Number Of Pertussis Cases Research Articles

PERTUSIS - CURRENT SITUATION

Pertussis, or whooping cough, is a contagious acute respiratory infection caused by the bacterium Bordetella pertussis. Before the widespread immunization, pertussis was one of the most common infectious causes of morbidity and death. Despite widespread immunization, the pathogen continues to circulate in the population with cyclical outbreaks. Recent data from the Institute of Public Health of Serbia "Dr Milan Jovanović Batut" for the territory of the Republic of Serbia reveals a significant rise in pertussis cases in the last year, which creates a need for careful analysis of the current epidemic. The aim of our study was to show the current epidemiological situation related to pertussis illness, along with an analysis of patients hospitalized at the Children's Hospital for Pulmonary Diseases and Tuberculosis, Clinical Hospital Center "Dr Dragiša Mišović" from August 2023 to February 2024, who were laboratory confirmed with B. Pertussis infection. During this period, 23 patients were hospitalized with confirmed B. Pertussis infection. The laboratory method for isolating the bacterium was a nasopharyngeal swab that was sent for PCR analysis. The average age of hospitalized children was 4.6 months, with the majority being 2 months old. The youngest infants were 1 month old, while the oldest patient was 35 months old. B. Pertussis infection was confirmed in children who were either not vaccinated or were incompletely vaccinated due to their age. The most commonly associated conditions with B. Pertussis infection were acute bronchiolitis and pneumonia, with SARS COV-2 virus isolated in two cases. Based on the results of our analysis and data from the literature, we observed an increase in the number of pertussis cases. Although vaccination has significantly contributed to reducing the incidence of pertussis, this analysis highlights challenges and the need for continued following of the epidemiologic situation. Additionally, it is crucial to consider factors contributing to the resurgence of the epidemic to develop more effective strategies for disease control and prevention.

Cost-effectiveness analysis of pertussis booster vaccination for adolescents in Japan

IntroductionIn Japan, the introduction of a fifth diphtheria–tetanus–acellular pertussis (DTaP) vaccination has been considered, and adolescents aged 11–12 years old who are currently receiving the diphtheria–tetanus (DT) vaccine are one candidate group. We analyze the cost-effectiveness of replacing the DT vaccine with the DTaP vaccine for 11-year-old adolescents and investigate the indirect effect of vaccinated adolescents on unvaccinated infant siblings. We undertake two analyses using high- and low-morbidity pertussis cases, and based on the results, present suggestions for pertussis prevention in the post-COVID-19 pandemic era. MethodWe used the number of pertussis cases in 2019 as the high-morbidity case and the average number of cases in 2020–2021 as the low-morbidity case, and evaluated the incremental cost-effectiveness ratio (ICER) of the DTaP strategy to the DT strategy based on quality-adjusted life years (QALYs). The economic model contained adolescent and infant sub-models. The indirect effect for infants was considered as the probability of unvaccinated infants avoiding pertussis infection from their vaccinated siblings. ResultsThe ICER from the payers’ perspective was Japanese yen (JPY) 4,254,515 per QALY gained in the high-morbidity case and JPY 62,546,776 per QALY gained in the low-morbidity case. The sensitivity analysis showed that the utility of pertussis had the greatest impact on the ICER, with a 60.58% and 0% probability that the ICER was less than JPY 5 million per QALY gained in the high-morbidity case and low-morbidity case, respectively. ConclusionThe cost-effectiveness of replacing the DT vaccine with the DTaP vaccine is affected by the level of pertussis morbidity, with the ICER becoming more favorable in the high-morbidity case. The indirect effect has little impact on the ICER. Thus, policy-makers should continue to monitor the pertussis epidemic in the post-COVID-19 era, and determine the need to introduce a booster based on perceived trends.

Prévention de la coqueluche chez le nouveau-né : faut-il vacciner les femmes enceintes à chaque grossesse ?

Pertussis is a respiratory disease that can be fatal at all ages but especially in infants before their mandatory vaccination. Recent epidemiological data shows a decrease in the number of pertussis cases, but a resurgence cannot be excluded in the coming years due to the cyclic evolution of the disease and the loosening of hygiene measures. Two approaches are used to protect infants before their vaccination: vaccination of the mother during pregnancy and vaccination of all the infant's close relatives (cocooning). The vaccination of the mother during pregnancy is more effective. The uncertain risk of chorioamniotitis associated with vaccination during pregnancy is insufficient to question this strategy.

