anti-PT IgG Levels Research Articles

Pertussis seroprevalence and related factors in 15-49 years old women in Mersin, Turkey

Abstract Background Pertussis is an acute, contagious respiratory disease with high mortality and morbidity, especially in early infancy. If the mother is immune to pertussis, infants too young to be vaccinated are protected against pertussis infection after birth by maternal immunity. This study aimed to investigate pertussis seroprevalence and associated factors in women aged 15-49 years. Methods The cross-sectional study was conducted on women aged 15-49 years in Mersin city between December 2023 and February 2024. A total of 352 women from family health centres in four central districts of Mersin were included in the study. In this study, anti PT-IgG levels in blood samples were investigated by enzyme-linked immunosorbent assay ELISA method. In the analysis of the data, descriptive statistics, chi-square analysis, and binary logistic regression analysis were used. The results were presented at a 95% confidence interval, at a significance level of p < 0.05. Results Anti-PT IgG seropositivity was detected in 150 (%42.6) of the women. In seven (2%) of women, the anti-PT IgG value was greater than 100, indicating an acute infection. Individuals who did not receive or could not recall having received school vaccinations were found to be 2.18 times more likely to be seropositive than those who had received vaccinations at school. Individuals residing in the same household with a healthcare professional were found to be 1.78 times more likely to be seropositive than those who did not. Conclusions Half of our region’s newborns lack protection from whooping cough. Maternal immunization with pertussis-containing vaccines is crucial. Many countries have safely used such vaccines for years. Replacing Td with Tdap in Turkey’s pregnancy immunization can better shield mothers and newborns from pertussis. Key messages • Maternal immunization is crucial for protecting newborns from pertussis, reducing mortality and morbidity. • Addressing vaccination disparities is vital to ensure community-wide protection against pertussis, saving lives.

Seroprevalence of antibodies against diphtheria, tetanus, and pertussis across various age groups during the post-COVID-19 pandemic period in Chonburi Province, Thailand.

BackgroundLimited data exists regarding population immunity against diphtheria, tetanus, and pertussis in Thailand during the post-COVID-19 pandemic period. This study aimed to evaluate the age-specific seroprevalence of anti-diphtheria toxoid (anti-DT) IgG, anti-tetanus toxoid (anti-TT) IgG, and anti-pertussis toxin (anti-PT) IgG in individuals across diverse age groups in Chonburi province, Thailand following the COVID-19 pandemic. MethodsBetween October 2022 and January 2023, a total of 657 participants from Chonburi Province, Thailand, were included in this study. The participants were categorized into 9 age groups: < 5, 5-10, 11-20, 21-30, 31-40, 41-50, 51-60, 61-70, and > 70 years. Analysis of anti-DT, anti-TT, and anti-PT IgG levels was conducted using commercial ELISA kits (EUROIMMUN, Lübeck, Germany). ResultsOverall, 65.4% of the population had seroprotection against diphtheria (antibody level ≥0.1 IU/mL), while 95.1% had seroprotection against tetanus (antibody level ≥0.1 IU/mL). The 31-40 years age group exhibited the lowest seroprotection for diphtheria (48.9%), and the > 70 years age group had the lowest seroprotection for tetanus (73.3%). The < 5 years age group showed the highest seropositive rate and highest geometric mean titers for anti-PT IgG. On the contrary, the majority of individuals over 11 years of age displayed anti-PT IgG levels below 40 IU/mL. ConclusionsTo prevent diphtheria and pertussis outbreaks in Chonburi province, implementing catch-up vaccination is necessary. Targeted interventions should be deployed to enhance vaccination coverage among the susceptible population.

Seroprevalence of B. pertussis infection and the changes of specific antibody levels in health care workers during the first two years of COVID-19 in Wuhu, China

