Review of bioaerosols from different sources and their health impacts

The emission of bioaerosols in the ambient atmosphere from different sources is a cause of concern for human health and the environment. Bioaerosols are a combination of biotic matter like microbes and pollens. The present review emphasizes the understanding of various sources of bioaerosols (industries, municipal solid waste, and medical facilities), their components, and their impact on human health. The study of bioaerosols is of great importance as large numbers of people are estimated to be exposed on the global scale. Bioaerosols exposure in different work environments results in health issues such as infectious diseases, allergies, toxic effects, and respiratory problems. Hence, extensive research is urged to establish an effective assessment of bioaerosols exposure in the workplace, risks involved, distribution, and validation. The present review is intended to explore the relationship between bioaerosols exposure to the atmosphere and its impacts on human health. Some of the preliminary findings, based on our analysis of bioaerosols arising from municipal solid waste at a landfill site and a waste transfer station in Hyderabad, India, are also discussed herein.

[Respiratory infections: Additional transmission-based precautions in healthcare facilities]

INTRODUCTION

In health care, measures against cross-transmission of microorganisms are codified by standard precautions, and if necessary, they are supplemented by additional precautions.

STATE OF THE ART

Several factors impact transmission of microorganisms via the respiratory route: size and quantity of the emitted particles, environmental conditions, nature and pathogenicity of the microorganisms, and degree of host receptivity. While some microorganisms necessitate additional airborne or droplet precautions, others do not.

PROSPECTS

For most microorganisms, transmission patterns are well-understood and transmission-based precautions are well-established. For others, measures to prevent cross-transmission in healthcare facilities remain under discussion.

CONCLUSIONS

Standard precautions are essential to the prevention of microorganism transmission. Understanding of the modalities of microorganism transmission is essential to implementation of additional transmission-based precautions, particularly in view of opting for appropriate respiratory protection.

Severe pertussis disease in a paediatric population: The role of age, vaccination status and prematurity

AIM

To estimate hospitalisation rate and investigate the role of age, prematurity and vaccination status in severe pertussis cases.

METHODS

We retrospectively evaluated 200 children aged 0-14 years, admitted to the emergency rooms of Meyer Hospital of Florence and Pisa Hospital with a diagnosis of pertussis from 1 October 2010 to 31 January 2020.

RESULTS

Children younger than 12 months were 63.0%. Preterm infants were 6.5%. The rate of hospitalisation was 49.0%. Among hospitalised cases, 80.6% were younger than 5 months. Overall, 62.0% were unvaccinated; this percentage increased among hospitalised (73.5%) and preterm subsamples (76.9%). Delays in pertussis vaccination were found in 57.7% of term infants and in 80.0% of preterms. Multivariable analysis confirmed the age under 2 months as the variable at higher risk for hospitalisation (OR 4.49, 95% CI 1.85-10.96, p < 0.001). Being fully vaccinated represented a significant protective factor (OR 0.12, 95% CI 0.04-0.35, p < 0.001).

CONCLUSION

Older classes of age and a complete vaccination, in time with the recommended schedule, are both protective factors for hospitalisation in severe pertussis disease. The widespread vaccination delay frequently observed in preterm children may be the cause for their higher rate of hospitalisation.

Donnan Potential across the Outer Membrane of Gram-Negative Bacteria and Its Effect on the Permeability of Antibiotics

The cell envelope structure of Gram-negative bacteria is unique, composed of two lipid bilayer membranes and an aqueous periplasmic space sandwiched in between. The outer membrane constitutes an extra barrier to limit the exchange of molecules between the cells and the exterior environment. Donnan potential is a membrane potential across the outer membrane, resulted from the selective permeability of the membrane, which plays a pivotal role in the permeability of many antibiotics. In this review, we discussed factors that affect the intensity of the Donnan potential, including the osmotic strength and pH of the external media, the osmoregulated periplasmic glucans trapped in the periplasmic space, and the displacement of cell surface charges. The focus of our discussion is the impact of Donnan potential on the cellular permeability of selected antibiotics including fluoroquinolones, tetracyclines, β-lactams, and trimethoprim.

