143 (6.7%) samples were classified as doubtful and 752 (34,5%) (35.5%) were diagnosed as negative. The serodiagnosis of pertussis has limited value for the early diagnosis of the disease and PCR analysis on nasopharyngeal swabs is the method of choice during the first 2 weeks and always for young children <1 year old. For sera collected during the first 2 weeks with anti-PT levels below the threshold for acute infection, a second sample collected 2-3 weeks later is needed a definitive diagnosis. For 503 (23.0%) early samples, a second serum sample was requested but not provided. For 85 patients, for whom a second sample was received, 12.9% were eventually diagnosed as having an acute infection. CONCLUSION: In order to generate reliable serodiagnostic results for pertussis, serum samples should preferentially be collected 3 weeks after onset of symptoms.

Prevalence, diagnosis, and disease course of pertussis in adults with acute cough: a prospective, observational study in primary care.

BACKGROUND: Most cases of adult pertussis probably remain undiagnosed. AIM: To explore the prevalence, diagnosis, and disease course of acute pertussis infection in adult patients presenting with acute cough. DESIGN AND SETTING: Prospective observational study between 2007 and 2010 in primary care in 12 European countries. METHOD: Adults presenting with acute cough (duration of ≤28 days) were included. Bordetella pertussis infection was determined by polymerase chain reaction (from nasopharyngeal flocked swabs and sputa) and by measurement of immunoglobulin G antibodies to pertussis toxin (PT) in venous blood at day 28. An antibody titre to PT of ≥125 IU/ml or PCR positive result in a respiratory sample defined recent infection. Patients completed a symptom diary for 28 days. RESULTS: Serum and/or respiratory samples were obtained in 3074 patients. Three per cent (93/3074) had recent B. pertussis infection. Prior cough duration >2 weeks discriminated to some extent between those with and without pertussis (adjusted odds ratio 1.89, 95% confidence interval = 1.17 to 3.07; P = 0.010). Median cough duration after presentation was 17 and 12 days in patients with and without pertussis, respectively (P = 0.008). Patients with pertussis had longer duration of phlegm production (P = 0.010), shortness of breath (P = 0.037), disturbed sleep (P = 0.013) and interference with normal activities or work (P = 0.033) after presentation. CONCLUSION: Pertussis infection plays a limited role among adults presenting with acute cough in primary care, but GPs should acknowledge the possibility of pertussis in uncomplicated lower respiratory tract infection. As in children, pertussis also causes prolonged symptoms in adults. However, pertussis is difficult to discern from other acute cough syndromes in adults at first presentation.

Development and validation of an Australian in-house anti-pertussis toxin IgG and IgA enzyme immunoassay.

AIMS: Although anti-pertussis toxin (PT) immunoglobulin G (IgG) is considered one of the most specific serological markers for Bordetella pertussis infection, there are few commercial kits available in Australia. We aimed to present the process of development, quality control and on-going clinical validation of an anti-PT IgG and IgA enzyme immunoassay (EIA) in use since 1999, and discuss the application of such tests in the diagnosis of B. pertussis infections. METHODS: A total of 1311 serum samples were used during multiple clinical validations from 1998 to 2010. The samples were drawn from healthy adults, children, patients with other respiratory infections, and patients with confirmed pertussis. Assay reproducibility, accuracy and precision criteria conformed to National Pathology Accreditation Advisory Council (NPAAC) guidelines. RESULTS: Using the World Health Organization clinical and/or laboratory definition of a definite case as the comparative standard, sensitivity was 84% [95% confidence interval (CI) 75-93] and specificity was 98% (95%CI: 90-100) for anti-PT IgG. Sensitivity was 72% (95%CI 64-80) and specificity was 98% (95%CI 90-100) for anti-PT IgA. There was minimal background positivity in either healthy adults or children using the established cut-offs. There was no appreciable effect of immunisation or cross reactions with other respiratory pathogens. CONCLUSION: Serological evaluation of various populations enabled the development of an anti-PT IgG and IgA EIA assay which was suitable for the diagnosis of acute infection in convalescent samples from clinically confirmed cases. Repeated evaluations of population-based cut-offs are required for in-house assays to ensure they remain clinically relevant. The subsequent validation of the cut-offs with WHO international standards has been published in a recent prospective study.