BackgroundThe reported number of pertussis cases declined after the implementation of COVID-19 prevention and control measures, however, the burden of pertussis among adults in China remains largely unknown. Additionally, the waning of natural antibody level has also rarely been assessed. MethodsA total of 762 healthcare workers (HCWs) who had underwent the health examinations in 2021 and 2022 were included. Serum anti-PT IgG and IgA levels were determined by ELISA. Recent B. pertussis infection was defined as anti-PT IgG ≥100 IU/ml and/or anti-PT IgA ≥10 IU/ml. ResultsIn 2021, the seroprevalence of recent B. pertussis infection was 10.1 %, and those HCWs in outpatient department had a higher percentage (18.6 %), and geometric mean concentration (GMC) (6.3 IU/ml) than those in other departments. This seroprevalence decreased to 2.4 % in 2022, although the difference remained significant. In the 77 subjects with recent B. pertussis infection in 2021, anti-PT IgG was undetectable in 18 cases the following year. Majority (68/76) of the subjects with anti-PT IgA ≥10 IU/ml in 2021 no longer had detected this antibody in 2022. Among 95 pertussis cases, approximately 60.0 % of cases reported no history of cough. Among those with a documented cough history, 36 cases with suspected pertussis courses who had never been diagnosed. Prolonged cough with nocturnal exacerbation (29/38) was the most commonly reported clinical symptom, and whoop was confirmed in six cases. Uroclepsia and syncopes during the cough attacks were reported by three and one subjects, respectively. One case presented with subconjunctival hemorrhage and tensionic purpura during the course. ConclusionsThe results suggested a high prevalence of B. pertussis infection among HCWs. The presence of unrecognized adult pertussis cases and the rapid waning of antibody indicate the need to improve clinical management for suspected pertussis in adults, and to updated immunization schedule after childhood program.

Bordetella pertussis infection following relaxation of COVID-19 non-pharmaceutical interventions in 2021–2023 in Vancouver metropolitan area, British Columbia, Canada

BackgroundWe recently reported a near disappearance of B. pertussis and a decline in anti-B. pertussis antibodies during the peak implementation of Coronavirus disease 2019 (COVID-19) non-pharmaceutical interventions (NPI) in 2021 in British Columbia (BC), Canada. During 2021–2023, incidence of reported B. pertussis cases remained low in BC at < 1/100,000 population. This study determined how serological evidence of B. pertussis changed after the gradual relaxation of NPI between 2021–2023. MethodsRandomly selected blood samples from school staff 25–51 years old (n = 65) were collected yearly between 2021–2023 in the Vancouver metropolitan area, BC, Canada, and tested for anti-pertussis toxin (PT) IgG levels. Serological evidence of B. pertussis infection (thereafter “seroconversion”) was defined as a quantifiable anti-PT IgG levels in subjects with anti-PT IgG levels below lower limit of quantification in the preceding year or a > 4-fold increase in anti-PT IgG levels between two subsequent years. Samples were also tested for anti-diphtheria toxoid (DT) IgG, and similar seroconversion criteria were applied to exclude seroconversion due to vaccination with tetanus-diphtheria-acellular-pertussis (Tdap). ResultsThree subjects met seroconversion criteria for anti-PT IgG between 2021 and 2022 and 9 between 2022 and 2023, yielding a seroconversion rate of 4.6 /100 person-years and 14.9/100 person-years, P = 0.127, respectively. None of the subjects met the criteria for vaccination with Tdap. The geometric mean concentration of anti-PT IgG showed a statistically significant decrease in 2022 compared with 2021, 4.8 IU/mL IU/ml (95 % confidence interval [CI], 3.8–5.9) vs. 6.4 IU/ml (95 % CI, 4.9–8.2; p = 0.001), followed by a statistically significant increase in 2023 compared with 2022 6.5 IU/ml (95 % CI, 4.9–8.5) vs. 4.8 IU/ml (95 % CI, 3.8–5.9; p = 0.0006), respectively. DiscussionSerological evidence of B. pertussis increased between 2022 and 2023 despite low reported cases, which suggests that B. pertussis circulation resumed after relaxing of COVID-19 NPI.

Seroprevalence of tetanus and pertussis antibodies among health care workers in Wuhu, China

ABSTRACT This study aimed to elucidate the seroprevalence of antibodies to tetanus and pertussis among Chinese health care workers. Blood specimens from health care workers were collected during the 2021 annual medical examination at the First People’s Hospital of Wuhu. Commercial ELISA kits were employed to quantify serum IgG antibodies against tetanus toxin (anti-TT IgG) and both IgG and IgA antibodies against pertussis toxin (anti-PT IgG, anti-PT IgA). A concentration of anti-TT IgG exceeding 0.1 IU/ml was deemed seroprotective against tetanus, while concentrations of anti-PT IgG ≥ 50 IU/ml or anti-PT IgA ≥ 15 IU/ml were indicative of a prior pertussis infection. The overall seroprotective rate for anti-TT IgG stood at 10.43% (92/882), with the highest seroprotective rate (13.91%) in the 20–29 age group, followed by the 30–39 age group (10.57%), 40–49 age group (5.80%), and 50–59 age group (5.63%). Eighteen (2.04%) of the studied subjects were positive to anti-PT IgG, and the positive rate in 20–39 age group and 40–59 age group was 1.19% (8/673) and 4.78% (10/209), respectively. Thirty (3.40%) subjects displayed anti-PT IgG levels ≥100 IU/ml and/or anti-PT IgA ≥ 15 IU/ml, suggesting a recent pertussis infection within the preceding year. Over half (503/882, 57.03%) had undetectable anti-PT IgG antibodies. The majority of health care workers in China appear susceptible to tetanus and pertussis, and a significant subset has experienced pertussis infection. The implementation of booster vaccinations against these diseases for Chinese health care workers is recommended.