Asymptomatic Bordetella pertussis infections in a longitudinal cohort of young African infants and their mothers

Recent pertussis resurgence in numerous countries may be driven by asymptomatic infections. Most pertussis surveillance studies are cross-sectional and cannot distinguish asymptomatic from pre-symptomatic infections. Longitudinal surveillance could overcome this barrier, providing more information about the true burden of pertussis at the population level. Here we analyze 17,442 nasopharyngeal samples from a longitudinal cohort of 1320 Zambian mother/infant pairs. Our analysis has two elements. First, we demonstrate that the full range of IS481 qPCR CT values provides insight into pertussis epidemiology, showing concordance of low and high CT results over time, within mother/infant pairs, and in relation to symptomatology. Second, we exploit these full-range qPCR data to demonstrate a high incidence of asymptomatic pertussis, including among infants. Our results demonstrate a wider burden of pertussis infection than we anticipated in this population, and expose key limitations of threshold-based interpretation of qPCR results in infectious disease surveillance.

Asymptomatic Bordetella pertussis infections in young African infants and their mothers identified within a longitudinal cohort

Despite long-standing vaccination programs, pertussis incidence has increased in numerous countries; transmission by asymptomatic individuals is a suspected driver of this resurgence. However, unequivocal evidence documenting asymptomatic infections in adults and children is lacking due, in part, to the cross-sectional nature of most pertussis surveillance studies. In addition, modern pertussis surveillance relies on quantitative PCR (qPCR) using fixed diagnostic thresholds to identify cases. To address this gap, we present a longitudinal analysis of 17,442 nasopharyngeal samples collected from a cohort of 1,320 Zambian mother/infant pairs. Using full-range cycle threshold (CT) values from IS481 qPCR assays, we document widespread asymptomatic infections among mothers and also, surprisingly, among young infants. From an initial group of eight symptomatic infants who tested positive by qPCR, we identify frequent contemporaneous subclinical infections in mothers. Within the full cohort, we observe strong temporal correlation between low- and high-intensity qPCR signals. We compute a single time-averaged score for each individual summarizing the evidence for pertussis infection (EFI), and show that EFI strongly clusters within mother/infant pairs, and is strongly associated with clinical symptomatology and antibiotic use. Overall, the burden of pertussis here is substantially underestimated when restricting diagnostic criteria to IS481 CT≤35. Rather, we find that full-range CT values provide valuable insights into pertussis epidemiology in this population, and illuminate the infection arc within individuals. These findings have significant implications for quantifying asymptomatic pertussis prevalence and its contribution to overall transmission. Our results also expose limitations of threshold-based interpretations of qPCR assays in infectious disease surveillance.

Pertussis (Keuchhusten)

Pertussis wird durch das gramnegative Bakterium Bordetella pertussis verursacht. Die Krankheitsmanifestationen reichen von unspezifischem Husten bis zu lebensbedrohlichen Verläufen mit Hyperleukozytose und respiratorischer Insuffizienz, v.a. bei jungen Säuglingen. Die Diagnose basiert auf klinischer Symptomatik und mikrobiologischen Nachweisverfahren. Die Therapie besteht aus Makrolidantibiotika; bei Apnoen kann Koffein versucht werden. Die Inzidenz beträgt 10–40 Fälle/100.000 Bevölkerung und Jahr, bei Säuglingen ist sie am höchsten (ca. 50), gefolgt von Jugendlichen (30–35). Mehr als 50 % der in den ersten 5 Lebensmonaten an Pertussis erkrankten Kinder werden hospitalisiert. Die Impfprävention umfasst Grundimmunisierung und regelmäßige Auffrischimpfungen mit azellulären Impfstoffen. Um schwere Verläufe bei jungen Säuglingen zu verhindern, ist die Impfung schwangerer Frauen am erfolgversprechendsten. Säuglinge geimpfter Mütter sollen zeitgerecht ab dem Alter von 2 Monaten für den Eigenschutz immunisiert werden.