Immunization with autotransporter Vag8 prevents coughing induced by Bordetella pertussis infection in mice.

Bordetella pertussis causes pertussis, which is characterized by paroxysmal coughing. This disease is generally prevented through vaccination; however, the number of pertussis cases is increasing worldwide despite high vaccination coverage. We previously reported that an autotransporter of B. pertussis, virulence-associated gene 8 (Vag8), causes coughing in combination with pertussis toxin and lipooligosaccharide. Here, we show that immunization with Vag8 protected mice from coughing after B. pertussis infection and enhanced the efficacy of a current pertussis vaccine containing pertussis toxoid against the cough. Our findings indicate that Vag8 could be a vaccine antigen to prevent pertussis cough.

Pertussis in Poland in 2020.

The epidemiological situation of infectious diseases in Poland in 2020, including pertussis cases, was significantly influenced by the limitation of interpersonal contacts introduced to reduce the transmission of SARS-CoV-2 virus. There was a reduction by more than half in the number of recorded pertussis cases, from 1,629 in 2019 to 753 in 2020. Pertussis is most dangerous for young children, however, it can get sick at any age, and the disease does not leave permanent immunity. Severe pertussis can also develop in the elderly, which may increase the risk of mortality. Adults usually have pertussis is mildly symptomatic and constitute an important reservoir of B. pertussis. The most effective strategy for the prevention of pertussis is still immunization of children in accordance with the Protective Vaccination Program, and in the case of adults, vaccination with the pertussis component in acellular form, repeated regularly every 10 years. The aim of the study was to assess the epidemiological situation of pertussis in Poland in 2020 compared to the situation in previous years, with particular emphasis on the assessment of the vaccination status of children against pertussis. The assessment of the epidemiological situation of pertussis in Poland was performed on the basis of the results of the analysis of unit reports of pertussis registered in the NIPH NIH - NRI in the EpiBaza system and data from the annual bulletin "Infectious diseases and poisonings in Poland in 2020" and the bulletin "Vaccinations in Poland in 2020". In 2020, 753 cases of pertussis were registered. The incidence was 1.96 per 100,000 population and was lower compared to the incidence in 2019 (4.24). The highest incidence of pertussis occurred in the age group 0-4 years (9.9), and high in children and adolescents aged 5-9 years (5.1) and 10-14 years (6.0 per 100,000 population). About half of the cases concerned people over 15 years of age. In general, a higher incidence of women was observed than that of men, as well as a greater number of cases in cities than in rural areas. In 2020, among people suffering from pertussis, 206 people (i.e. 27%) required hospitalization. In 2020, one fatal case of the disease was reported to the epidemiological surveillance system. In Poland, in 2020, there was a decrease in the number of pertussis casesby more than a half compared to the previous year. Despite the decline in disease rates, pertussis remains a publichealth problem as immunization-induced immunity is not sustained throughout life. Increasing the number ofpeople susceptible to pertussis may lead to compensatory epidemics in the future, therefore the highest possiblelevel of vaccination of the population, >92-94%, should be maintained to prevent new cases of pertussis.

Epidemiological profile of pertussis in Brazil from 2010 to 2019: a systematic review

Pertussis is a respiratory infection that severely affects humans, caused by bacteria of the genus Bordetella, especially the species B. pertussis and B. parapertussis, presenting an important cause of infant morbidity and mortality. This disease has received little attention from government authorities over the years, which can cause the disease to re-emerge in the future. This study aimed to carry out a systematic literature review on the epidemiology of pertussis in Brazil between the years 2010 to 2019. The study was carried out based on information collected in national (BVS, ANVISA, DATASUS) and international databases (PubMed, SciELO, CDC). When performing the statistical analysis of confirmed cases by region, there was a significant change in 2014 compared to other years in the Northeast region. While in the Southeast region, in 2013 there was a significant increase compared to 2012 and only reduced in 2015. In the South region, the increase in the number of cases occured sharply in 2012 and only decreased in 2017. In the Center-West region, 2014 was the only year that showes considerable statistical variety. Regarding the age group, children under 1 year old and between 10 and 14 years old are the ones with the highest number of pertussis cases. Regarding gender, no significant changes were detected. Health surveillance, compulsory notification of cases added to social participation are essential, so this disease can be eradicated from Brazil and the world.