Evaluation of Pertussis Antibody Levels (Anti-PT IgG-Anti-FHA IgG) and Associated Factors in Maternal and Cord Blood

Pertussis has a very high mortality and morbidity rate in early infancy. There are many strategies to protect babies from pertussis, maternal immunization is one of them. In this study, it was aimed to evaluate pertussis toxin immunoglobulin G (anti-PT IgG) and filamentous hemagglutinin immunoglobulin G (anti-FHA IgG) levels of pertussis antibody in maternal and cord blood samples and also to evaluate the factors that may be associated with maternal antibody positivity. This descriptive study was conducted between 1 July and 31 October 2020. In the study, anti PT IgG and anti-FHA IgG levels were investigated by enzyme-linked immunosorbent assay (ELISA) method in 154 maternal and 154 cord blood samples. Microbiological analyzes were performed in Hacettepe University Faculty of Medicine Central Laboratory and results of 10 IU/mL and above were considered positive. Factors that could affect antibody positivity were questioned with the data collection form. "Package for Social Sciences (SPSS)" package program version 25.0 was used for statistical analysis of the data. Chi-square and Fisher's exact tests were used for statistical analysis of categorical variables. Continuous numerical variables were analyzed with the Pearson correlation test. Logistic regression analysis was used to evaluate the factors affecting positivity. The natural logarithm of the continuous variables was taken to ensure their conformity to the normal distribution, and conformity to the normal distribution was evaluated with the Kolmogorov-Smirnov test. The results were presented at a 95% confidence interval, at a significance level of p<0.05. The mean age of the mothers included in the study was 30. Of newborn babies, 52.6% were girls and 98.7% had normal birth weights. Of deliveries, 95.5% were term and 82.5% were cesarean section. Anti-PT IgG positivity and anti-FHA IgG positivity in maternal blood were 18.8% and 48.1%, respectively. Anti-PT IgG and anti-FHA IgG positivity in cord blood samples were 38.3% and 55.8%, respectively. Anti-PT IgG positivity was 2.6 times higher in mothers who had healthcare worker relatives compared to those who did not. Anti-FHA IgG positivity was 3.2 times higher in mothers aged 25 and younger than in mothers aged 26- 35. In addition, mothers aged 36 and over were 4.4 times more anti-FHA IgG positive than the mothers aged 26-35. Anti-FHA IgG antibody positivity was found 7.3 times more in those living in extended families than those living in nuclear families. Anti-PT IgG and anti-FHA IgG levels in maternal and cord blood samples were highly positively correlated. Mothers in the study had low pertussis antibody levels, indicating that newborns are at risk for infection. Maternal immunization with pertussis-containing vaccine is the most appropriate and cost-effective strategy to protect the newborn against pertussis. Many countries have been using pertussis-containing vaccines in maternal immunization safely for many years. Replacing the tetanus-diphtheria vaccine (Td), which is included in the routine pregnancy immunization program in Türkiye, with tetanus-diphtheria-pertussis (Tdap) may be appropriate to protect the mother and newborns from pertussis infection.

Pertussis immunisation during pregnancy: Antibody levels and the impact of booster vaccine

Pertussis (whooping cough) is a highly infectious disease caused by Bordetella pertussis. Mothers lacking adequate immunity and contracting the disease represent the biggest risk of transmission to new-borns, for which the disease is often a threat. The aim of the study was to estimate the frequency of pertussis susceptibility among pregnant women, in order to point out the need for a vaccine recall during pregnancy, and to evaluate the antibody response in already vaccinated women. A cross-sectional observational study was conducted in the blood test centre of “St. Anna” Obstetrics and Gynaecology Hospital in Turin (Piedmont, Italy). Eligibility criteria included pregnant women coming to the centre for any blood test, aged 18 or above and with gestational age between 33 and 37 weeks at the moment of the blood draw. The data collection was carried out from May 2019 to January 2020 and the concentration of anti-Pertussis Toxin (anti-PT) IgG was measured through the Enzyme-Linked Immunosorbent Assay (ELISA) technique. Two-hundred women (median age 35) were enrolled: 132 (66%) had received at least one dose of pertussis vaccine, 82 of which during pregnancy. Recently vaccinated women had significantly higher antibody titres (even 12–15 times as high) compared to those vaccinated more than 5 years before or never vaccinated at all (p < 0.0001). Moreover, 95.1% of recently vaccinated women had anti-PT IgG levels above 10 IU/ml, and 85.4% above 20 IU/ml, while the same proportions were as low as 37% and 21% (respectively) in the group of women not vaccinated in pregnancy. This study confirmed that the vaccination is greatly effective in ensuring high antibody titres in the first months after the booster vaccine, with considerable differences in anti-PT IgG compared to women vaccinated earlier or never vaccinated at all, and therefore vaccinating pregnant women against pertussis still represents a valuable strategy.