[Pertussis (whooping cough)]

Pertussis wird durch das gramnegative Bakterium Bordetella pertussis verursacht. Die Krankheitsmanifestationen reichen von unspezifischem Husten bis zu lebensbedrohlichen Verläufen mit Hyperleukozytose und respiratorischer Insuffizienz, v.a. bei jungen Säuglingen. Die Diagnose basiert auf klinischer Symptomatik und mikrobiologischen Nachweisverfahren. Die Therapie besteht aus Makrolidantibiotika; bei Apnoen kann Koffein versucht werden. Die Inzidenz beträgt 10–40 Fälle/100.000 Bevölkerung und Jahr, bei Säuglingen ist sie am höchsten (ca. 50), gefolgt von Jugendlichen (30–35). Mehr als 50 % der in den ersten 5 Lebensmonaten an Pertussis erkrankten Kinder werden hospitalisiert. Die Impfprävention umfasst Grundimmunisierung und regelmäßige Auffrischimpfungen mit azellulären Impfstoffen. Um schwere Verläufe bei jungen Säuglingen zu verhindern, ist die Impfung schwangerer Frauen am erfolgversprechendsten. Säuglinge geimpfter Mütter sollen zeitgerecht ab dem Alter von 2 Monaten für den Eigenschutz immunisiert werden.

Comparative Clinical Evaluation of NeoPlex RB-8 with Seeplex PneumoBacter ACE for Simultaneous Detection of Eight Respiratory Bacterial Pathogens

There are several convenient and accurate molecular assays to detect respiratory bacterial infection. The NeoPlex RB-8 detection kit (NeoPlex RB-8) is a new multiplex real-time PCR assay that simultaneously detects Streptococcus pneumoniae, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila, Haemophilus influenzae, Bordetella pertussis, Bordetella parapertussis, and Moraxella catarrhalis in a single test. This study compared the clinical concordance of NeoPlex RB-8 with another method, Seeplex PneumoBacter ACE detection assay (Seeplex PB ACE), which simultaneously detects S. pneumoniae, M. pneumoniae, C. pneumoniae, L. pneumophila, H. influenzae, and B. pertussis We tested 2,137 nasopharyngeal swab and sputum specimens using both assays. For discordant Bordetella parapertussis and M. catarrhalis specimens, we also performed bidirectional sequencing. For S. pneumoniae, M. pneumoniae, C. pneumoniae, L. pneumophila, H. influenzae, and B. pertussis, which are detected by both NeoPlex RB-8 and Seeplex PB ACE, the positive and negative agreement between the two assays ranged from 91.7 to 100% (κ = 0.918 to 1). S. pneumoniae and H. influenzae were the most discordant targets and measured with higher sensitivity and specificity by NeoPlex RB-8 than Seeplex PB ACE. For Bordetella parapertussis and M. catarrhalis, which are not detected by Seeplex PB ACE, NeoPlex RB-8 sensitivity and specificity were >99%. Overall, NeoPlex RB-8 was highly comparable to Seeplex PB ACE, but NeoPlex RB-8 was more clinically accurate, with higher throughput and more convenience.

Recommendations to control pertussis prioritized relative to economies: A Global Pertussis Initiative update

Pertussis is a vaccine-preventable disease that causes morbidity and mortality, particularly in infants and children <5 years of age. The Global Pertussis Initiative (GPI) recommendations represent a systematic evaluation and prioritization of strategies to prevent pertussis-related infant and child deaths, reduce global disease burden and prevent resurgence through vaccination strategies and public health policies at national, regional and local levels. The GPI recommendations are based on clinical trials and observational and surveillance data, which are essential in the planning, implementation and evaluation of vaccination practices and best use of available resources. Many low- and middle-income countries (LMIC) continue to use whole-cell pertussis (wP) vaccines for primary vaccination, while most high-income countries have replaced wP with the less-reactogenic acellular pertussis (aP) vaccines. This present manuscript pertains to discussions held during the GPI's meeting on November 11-13, 2016, in Cape Town, Republic of South Africa. The GPI recommends that LMIC aim for high coverage of infant series pertussis vaccines as a priority. In LMIC and countries with constrained vaccine funding, if wP vaccines are currently used, wP should continue to be used. Furthermore, given that protection against disease and death due to pertussis in neonates is a key priority of the GPI, it recommends that ap immunization in pregnancy should be implemented as a priority in all countries if resources allow. Given that surveillance and epidemiology data on which to base vaccine decisions are important, the GPI also suggests that, in areas where wP vaccines are implemented, standardization and calibration of wP vaccines are checked, considering the many different manufacturers and variable standards of production and quality control. In addition, as immunity to pertussis wanes following the primary infant series of vaccination, the GPI further recommends that toddlers, adolescents, healthcare and childcare workers receive booster vaccine doses, where resources allow.