Multivariate Tail Probabilities: Predicting Regional Pertussis Cases in Washington State.

In disease modeling, a key statistical problem is the estimation of lower and upper tail probabilities of health events from given data sets of small size and limited range. Assuming such constraints, we describe a computational framework for the systematic fusion of observations from multiple sources to compute tail probabilities that could not be obtained otherwise due to a lack of lower or upper tail data. The estimation of multivariate lower and upper tail probabilities from a given small reference data set that lacks complete information about such tail data is addressed in terms of pertussis case count data. Fusion of data from multiple sources in conjunction with the density ratio model is used to give probability estimates that are non-obtainable from the empirical distribution. Based on a density ratio model with variable tilts, we first present a univariate fit and, subsequently, improve it with a multivariate extension. In the multivariate analysis, we selected the best model in terms of the Akaike Information Criterion (AIC). Regional prediction, in Washington state, of the number of pertussis cases is approached by providing joint probabilities using fused data from several relatively small samples following the selected density ratio model. The model is validated by a graphical goodness-of-fit plot comparing the estimated reference distribution obtained from the fused data with that of the empirical distribution obtained from the reference sample only.

Retrospective analysis of bacterial culture-confirmed pertussis cases in Beijing Children’s hospital from 2014 to 2019 reveals prevention and control of the grim situation in mainland China

ABSTRACT Background Our study aims to explore the epidemiological features of children with bacterial culture-confirmed pertussis visiting Beijing Children’s Hospital, China. Methods From 2014 through 2019, patients with suspected pertussis coming from mainland China provided nasopharyngeal swabs and bacterial culture that was subsequently cultivated. Results During the study period, 6956 children with suspected pertussis from 30 different administrative provinces of mainland China were investigated, of which 1494 cases (21.5%) had positive B. pertussis culture. The number of pertussis cases increased year-on-year, from 122 in 2014 to 279 in 2019. Of the confirmed cases, 38.2% and 26.8% were identified in the summer and autumn, respectively. The age distribution of children with pertussis showed that 77.2% were <12 months old, including 56.0% <6 months old. Only thirteen B. parapertussis isolates and one B. bronchiseptica isolates were collected in the present samples. Conclusions The present culture-confirmed cases reveal the severe epidemic situation of pertussis spreading over the whole country and mainly affecting the infants. It is necessary to set up hospital-based surveillance with reliable laboratory methods to promote clinical awareness and to monitor the disease.

Effectiveness of four doses of pertussis vaccine during infancy diminished in elementary school age: A test-negative case-control study in Japan

ObjectiveThe Japanese national immunization program recommends that children receive 4 doses of acellular pertussis vaccine between 3 months and 2 years of age. Nevertheless, the number of pertussis cases is increasing in elementary school children aged 6–12 years. Therefore, a test-negative case-control study was conducted to assess the effectiveness of the pertussis vaccine program. MethodsSubjects included children aged ≥3 months who visited a collaborating hospital due to pertussis-specific cough between October 2017 and November 2019. All subjects underwent diagnostic tests for pertussis, and those diagnosed as positive were regarded as cases. Subjects diagnosed as pertussis-negative were classified as controls. Vaccination history was collected using a questionnaire administered to parents with reference to immunization records. Logistic regression models were employed to calculate the odds ratio (OR) and 95% confidence interval for laboratory-confirmed pertussis. ResultsOf 187 recruited subjects (120 cases and 67 controls), questionnaire responses were obtained for 145 subjects (95 cases and 50 controls). Compared with unvaccinated subjects, the vaccine effectiveness (VE) of 4 doses was 70% among all subjects and reached to 90% with marginal significance among subjects under 6 years of age. However, among school-aged subjects, the VE was not suggestive of protection against pertussis (VE: 8%). For vaccinees given 4 doses, the OR for developing pertussis increased significantly with longer duration since the fourth dose (compared with <4.5 years, OR of 6.0–8.2 years = 5.74; OR of ≥8.3 years = 3.88; P for trend by duration < 0.01). ConclusionEffectiveness of administering 4 doses of pertussis vaccine during infancy decreases with time passed since the fourth dose. This regimen does not protect school-aged children against pertussis.