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 20-29years (N=3976) and 30-39years (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 13.6IU/mL. The proportion of samples with anti-PT IgG ≥100IU/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 <100IU/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 20-39years, despite well-established vaccination programs in Europe.

Determination of serum neutralizing antibodies reveals important difference in quality of antibodies against pertussis toxin in children after infection

ObjectivesTo determine neutralizing antibodies to pertussis toxin (PTNAs) in children with suspected pertussis and to compare results of PTNAs and anti-PT IgG antibodies. Methods172 hospitalized children with suspected pertussis were included. Pertussis was confirmed by culture, PCR and/or serology. PTNAs were determined by Chinese hamster ovary (CHO) cell assay. ResultsA correlation between titers of PTNAs and anti-PT IgG levels was noticed in 172 patients (Spearman R = 0.68, P < 0.001). Subjects with same concentrations of anti-PT IgG antibodies could have different titers of PTNAs and the maximum difference observed reached to 1024 times in ELISA-confirmed patients. Moreover, subjects with same titers of PTNAs could have different concentrations of anti-PT IgG antibodies. ConclusionsOur results indicated that in some children high concentrations of anti-PT IgG antibodies do not always mean effective PTNAs induced after infection, stressing the importance of detecting PTNAs after infection and vaccination.Clinical trial registry: Not applicable.

Pediatric hospital healthcare workers and pertussis; a seroprevalence study.

This study aimed to assess pertussis seroprevalence among healthcare workers (HCWs) of a university children`s hospital and to determine their opinions on whether to get the pertussis vaccine booster dose in adulthood. This cross-sectional study was carried out between January 2018 and March 2019. Data recording forms were filled by the face to face interview method. Anti-pertussis toxin IgG (Anti-PT IgG) antibody levels were determined quantitatively from the serum samples using a commercial enzyme-linked immunosorbent assay (ELISA) kit. Anti-PT IgG results were interpreted according to World Health Organization (WHO) recommendations. Of the 169 HCWs included in the study, 67 (39.6%) were seronegative and susceptible to pertussis. Seropositivity was significantly higher among HCWs who worked 40-80 hours per week. Thirty-six (21.3%) HCWs had high anti-PT IgG levels, indicating recent infection in the past few years. High-level positivity was significantly more common among HCWs using macrolide antibiotics due to prolonged cough. Anti-PT IgG levels of three (1.8%) were compatible with acute infection and they were not followed up with suspicion of whooping cough and were not isolated. While 125 (74.0%) of the participants said they could get the pertussis vaccine booster dose, only three (1.8%) had done so. The fact that 39.6% of HCWs were seronegative, emphasized the need for the pertussis booster dose. More than 20% of HCWs have had the acute infection without pertussis diagnosis in the past few years. Adult vaccination awareness in HCWs has not yet created a change in behavior. The high rate of seropositivity in macrolide users also shows that we cannot prevent its spread despite treatment. These findings highlight the fact that pertussis can occur in adult age groups and that eradication cannot be achieved without effective adult immunization and surveillance.

Impact of Vaccine Schedule Change on Pertussis Epidemiology in France: A Modelling and Serological Study