Apnea in infants hospitalized with pertussis: Incidence and gestational smoking association

BACKGROUND

Apnea is a life-threatening complication of pertussis, now a re-emerging cause of infant hospitalization worldwide. The incidence of apnea during pertussis ranges widely. The aim of this study was therefore to determine the incidence of apnea in hospitalized infants diagnosed with pertussis and to identify relevant risk factors for apnea.

METHODS

This was a retrospective analytical study. We included children hospitalized with pertussis at a tertiary hospital during a 5 year period from 2010 to 2015. Nasopharyngeal aspirates (NPA) were obtained in all subjects. Real-time polymerase chain reaction was used to test NPA samples for Bordetella pertussis. The daily charts were assessed to identify inpatients with apnea. Multivariable logistic regression was performed to identify independent risk factors for inpatient apnea.

RESULTS

Inpatient apnea was identified in 51 of 147 infants with pertussis confirmation (34.7%: 95%CI: 27-42%). Maternal smoking during pregnancy was the only statistically significant, independent predictor of inpatient apnea (OR: 4.48; 95%CI: 1.35-14.8). No statistically significant association was found with gender, corrected age; birthweight, caregiver smoking; lactation, weight at admission <3rd percentile, or hematological parameters.

CONCLUSIONS

The incidence of pertussis apnea was nearly one in three hospitalized infants, and was fourfold more frequent in infants whose mothers smoked during pregnancy.

A review on recent progress in observations, and health effects of bioaerosols

Bioaerosol is a particulate mixture of solid and semi-solid matter combined with biotic matter like pollens, microbes and their fragments. The present review stresses on a cumulative understanding of sources, components, quantification and distribution of bioaerosols with respect to size, and its significant impacts on human health. The present review will be instrumental in devising strategies to understand and manage bioaerosols and reducing their human exposure and associated health hazards. The present review aims explore the relationship between particle and associated biological agents responsible for behaviours like dispersal, total potential health hazards and toxicology level during exposure to bioaerosol.

Pertussis epidemiology in Argentina: TRENDS after the introduction of maternal immunisation

Data on the impact of the recently recommended maternal pertussis vaccination are promising, but still insufficient to universalise this approach. We thus compared the epidemiological data prior to the implementation of this vaccination strategy in Argentina (2012) with the figures reported after 2012. During that 2010–2016 period, two outbreaks occurred, one in 2011 and another in 2016. In the former, the incidence was 6.9/100 000 inhabitants and the case-fatality rate 2.6%. Thereafter, a decline in incidence was detected until 2014. During 2015 and 2016 an increase in the incidence transpired, but this rise was fortunately not accompanied by one in the case fatality ratio. Indeed, in 2016 the case fatality ratio was the lowest (0.6%). Moreover, during the 2016 outbreak, the incidence (3.9/100 000 inhabitants) and the case severity detected in the most vulnerable population (infants 0–2 months) were both lower than those in 2011. Consistent with this pattern, in 2016, in the most populated province of Argentina (Buenos Aires), the case percentage with laboratory-positive results indicating a high number of symptoms (59.1% of the total cases) diminished compared with that detected in the 2011 outbreak without maternal immunisation (71.9%). Using the mathematical model of pertussis transmission we previously designed, we assessed the effect of vaccination during pregnancy on infant incidence. From comparisons between the epidemiological data made through calculations, emerged the possibility that vaccinating women during pregnancy would benefit the infants beyond age 2 months, specifically in the 2–12-month cohort.

Pertussis and parapertussis in children and adults with a persistent cough: an observational study

PURPOSE

We aimed to determine the prevalence, symptoms and course of pertussis and parapertussis among patients at any age with a cough of unknown aetiology that had lasted for ≥ 7 days and to assess the diagnostic value of the symptoms included in the World Health Organisations' (WHO) clinical case definition of pertussis.