The epidemic of erythromycin-resistant Bordetella pertussis with limited genome variation associated with pertussis resurgence in China

ABSTRACT Background The resurgence of Bordetella pertussis infections leading to whooping cough is a concern in many parts of the world. The number of pertussis cases in China has increased significantly since 2013. Research design and methods In this study, whole-genome sequencing analysis was performed for 388 B. pertussis strains isolated in China from the 1970s to 2018, combining 594 published strains from around the world. Results This study revealed that lineage V diverged about 50 years ago in China, while lineage IV is dominant in the other countries. It also revealed that the erythromycin-resistant sub-lineages Va, Vb, and Vc with limited genomic variation emerged 11 ~ 12 years ago. These three sub-lineages were identified after the co-purified acellular vaccines (cp-ACVs) completely replaced the previous whole cell vaccines (WCVs) after the national immunization program of 2012. It suggests that the cp-ACVs cannot induce immunity that is potent enough to restrict the spread of the lineage V, antibiotic abuse further favors the spread of this lineage in China. Conclusions These findings demand a reassessment of the immunization strategy and development of new vaccines in China to stop the resurgence and drug resistance of B. pertussis.

The long-term effects of meteorological parameters on pertussis infections in Chongqing, China, 2004\u20132018

Evidence on the long-term influence of climatic variables on pertussis is limited. This study aims to explore the long-term quantitative relationship between weather variability and pertussis. Data on the monthly number of pertussis cases and weather parameters in Chongqing in the period of 2004–2018 were collected. Then, we used a negative binomial multivariable regression model and cointegration testing to examine the association of variations in monthly meteorological parameters and pertussis. Descriptive statistics exhibited that the pertussis incidence rose from 0.251 per 100,000 people in 2004 to 3.661 per 100,000 persons in 2018, and pertussis was a seasonal illness, peaked in spring and summer. The results from the regression model that allowed for the long-term trends, seasonality, autoregression, and delayed effects after correcting for overdispersion showed that a 1 hPa increment in the delayed one-month air pressure contributed to a 3.559% (95% CI 0.746–6.293%) reduction in the monthly number of pertussis cases; a 10 mm increment in the monthly aggregate precipitation, a 1 °C increment in the monthly average temperature, and a 1 m/s increment in the monthly average wind velocity resulted in 3.641% (95% CI 0.960–6.330%), 19.496% (95% CI 2.368–39.490%), and 3.812 (95% CI 1.243–11.690)-fold increases in the monthly number of pertussis cases, respectively. The roles of the mentioned weather parameters in the transmission of pertussis were also evidenced by a sensitivity analysis. The cointegration testing suggested a significant value among variables. Climatic factors, particularly monthly temperature, precipitation, air pressure, and wind velocity, play a role in the transmission of pertussis. This finding will be of great help in understanding the epidemic trends of pertussis in the future, and weather variability should be taken into account in the prevention and control of pertussis.

Clinical and epidemiological features of pertussis in Salvador, Brazil, 2011-2016.

Pertussis, a severe respiratory infection caused by Bordetella pertussis, is distributed globally. Vaccination has been crucial to annual reductions in the number of cases. However, disease reemergence has occurred over the last decade in several countries, including Brazil. Here we describe the clinical and epidemiological aspects of suspected pertussis cases in Salvador, Brazil, and evaluate factors associated with case confirmation. This descriptive and retrospective study was conducted in the five hospitals in Salvador that reported the highest number of pertussis cases between 2011–2016. Demographic and clinical data were recorded for each patient. Bivariate analysis was performed to evaluate differences between groups (confirmed vs. unconfirmed cases) using Pearson’s Chi-square test or Fisher’s exact test. Results: Of 529 suspected pertussis cases, 29.7% (157/529) were confirmed by clinical, clinical-epidemiological or laboratory criteria, with clinical criteria most frequently applied (63.7%; 100/157). Unvaccinated individuals (43.3%; 68/157) were the most affected, followed by age groups 2–3 months (37.6%; 59/157) and <2 months (31.2%; 49/157). Overall, ≤50% of the confirmed cases presented a complete vaccination schedule. All investigated cases presented cough in association with one or more symptoms, especially paroxysmal cough (66.9%; 105/529) (p = 0.001) or cyanosis (66.2%; 104/529) (p<0.001). Our results indicate that pertussis occurred mainly in infants and unvaccinated individuals in Salvador, Brazil. The predominance of clinical criteria used to confirm suspected cases highlights the need for improvement in the laboratory tools used to perform rapid diagnosis. Fluctuations in infection prevalence demonstrate the importance of vaccination strategies in improving the control and prevention of pertussis.