Background: In 2013, France modified its pertussis vaccination schedule to remove one dose at 3 months of age and change the age of the booster dose from 16 to 11 months. We aimed to assess the subsequent impact on pertussis epidemiology in France. Methods: We analysed the PCR test results of nasopharyngeal swabs (N=7493) collected from symptomatic outpatients aged 2-20 years old between 2012 and 2019 in France. We developed a Poisson regression model in which the number of positive cases by year and age depended on the year, age group, population size of each age group and a proxy of waning immunity that could vary with vaccine schedule. We also compared the anti-pertussis toxin (PT) antibody levels of 315 children born before and after the vaccine schedule change. Findings: The model that best fitted the 2012-2018 epidemiological data supported a faster waning of immunity following vaccination with the new vaccine schedule. Four years after vaccination, the risk of developing pertussis was 2.1 (95% CI, 1.7-2.2) times higher for children vaccinated according to the new schedule than those vaccinated according to the previous schedule. The model correctly predicted the age distribution of cases in 2019. Anti-PT IgG levels were significantly lower in children born after implementation of the new schedule, compared to children born before. Interpretation: A shorter-lived protection induced by the 2/4+11 vaccine schedule recommended in France since 2013 is associated with an increase of pertussis cases in 2-5-year olds. Funding Statement: This project was funded by the INCEPTION interdisciplinary project at Institut Pasteur, “Understanding whooping cough resurgence in Europe by combining genomic, epidemiological and sociological approaches” (French Government Investissements d’Avenir grant ANR-16-CONV-0005). This work received financial support from the French Government’s Investissement d’Avenir program, Laboratoire d’Excellence ‘Integrative Biology of Emerging Infectious Diseases’ (grant n_ANR-10-LABX-62-IBEID). Institutional support was provided by Institut Pasteur and Sante publique France. Declaration of Interests: None to declare. Ethics Approval Statement: The data collection received approval by French supervisory ethics authority (CNIL, n°1474593), and was approved by the local Institutional Review board (N° 2020 1028160733). All data processing and storage comply with the General Data Protection Regulation (GDPR) and ethical standards of the National Research Committee. This study was conducted in accordance with the Helsinki Declaration, with informed consent obtained from each patient’s guardians.

Multiplex Point-of-Care Tests for the Determination of Antibodies after Acellular Pertussis Vaccination.

Most of the current serological diagnosis of pertussis is based on pertussis toxin (PT) IgG antibodies and does not differentiate between vaccination and infection-induced antibodies. PT is included in all of acellular pertussis vaccines available in the world. Multiplex testing of non-vaccine antigen-related antibodies has the potential to improve the diagnostic outcome of these assays. In this study, we developed a quantitatively spatial multiplex lateral flow immunoassay (LFIA) for the detection of IgG antibodies directed against PT, pertactin (PRN), and filamentous hemagglutinin (FHA). The assay was evaluated with serum samples with varying anti-PT, anti-PRN, and anti-FHA IgG levels and the result was compared to those obtained with standardized ELISA. The developed assay showed good specificity with PT and PRN antibodies and semiquantification throughout the antigen combinations. This exploratory study indicates that the multiplex LFIA is specific and sensitive, and a similar test platform with alternative antigens could be suitable for new type of pertussis serology.

Seroprevalence of Bordetella pertussis antibodies and anti-pertussis antibody response after a single dose of reduced-antigen combined diphtheria, tetanus, and acellular pertussis vaccine (Tdap) in pregnant Thai women

BackgroundMaternal immunization with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) has recently been implemented to prevent infant pertussis. Tdap is still not routinely recommended in Thailand, and there are limited data to support or challenge this strategy. ObjectivesThe primary aim was to determine the seroprevalence of anti-pertussis toxin antibodies (anti-PT IgG) among pregnant Thai women. The secondary aims were to evaluate antibodies response after Tdap vaccination between seronegative and seropositive mothers and to compare the different antibody titers at delivery among seropositive mothers who received Tdap to those who received tetanus-diphtheria vaccine (Td). MethodsThis randomized clinical trial was conducted during April 2018 to April 2019 at Siriraj Hospital, Bangkok, Thailand. A total of 129 pregnant women were included. Paired blood samples for anti-PT IgG levels were obtained during the first antenatal visit and at delivery. A baseline cut-off value of <5 IU/ml indicated seronegativity. There were 29 exclusions from the original 129 enrollment. All seronegative participants (n = 69) received Tdap, while the seropositive group were randomized 1:1 to receive either Tdap (n = 18) or Td (n = 13) during 27–36 weeks’ gestation. The antibody levels from both sera were compared between groups. ResultsThe seroprevalence of maternal anti-PT IgG was 33.3% (43/129). There was no significant difference in the increment of antibody levels after Tdap vaccination between the seronegative and seropositive groups (30.2 vs. 42 IU/ml; p = 0.183). Among seropositive groups, all Tdap recipients had increased antibody titers at delivery, while all Td recipients showed waning of immunity throughout gestation. (42 IU/ml vs. −7.4 IU/ml; p < 0.001). ConclusionMost pregnant Thai women have seronegative against pertussis. Most seropositive mothers had initial low antibody titers and their immunity significantly decreased before delivery. Our findings highlight the need for universal pertussis immunization in pregnancy regardless of individual baseline immunity.