METHODS

Patients were enrolled between the 23 April 2012 and 31 December 2014 at 25 general practitioner (GP) centres and three paediatric hospitals. Pertussis was confirmed by culture and/or polymerase chain reaction (PCR) and/or quantitative serology. Parapertussis was confirmed by culture and/or PCR.

RESULTS

Altogether, 549 patients were recruited. Of them, 22 (4.0%; 95% CI 2.5-6.0) had pertussis (predominately diagnosed by positive serology 17/22) and 7 (1.3%; 95% CI 0.5-2.6) had parapertussis. Patients with pertussis were more likely to have inspiratory whooping and posttussive emesis than those with a cough of another/unknown aetiology. However, the presence or absence of these two symptoms did not definitively confirm or exclude pertussis. The sensitivity and specificity of the WHO's clinical definition was 0.77 and 0.38, respectively.

CONCLUSIONS

The prevalence of pertussis and parapertussis among patients with a persistent cough of unknown aetiology in Estonia is low. As clinical symptoms alone cannot be used to distinguish pertussis, we recommend that laboratory testing for pertussis is performed in all patients with a persistent cough regardless of age.

Bordetella pertussis

Pertussis is a highly infectious vaccine-preventable cough illness that continues to be a significant source of morbidity and mortality around the world. The majority of human illness is caused by Bordetella pertussis, and some is caused by Bordetella parapertussis. Bordetella is a Gram-negative, pleomorphic, aerobic coccobacillus. In the past several years, even countries with high immunization rates in early childhood have experienced rises in pertussis cases. Reasons for the resurgence of reported pertussis may include molecular changes in the organism and increased awareness and diagnostic capabilities, as well as lessened vaccine efficacy and waning immunity. The most morbidity and mortality with pertussis infection is seen in infants too young to benefit from immunization. Severe infection requiring hospitalization, including in an intensive care setting, is mostly seen in those under 3 months of age. As a result, research and public health actions have been aimed at better understanding and reducing the spread of Bordetella pertussis. Studies comparing the cost benefit of cocooning strategies versus immunization of pregnant women have been favorable towards immunizing pregnant women. This strategy is expected to prevent a larger number of pertussis cases, hospitalizations, and deaths in infants <1 year old while also being cost-effective. Studies have demonstrated that the source of infection in infants usually is a family member. Efforts to immunize children and adults, in particular pregnant women, need to remain strong.

Assessment of antibody level and avidity against Bordetella pertussis in a cohort of Egyptian individuals aged 1-18 years

Pertussis specific antibodies were studied with respect to quality and quantity in a cohort of apparently healthy Egyptian children and adolescents, with their age range between 1 and 18 years, in an attempt to get a close and clear insight into the current humoral immunization status in this specified group and to try find a relation between the antibody levels and their avidities in eradication of this devastating infectious disease. Our results showed that avidity increase was most marked in young school children (6–8 years) where it seemed to reach a plateau in older children and adolescents. Antibody titer was highest in toddlers (1–2 years) and young school children (6–8 years) groups, most probably following vaccination and/or booster doses. Among children aged 1–5 years, 28% had highly avid and 50% had high titer antibodies, whereas in adolescents aged 13–18 years, 70% had highly avid antibodies and only 30% had high titer antibodies. The results clearly demonstrated that while levels of anti-Bordetella pertussis (B. pertussis) antibodies wane with growing age, the avidity seems to increase, to a plateau, irrespective of further antigen exposure in a pattern showing complete independence of avidity on concentration. The present study draws attention to the importance of avidity measurements, together with conventional ELISAs, for evaluating immunity against pertussis. Being based on a limited sample size, it could open doors for larger-scale surveys to be possible indicators for the need and timing of booster vaccination doses among Egyptians.

[Pertussis vaccine. Reemergence of the disease and new vaccination strategies]

Pertussis continues to be a public health problem despite the significant decrease in its incidence due to routine vaccination. Resurgence of the disease in countries that have maintained high vaccination coverage has been observed in recent years. Although vaccination is the most effective preventive control measure, both natural and artificial immunity wane over time, and thus the protection offered by current vaccines is not long-lasting. Furthermore, acellular vaccines are less effective. The implementation of new vaccine strategies is required. Vaccination of pregnant women is the most effective strategy for preventing pertussis in young infants, who are the most vulnerable, and should be recommended together with cocooning, ie vaccination of future household and extra-domiciliary contacts who are the main transmitters of the disease.