Epidemiology of pertussis in Tunisia; results of five years 2013-2017

Abstract Background Pertussis or whooping cough, is a highly contagious respiratory disease caused by a bacteria gram negative mainly Bordetella pertussis. It is globally endemic despite a high vaccination coverage. In 2014, the World Health Organization estimated the total number of affected persons to 16 million and the number of child deaths reached 190 000. Since 2012, many countries have experienced a resurgence of pertussis including Tunisia. Our objective was to describe the epidemiological situation of pertussis in Tunisia from 2013 to 2017. Methods Our study was a retrospective descriptive study based on data of the surveillance system of Mandatory Reporting Diseases in Tunisia from 2013 to 2017. Data were collected using the declaration standardized forms which included in addition to the socio-demographic data, information regarding vaccination status, date of onset of symptoms and laboratory results (culture and PCR). Data entry was using EpiData and data analysis using SPSS-20. Results During the study period, a total of 252 cases were notified. Males were more affected (55.1%). Age was in average 89 days (3 months). Almost the third were hospitalized in Intensive Care Unit (32.2%). Most cases were reported during 2013 and 2014 (35.7% et 55.5% respectively) and the lethality rate reached 7.2% in 2014. Half cases were notified in the Grand Tunis region. PCR was positive in 74.1% of the cases and bacterial culture was positive in 14.3%, isolating Bortedella pertussis. Vaccination status was mentioned in 70.5% of the cases: it was up-to-date in only 35.7% of the cases and incomplete in 9.8% of the cases. Conclusions Our results showed that pertussis has known a considerable increase the last years, especially in 2013 and 2014. This prompts us to be more vigilant regarding this disease, which has been neglected the last decades. Education of population as well as health professionals is extremely important, particularly the importance of vaccination and preventive measures. Key messages From 2013 to 2017, number of pertussis cases in Tunisia varied with a considerable increase in 2013 and 2014. With the increase of pertussis cases and severity, preventive measures should be taken especially the importance of vaccination.

Neonatal Pertussis, an Under-Recognized Health Burden and Rationale for Maternal Immunization: A Systematic Review of South and South-East Asian Countries.

Pertussis is an under-recognized cause of neonatal morbidity and mortality. To review information on the epidemiology and disease burden of neonatal pertussis in South and Southeast Asian countries, a systematic literature review of three bibliographic databases was undertaken. Peer-reviewed original studies on neonatal pertussis epidemiology and burden published since 2000, with a geographical scope limited to South and Southeast Asian countries, were included. Data were systematically extracted based on parameters defined a priori. Our findings show that the burden of neonatal pertussis and its complications is substantial. An increase in the number of pertussis cases has been noted since early 2000, ranging from 61 to 92.9% in infants 0–3 months old. The most common symptoms an infant is likely to present with are cough with or without paroxysms, cyanosis, apnea, tachypnea, difficulty in breathing and leukocytosis. In addition, it can lead to hospitalization (length of stay: 5–7 days), complications (e.g., pneumonia, seizures) and mortality ranging from 5.6 to 14.7%. Other observations indicate that diagnosis is challenging because of non-specific clinical symptoms. Specifically, for obstetricians and gynecologists, the information available for making informed decisions on the prevention of neonatal pertussis is unreliable. Maternal immunization against pertussis during late stages of pregnancy has proven to be efficacious and well tolerated. A high burden of neonatal pertussis, as well as its complications, is observed in South and Southeast Asian countries. There is a need to intensify efforts to protect this vulnerable population with maternal vaccination.Funding: GlaxoSmithKline Biologicals SAPlain Language Summary: Plain language summary available for this article. Please see Fig. 1 and the following link: https://doi.org/10.6084/m9.figshare.7951187.