Assessment of IgA anti-PT and IgG anti-ACT reflex testing to improve Bordetella pertussis serodiagnosis in recently vaccinated subjects

ObjectivesQuantifying IgG antibodies to pertussis toxin (PT) is the most specific and sensitive method for the serodiagnosis of a Bordetella pertussis infection. Since PT is a component of acellular pertussis vaccines, anti-PT IgG is also induced by vaccination, precluding pertussis serodiagnosis based exclusively on anti-PT IgG in recently vaccinated subjects. Here, we aim to identify additional B. pertussis-specific serological markers that can discriminate between infection and recent vaccination. MethodsThe clinical usefulness of measuring IgA directed to the vaccine antigen PT and IgG directed to non-vaccine antigens (Fim2/3, LPS, ACT, CatACT) was evaluated in nine well characterized subject groups, aged 10–89 years (n = 390). Serum anti-PT IgG levels (>125 IU/mL) served as an indicator for a recent B. pertussis infection. Comparing symptomatic pertussis-infected subjects (n = 140) with recently vaccinated, non-infected subjects (n = 100) revealed the optimal cut-off, accuracy, sensitivity and specificity for each single parameter. ResultsFor pertussis diagnosis in recently vaccinated subjects, the measurement of anti-PT IgA (cut-off 15 IU/mL) and anti-ACT IgG (cut-off 15 U/mL) resulted in accuracies of 95% (91.5–97.1) and 87.5% (82.7–91.1), sensitivities of 92.9% (87.4–96.0) and 83.6% (76.5–88.8) and specificities of 98% (93.0–99.4) and 93% (86.3–96.6), respectively. Comparing anti-PT IgA levels between the youngest (10–19 years, n = 38) and oldest (70–89 years, n = 17) age groups revealed an age-dependent increase in antibody levels in pertussis-infected subjects (p < 0.0001). ConclusionsReflex testing of anti-PT IgA and anti-ACT IgG improves pertussis serodiagnosis in recently vaccinated symptomatic subjects with elevated anti-PT IgG levels. Furthermore, both markers can discriminate between vaccination and recent infection in pertussis serosurveillance studies.

Seroprevalence of diphtheria and pertussis immunoglobulin G among children with pneumonia in Ji\u2019nan, China

BackgroundVaccination is still one of the most important methods to control and prevent childhood infections including diphtheria and pertussis. This study evaluated the level of diphtheria (DT) and pertussis (PT)-related antibodies among children with pneumonia in Ji’nan, China.MethodsA total of 484 sera of children from 1 day to 13 years of age were collected from 2014 to 2015 in Ji’nan. Children with recent history of pertussis were excluded from this study. Anti-DT and PT IgG concentrations were measured by ELISA (Euroimmun, Lübeck, Germany).ResultsOf the 484 subjects tested, the overall positivity rate of anti-DT IgG (≥0.1 IU/ml) was 48.97%, and the highest positivity rate of anti-DT IgG (68.55%) and proportion with long term protection (23.27%) were observed in children aged 6 m- < 3 y. For anti-PT IgG, 334 subjects (69.01%) had anti-PT IgG levels below the lower limit of detection (5 IU/ml). Even with detectable anti-PT antibodies, the majority (115/150, 76.67%) of them had antibody levels of 5- < 40 IU/ml. The highest proportion of subjects with detectable anti-PT IgG (≥5 IU/ml) was observed in children aged < 6 m (44.36%), then the proportion continually decreased to 15.0% at 3 y- < 6 y (χ2 = 24.05, p < 0.0001). The highest positivity rate (≥40 IU/ml) was only 8.27% in children aged < 6 m. Subjects with an anti-PT IgG ≥100 IU/ml were observed in all the groups and there were no significant differences in the proportions of subjects with a level ≥ 100 IU/ml among these age groups (χ2 = 2.572, p = 0.4624). A total of 5 subjects had anti-PT IgG ≥100 IU/ml (≥1 years post pertussis vaccination) which was considered to be indicative of a recent pertussis infection.ConclusionsWe demonstrated low antibody levels and protection against pertussis in our study population. The anti-PT IgG maintained a low level throughout all age groups, and even no immune responses were observed after the basic immunization and booster. Our study supported the need to reevaluate the immune response of DTP vaccine which was used in Shandong province after 2010.