Evaluation of 3 analyte-specific reagents for detection of Bordetella pertussis and Bordetella parapertussis in clinical specimens

The performance of 3 analyte-specific reagents (ASRs), Elitech Biosciences, EraGen Biosciences, and Focus Diagnostic, was evaluated for detection of Bordetella pertussis (BP) and Bordetella parapertussis (BPP) in nasopharyngeal swab specimens. A total of 104 frozen, leftover clinical specimens obtained from pediatric patients during 2011-2012 were included in this study. Performance was compared to the Bordetella real-time polymerase chain reaction (PCR) laboratory-developed test (LDT). The positive percent agreement for detection of BP by Elitech was 96% (95% confidence interval [CI]: 85.14-99.30); EraGen and Focus was 98% (95% CI: 87.99-99.89) in comparison to LDT PCR assay. The negative percent agreement of Elitech, EraGen, and Focus in comparison to LDT was 96% (95% CI: 85.14-99.30), 92% (95% CI: 79.89-97.41), and 96% (95% CI: 85.14-99.30), respectively. Limit of detection (LOD) for BP was 0.1 CFU/reaction by both Focus and EraGen and 1.0 CFU/reaction by Elitech. However, LOD for BPP was lower by EraGen (0.1 CFU/reaction) compared to Focus (1.0 CFU/reaction) and Elitech (1.0 CFU/reaction). These results demonstrate that all 3 ASRs tested are comparable and reliable for routine clinical diagnosis of pertussis and parapertussis.

How to fight pertussis?

Universal pertussis vaccination has successfully decreased pertussis mortality and morbidity in childhood. However, despite intensive vaccination of young children, pertussis remains a major public health problem in both developing and industrialized regions. Recent epidemics in California and Australia demonstrated that the agent of the disease is still circulating. They also revealed several aspects that must not be neglected concerning vaccine-preventable diseases. Indeed, pertussis is one of the oldest vaccine-preventable bacterial diseases, so can provide a good illustration of all of the aspects associated with the need for surveillance after the introduction of vaccination. (i) The type of vaccine: two types of pertussis vaccine, whole cell and acellular, inducing different types of immunity are now used around the world. (ii) The vaccine strategy, the vaccine coverage and the duration of vaccine immunity: pertussis epidemics provide evidence that 90% of the infants must be vaccinated, vaccination must be sufficiently early and both vaccine-induced immunity and natural infection-induced immunity to pertussis wane with time indicating that pertussis is not only a pediatric disease. (iii) The agents of the disease, Bordetella pertussis and Bordetella parapertussis: the intensive vaccination of young infants modified the herd immunity, controlled bacteria similar to the vaccine strains but not all, revealing polymorphism of the agents of the disease evidencing the importance of continuing their isolation and their surveillance as well as monitoring their antibiotic resistance. (iv) The diagnosis of the disease: the epidemics showed the importance of specific diagnostic techniques that are easy to use by medical laboratories and the availability of the reagents required. (v) Communication with the public, the health authorities and the health providers: any changes of vaccine type, vaccine strategy, characteristics of the disease, and biological diagnosis must be associated with appropriate communication with the public and training of healthcare workers. Currently, herd immunity needs to be increased by introducing vaccine boosters for adolescents and adults to protect the most vulnerable group: unvaccinated newborns.

Impact of visitors and hospital staff on nosocomial transmission and spread to community

We develop a deterministic meta-population model to qualitatively capture some key features of disease transmission between a community and its healthcare facility. We consider the disease transmission dynamics within a healthcare facility and between the healthcare facility and its community. The focus of this study is to quantify the roles of the healthcare workers at and visitors to this healthcare facility in shaping the transmission dynamics during a disease outbreak. We stratify the total population into the general population in the community and the healthcare workers and visitors in the healthcare facility, to account for nosocomial transmission in the case when an individual in the community may be exposed to an infection due to a visit to the healthcare facility. Equilibrium stability analysis is carried out to inform long-term outcomes of disease dynamics in the coupled community-health care facility system. The basic reproduction number is calculated and its dependence on the waiting time and various disease transmission rates is analyzed. Numerical simulations are performed with pertussis as the disease in question. The results show that waiting time only affects the peak number of infections in the waiting reception area. The results also indicate that transmission rate of infective residents in the community and the transmission rate of the infective visitors at the healthcare facility have decisive impact on disease eradication/persistence of the coupled system; while other modes of transmissions are less important, affecting the peak number of infections at best.