Monitoring public interest toward pertussis outbreaks: an extensive Google Trends–based analysis

Pertussis is a vaccine-preventable disease. Despite this, it remains a major health problem among children in developing countries and in recent years, has re-emerged and has led to considerable outbreaks. Pertussis surveillance is of paramount importance; however, classical monitoring approaches are plagued by some shortcomings, such as considerable time delay and potential underestimation/underreporting of cases. This study aims at investigating the possibility of using Google Trends (GT) as an instrument for tracking pertussis outbreaks to see if infodemiology and infoveillance approaches could overcome the previously mentioned issues because they are based on real-time monitoring and tracking of web-related activities. In the present study, GT was mined from inception (01 January 2004) to 31 December 2015 in the different European countries. Pertussis was searched using the 'search topic' strategy. Pertussis-related GT figures were correlated with the number of pertussis cases and deaths retrieved from the European Centre for Disease prevention and Control database. At the European countries level, correlation between pertussis cases and GT-based search volumes was very large (ranging from 0.94 to 0.97) from 2004 to 2015. When examining each country, however, only a few reached the threshold of statistical significance. GT could be particularly useful in pertussis surveillance and control, provided that the algorithm is better adjusted and refined at the country level.

Genetic Variation of Bordetella pertussis in Austria.

In Austria, vaccination coverage against Bordetella pertussis infections during infancy is estimated at around 90%. Within the last years, however, the number of pertussis cases has increased steadily, not only in children but also in adolescents and adults, indicating both insufficient herd immunity and vaccine coverage. Waning immunity in the host and/or adaptation of the bacterium to the immunised hosts could contribute to the observed re-emergence of pertussis. In this study we therefore addressed the genetic variability in B. pertussis strains from several Austrian cities. Between the years 2002 and 2008, 110 samples were collected from Vienna (n = 32), Linz (n = 63) and Graz (n = 15) by nasopharyngeal swabs. DNA was extracted from the swabs, and bacterial sequence polymorphisms were examined by MLVA (multiple-locus variable number of tandem repeat analysis) (n = 77), by PCR amplification and conventional Sanger sequencing of the polymorphic regions of the prn (pertactin) gene (n = 110), and by amplification refractory mutation system quantitative PCR (ARMS-qPCR) (n = 110) to directly address polymorphisms in the genes encoding two pertussis toxin subunits (ptxA and ptxB), a fimbrial adhesin (fimD), tracheal colonisation factor (tcfA), and the virulence sensor protein (bvgS). Finally, the ptxP promoter region was screened by ARMS-qPCR for the presence of the ptxP3 allele, which has been associated with elevated production of pertussis toxin. The MLVA analysis revealed the highest level of polymorphisms with an absence of MLVA Type 29, which is found outside Austria. Only Prn subtypes Prn1/7, Prn2 and Prn3 were found with a predominance of the non-vaccine type Prn2. The analysis of the ptxA, ptxB, fimD, tcfA and bvgS polymorphisms showed a genotype mixed between the vaccine strain Tohama I and a clinical isolate from 2006 (L517). The major part of the samples (93%) displayed the ptxP3 allele. The consequences for the vaccination strategy are discussed.

Complete genome sequence of a clinical Bordetella pertussis isolate from Brazil.

There has been a resurgence in the number of pertussis cases in Brazil and around the world. Here, the genome of a clinical Bordetella pertussis strain (Bz181) that was recently isolated in Brazil is reported. Analysis of the virulence-associated genes defining the pre- and post-vaccination lineages revealed the presence of the prn2-ptxS1A-fim3B-ptxP3 allelic profile in Bz181, which is characteristic of the current pandemic lineage. A putative metallo-β-lactamase gene presenting all of the conserved zinc-binding motifs that characterise the catalytic site was identified, in addition to a multidrug efflux pump of the RND family that could confer resistance to erythromycin, which is the antibiotic of choice for treating pertussis disease.

An outbreak of pertussis in rural Texas: an example of the resurgence of the disease in the United States.

During 2012, an increase in the number of pertussis cases or outbreaks was reported among most states within the United States. The majority of these cases included previously vaccinated children between the ages of 7-10 years. This underscores the growing concern regarding current immunization practices and vaccine efficacy, especially as it pertains to pertussis prevention within this age group. In the fall of 2012, an outbreak of pertussis occurred within a school district in a rural Texas county that was reflective of this national pattern. Our objective is to describe this outbreak, highlight the similarities with the national trend, and identify strategies for better disease prevention. The cases in this outbreak were interviewed and laboratory testing done. Information regarding exposure and immunization history among cases was obtained. Immunization audits of the affected institutions were also conducted. We performed a descriptive analysis of the collected data using EPI-INFO software v.3.5.3. A total of 34 cases were identified in this outbreak, of which 23 were PCR confirmed and 11 were epidemiologically linked. Ages ranged from 5 months to 12 years, and 62 % were among children aged 7-10 years. All cases were up-to-date on their pertussis vaccinations. Immunization coverage rate was over 90 % within each of the affected institutions. The characteristics of this outbreak bear striking similarities to the current national trend in terms of age groups and immunization status of the affected cases. Increased focus on this vulnerable target group, including heightened scrutiny of vaccine efficacy and delivery, is indicated.