A rapid lateral flow immunoassay for serological diagnosis of pertussis

Current serological diagnosis of pertussis is usually done by ELISA. However, the ELISAs are often central-laboratory based, require trained staff and have long turnaround times. A rapid point-of-care (POC) assay for pertussis serology would aid in both diagnosis and surveillance of the disease. While lateral flow immunoassays (LFIA) are simple to use and ideal for point-of-care diagnostics, they were limited to qualitative assays until recently. In this study, we developed a quantitative LFIA with fluorescent Eu-nanoparticle reporters for the detection of anti-pertussis toxin (PT) IgG. The assay was evaluated by testing 198 serum samples with varying anti-PT IgG levels and the result was compared to those obtained with standardized anti-PT IgG ELISA. At the diagnostic cutoff of 100 IU/mL in ELISA, the LFIA had a concordance of 92% with the ELISA, with a specificity of 96% [95% confidence interval (CI): 89–99%] and a sensitivity of 88% [CI: 77–94%]. The developed LFIA has a turnaround time of one hour and requires only a simple manipulation by the user and an instrument for the quantitative detection of the signal. We conclude that the LFIA is specific and sensitive for serological diagnosis of pertussis and is suitable for a POC test.

Seroprevalence of Bordetella pertussis antibodies in adults in Hungary: results of an epidemiological cross-sectional study

BackgroundPertussis (whooping cough) is well known to be underreported, particularly among adults, who can act as an infectious reservoir, potentially putting susceptible newborns at risk of serious illness. The purpose of this study was to estimate the seroprevalence of pertussis in adults in Hungary.MethodsThis epidemiological, cross-sectional study was conducted in adults in five general practitioners’ practices in Hungary. Serum anti-pertussis toxin immunoglobulin G (anti-PT IgG) antibody levels were analyzed using enzyme-linked immunosorbent assay. Sera were classified following manufacturer’s instructions as: strongly indicative of current/recent infection (≥1.5 optical density [OD] units); indicative of current/recent infection (≥1.0 OD units); seropositive (>0.3 OD units); or seronegative (≤0.3 OD units). Logistic regression was performed to describe the associations between seroprevalence and various characteristics.ResultsBetween 24th April 2014 and 24th April 2015, 1999 adults (60.6% female; mean age 47.4 ± 17.7 years) were included in the analysis. A total of 14.8% were seropositive for anti-PT IgG, 1.1% had a level indicative of current/recent infection, and 0.1% had a level strongly indicative of current/recent infection. Logistic regression showed significant relationships between increased rates of seropositivity and: age ≥60 years (odds ratio [OR], 1.97; 95% confidence interval [CI], 1.39–2.80; p = .0002) or 18–29 years (OR, 1.67; 95% CI, 1.13–2.46; p = .0094) vs. 45–59 years; former smoker (OR, 1.46; 95% CI, 1.08–1.97; p = .014) or current smoker (OR, 1.38; 95% CI, 1.01–1.89; p = .045) vs. never smoker; and male (OR, 1.30; 95% CI, 1.01–1.68; p = .041) vs. female. Also, between increased rates of probable current/recent infection and current smoker (OR, 7.50; 95% CI, 2.32–24.31; p = .0008) or former smoker (OR, 4.07; 95% CI, 1.21–13.64; p = .023) vs. never smoker.ConclusionsApproximately 85% of the adults studied were seronegative and therefore susceptible to pertussis infection. Approximately 1% had anti-PT IgG levels indicative of current/recent pertussis infection, which could potentially be transmitted to susceptible young infants. Vaccination of adults is a key way to indirectly protect infants.Trial registrationClinical Trials.gov NCT02014519. Prospectively registered 12 December 2013.

Seroprevalence of Bordetella pertussis specific Immunoglobulin G antibody levels among asymptomatic individuals aged 4 to 24years: a descriptive cross sectional study from Sri Lanka.