Antibody levels against B. pertussis in neonates measured in dried blood spots.

AIM: We designed this study to investigate if immunoglobuline G-Pertussis toxin (IgG-PT) against Bordetella pertussis in umbilical cord blood can reliably be determined in dried blood spots on filter paper (Guthrie) cards. PATIENTS AND METHODS: We prospectively included 129 mothers and their newborns born in a general hospital in the Netherlands. The relation between IgG-PT against B. pertussis from the umbilical cord measured in dried blood spots (Guthrie card) and in serum samples was studied by means of a Bland-Altman graph, using regression analysis to evaluate the level of agreement of both measurement methods. RESULTS: IgG-PT in Guthrie cards show a high coefficient of correlation with IgG-PT in serum samples from the umbilical cord when calibrated against blood spot calibrators (p<0.05). CONCLUSION: Maternal IgG-PT against B. pertussis measured in cord blood applied to Guthrie cards and calibrated against blood spot calibrators show good agreement with measurement of IgG-PT in cord serum. This offers new perspectives for future studies concerning B. pertussis antibodies.

Seroprevalence of Bordetella pertussis antibodies to pertussis toxin among healthy children.

Pertussis or whooping cough is a highly communicable, vaccine-preventable acute respiratory tract disease, caused mainly by Bordetella pertussis. In this study, serosurveillance of IgG antibodies against pertussis toxin was carried out in healthy children, aged 3 months to 12 years, from the multiethnic cities of Islamabad and Rawalpindi, Pakistan. Kruskal- Wallis test was applied to determine the difference among groups. The results showed that the average values of pertussis toxin IgG dropped down significantly with age after getting the first dose in first 2 years (p < 0.001). Therefore, the researchers suggest introduction of booster vaccination with DTaP at second year of life and school going age to reduce the risk of getting B. pertussis infection.

Prospective evaluation of an Australian pertussis toxin IgG and IgA enzyme immunoassay.

Serological diagnosis of recent pertussis infection is an important part of both clinical assessment and epidemiological documentation of this disease. Standardization of serological testing and interpretation remains challenging despite international efforts to improve it. Currently, determining the anti-pertussis toxin (PT) IgG titer is recommended as the most accurate serological test in Europe and the United States, while Australia relies predominantly on measurement of Bordetella pertussis IgA antibody responses. Using B. pertussis PCR and the WHO clinical case definition as reference standards, the diagnostic utility of in-house anti-PT IgG and anti-PT IgA assays was evaluated prospectively in an Australian community-based cohort (n = 327). Patients provided up to four consecutive serum samples to document the kinetics of antibody response and decay. Previously validated cutoffs for positivity were converted to international units by using WHO-approved reference sera. At currently used cutoffs, both anti-PT IgG (>94 IU/ml) and anti-PT IgA (>20 IU/ml) assays had good specificity (80% [95% confidence interval {95% CI}, 68 to 88%] and 87% [95% CI, 77 to 94%]), but anti-PT IgG assay was consistently more sensitive than anti-PT IgA assay across a range of cutoffs (60 to 79% [95% CI, 53 to 84%] versus 41 to 62% [95% CI, 34 to 69%]). The combination of anti-PT IgG and anti-PT IgA assays performed no better than anti-PT IgG assay alone. The anti-PT IgA response in children under 12 years of age was poor. The accuracy of serology was optimal between 2 and 8 weeks after symptom onset. Cutoffs of >94 IU/ml for anti-PT IgG and >20 IU/ml for anti-PT IgA correlated well with recent pertussis infection and were consistent with recent recommendations from the EU Pertstrain group. Anti-PT IgG assay was superior to anti-PT IgA assay as the test of choice for the diagnosis of pertussis from a single sample.