Seroepidemiology of Pertussis in 10-15 Years Old Healthy Children in Isparta Province, Turkey

Pertussis, a highly contagious respiratory disease, commonly affects infants and young children and can be fatal, especially in babies less than one year of age. Bordetella pertussis continues to circulate even in populations where a high vaccine coverage of infants and children is achieved. Adults are reservoirs for infections in infants, in whom pertussis may be severe and life-threatening. Despite the rising rates of vaccination in our country and all over the world for the past 25 years, the number of pertussis cases among adolescents and adults has been increasing. To decrease the risk of pertussis infection and thus protect adults and adolescents against pertussis, booster doses should be administered to preschool children and adolescents. In order to decide when to administer the booster doses in a country, age-specific seropidemiology of the disease should be known. The aim of this study was to determine the pertussis toxin antibody levels of fully vaccinated healthy children in Isparta, Turkey, aged 10-15 years old. A total of 296 participants, that comprised fully vaccinated 254 healthy elementary-school students aged between 10-15 years (126 male, 128 female) and 42 adults between 18-39 years old (21 male, 21 female) were included in the study with informed consent. The sensitivities of subjects to pertussis were tested by the determination of pertussis toxin IgG levels with the use of commercial ELISA test (Genzyme Virotech, Germany). In our study, the seropositivity rate was found 12.6% (32/254) for 10-15 age group, however all the adult subjects were seronegative. Thus the total seropositivity rate was estimated as 10.8% (32/296). Pertussis toxin IgG seropositivity rate was 12.7% (16/126) for males and 12.5% (16/128) for females, and there was no significant gender difference (p> 0.05). The highest seropositivity rates were detected at 10(th) (23.8%) and 11(th) (19%) years in males, and 12(th) and 14(th) (23.8%) years in females. No seropositivity was detected in individuals over age 15 in our study. Since adults lose their immune protection gained by pertussis vaccination, they start becoming an infection source for infants. Therefore, a booster dose of acellular pertussis vaccine should be considered in preschool period and at ages 14-18. Further studies regarding diagnosis and surveillance of pertussis disease are required, as well as enhancement of vaccination rates.

Evaluation of serological tests for diagnosis of Bordetella pertussis infection in adolescents and adults

Bacterial agglutination antibodies against Bordetella pertussis, Yamaguchi and Tohama strains, are frequently measured for serodiagnosis of pertussis infection in Japan. To determine the serological criteria, the comparative titres of bacterial agglutination antibody and anti-pertussis toxin (PT) antibody were evaluated. Antibody titres were analysed in 36 definitive (fourfold increase in agglutination antibody) and 137 presumptive (high titre of single-antibody) cases of B. pertussis infection among adolescents and adults, and in a control group of 318 healthy volunteers. When a single Yamaguchi agglutinin titre of ≥ 1:1280 (> three SD above the geometric mean for the control group) was taken as diagnostic, the sensitivity and specificity at 4-5 weeks after onset of cough were 58% and 98%, respectively. Using this criterion, the clinical findings in presumptive cases were almost identical to those in definitive cases. When the two tests were compared using 318 control sera, there was no association between the Tohama agglutinin titre and the anti-PT antibody titre, whereas a weak association between the Yamaguchi agglutinin titre and the anti-PT antibody titre was observed. When the numbers of pertussis cases with high antibody titres in the two tests were compared, 60% of cases with a Yamaguchi agglutinin titre of ≥1:1280 showed an anti-PT antibody titre of ≥100 EU/mL. These results indicate that the bacterial agglutination test is a method with low sensitivity and specificity for the diagnosis of B. pertussis infection. Therefore, to yield an accurate diagnosis, anti-PT antibody levels should be measured instead of bacterial agglutination antibody.