BackgroundIn Sri Lanka pertussis continues to circulate in the community and cases among adolescents and adults have been reported despite 95% coverage of the four dose pertussis vaccination during early childhood. Waning of immunity following natural infection or immunization may contribute to the persistent circulation. An adolescent booster dose is not included in the national immunization schedule of Sri Lanka, although this is routine practice in many countries. Therefore information on immunity to pertussis in the adolescent group is needed prior to considering vaccination schedule changes.MethodsThe quantitative determination of specific Immunoglobulin G antibodies to Bordetella pertussis toxin was done using a commercially available validated ELISA method. The antibody values were categorized into groups according to the interpretive criteria provided by the manufacturer. The values were <55 IU/mL, negative; 55–<60 IU/mL, borderline; 60–125 IU/mL, positive; >125, strongly positive respectively. Sera of 385 asymptomatic individuals aged 4 to 24 years admitted to surgical units of Lady Ridgeway Hospital, Colombo and Colombo South Teaching Hospital were used for the study. Mann-Whitney U and Kruskal-Wallis tests were used in analysis of results and p ≤0.05 was considered as statistically significant. Details of epidemiological variables were collected using a questionnaire and correlation with significant levels of pertussis antibodies was determined.ResultsMedian age of the study population was 12 years with 212 (55.1%) females. The median anti PT antibody level was 3.31 IU/mL and 352 (91%) had anti PT levels ≤55 IU/mL. Median of anti PT levels were 3.18 IU/mL for 4–7 years, 1.43 IU/mL (IQR 0.336–6.27) for 8–11 years, 4.28 IU/mL (IQR 0.978–13.39) for 12–15 years, 6.14 IU/mL for 16–19 years and 4.89 IU/mL for 20–24 years and the differences were statistically significant (p = 0.000). Females (p < 0.003) and those having a sibling aged ≥12 years (p = 0.017) had significantly higher anti PT levels.ConclusionsThe majority of the study population, especially 8 to 11 year age group had low anti PT IgG levels. The higher antibody titers in the 12–15 year age group seem to indicate infection in early adolescence. A booster dose of acellular pertussis vaccine need to be considered.

PO-0260c Pertussis Epidemiology In Izmir, Turkey.

<h3></h3> Pertussis (whooping cough) is a highly contagious, life-threatening, vaccine-preventable respiratory infection. Adults can infect infants who have not completed their primary immunization schedule. Besides, the infection can be asymptomatic among adults so that the reported cases of pertussis reflect only a fraction of the actual number of the patients in Turkey. The aim of this study is to determine the antibody levels against B. pertussis toxin (PT) and filamentous heamagglutinin (FHA) in ages from 6 months to ≥60 years in Izmir, Turkey. The study population consisted of 400 healthy subjects. A cluster of sample design developed by EPI of the World Health Organization was carried out for the selection of the study population. Anti-PT and anti-FHA levels were tested by in-house ELISA in Public Health Institution of Turkey. Anti-PT IgG levels of &lt;10 EU/ml, ≥10 EU/ml and ≥100 EU/ml were accepted as non-immun, immune and possible acute/recent infection, respectively. Of the study population 8.5% had &lt;10 EU/ml, 68.2% had 10–100 EU/ml, and 23.3% had ≥100 EU/ml anti-PT IgG antibodies. According to anti-PT IgG antibody levels 23.7% of the cases were correlated with possible acute/recent infection. The incidence of possible acute/recent infection (≥ 100 EU/ml anti-PT antibodies) was highest among 10–14 and 20–29 years old. The incidence was lowest (18.9%) among 5–6 years old and increased in the school age and was highest (34.3%) among 15–19 years old. Although high infant pertussis vaccination coverage in Turkey, our results showed that, pertussis is endemic, particularly in adolescent and adults. Adolescent and adults can be a major reservoir for the disease who haven’t completed their primary immunization.

Anti-pertussis antibody kinetics following DTaP-IPV booster vaccination in Norwegian children 7–8 years of age

At the age of 7–8 years a booster of diphtheria, tetanus, acellular pertussis and polio vaccine is recommended for children in Norway. In this cross-sectional study we have analysed the antibody levels against pertussis vaccine antigens in sera from 498 children aged 6–12 years. The purposes of this study were to investigate the duration of the booster response against the pertussis vaccine antigens pertussis toxin (PT) and filamentous haemagglutinin (FHA); to determine the presence of high levels of pertussis antibodies in absence of recent vaccination; and to analyse how booster immunisation may interfere with the serological pertussis diagnostics. Prior to the booster the IgG antibody levels against PT revealed a geometric mean of 7.3IU/ml. After the booster the geometric mean peak anti-PT IgG response reached to 45.6IU/ml, followed by a steady decline in antibody levels over the next few years. The IgG anti-FHA levels followed the anti-PT IgG profiles. Three years after the booster the geometric mean IgG levels were only slightly above pre-booster levels. Prior to the booster 44% of the sera contained ≤5IU/ml of anti-PT IgG compared to18% 3 years after and 30% 4 years after the booster. When recently vaccinated children were excluded, 6.2% of the children had anti-PT IgG levels above 50IU/ml which may indicate pertussis infection within the last 2 years. This study indicates that the currently used acellular pertussis vaccines induce moderate immune responses to the pertussis antigens and that the antibodies wane within few years after the booster. This lack of sustained immune response may partly be responsible for the increased number of pertussis cases observed in this age group during the last years.