Prospective nationwide surveillance of hospitalizations due to pertussis in children, 2006-2010

BACKGROUND

Frequency of pertussis is highly variable from country to country and it depends on multiple factors including case definitions and type of surveillance systems used. Many countries recently reported an increase of pertussis cases especially in infants and adolescents.

METHODS

From April 2006 to March 2011, 15-year-old patients hospitalized with suspected or proven pertussis were reported to the Swiss Pediatric Surveillance Unit. Patients with ≥14 days of cough plus paroxysms, whooping or post-tussive vomiting fulfilled the clinical case definition of pertussis. For laboratory confirmation, Bordetella pertussis polymerase chain reaction was offered free of charge.

RESULTS

Data were available from 159 of 173 reported cases and 130 (90% of them <12 months old) were eligible including 125 laboratory-confirmed B. pertussis infections. Rates per 100,000 population were 2.6 (<16 years) and 38.8 (<12 months), respectively. Most frequent complications were cyanosis (63%) and sleep disturbance (60%); 35 (27%) patients received intensive care and 1 patient died. Source of infection was known in 79 (61%) patients and was mainly a sibling, parent or both. Most patients were unimmunized (65%) or incompletely immunized (30%).

CONCLUSIONS

The high rate of pertussis hospitalization in young infants established in this surveillance project and the incomplete pertussis immunization status in almost all hospitalized patients require further efforts for improvement. In addition, introduction of pertussis immunizations for all adolescents (in 2013), young adults (in 2012) and pregnant women (in 2013) in Switzerland should increase indirect protection of vulnerable newborns and infants too young to be fully immunized.

Acellular pertussis vaccines protect against disease but fail to prevent infection and transmission in a nonhuman primate model

Pertussis is a highly contagious respiratory illness caused by the bacterial pathogen Bordetella pertussis. Pertussis rates in the United States have been rising and reached a 50-y high of 42,000 cases in 2012. Although pertussis resurgence is not completely understood, we hypothesize that current acellular pertussis (aP) vaccines fail to prevent colonization and transmission. To test our hypothesis, infant baboons were vaccinated at 2, 4, and 6 mo of age with aP or whole-cell pertussis (wP) vaccines and challenged with B. pertussis at 7 mo. Infection was followed by quantifying colonization in nasopharyngeal washes and monitoring leukocytosis and symptoms. Baboons vaccinated with aP were protected from severe pertussis-associated symptoms but not from colonization, did not clear the infection faster than naïve animals, and readily transmitted B. pertussis to unvaccinated contacts. Vaccination with wP induced a more rapid clearance compared with naïve and aP-vaccinated animals. By comparison, previously infected animals were not colonized upon secondary infection. Although all vaccinated and previously infected animals had robust serum antibody responses, we found key differences in T-cell immunity. Previously infected animals and wP-vaccinated animals possess strong B. pertussis-specific T helper 17 (Th17) memory and Th1 memory, whereas aP vaccination induced a Th1/Th2 response instead. The observation that aP, which induces an immune response mismatched to that induced by natural infection, fails to prevent colonization or transmission provides a plausible explanation for the resurgence of pertussis and suggests that optimal control of pertussis will require the development of improved vaccines.

Epidemiology of whooping cough & typing of Bordetella pertussis

Bordetella pertussis is a Gram-negative human-restricted bacterium that evolved from the broad-range mammalian pathogen, Bordetella bronchiseptica. It causes whooping cough or pertussis in humans, which is the most prevalent vaccine-preventable disease worldwide. The introduction of the pertussis whole-cell vaccination for young children, followed by the introduction of the pertussis acellular vaccination (along with booster vaccination) for older age groups, has affected the bacterial population and epidemiology of the disease. B. pertussis is relatively monomorphic worldwide, but nevertheless, different countries are facing different epidemiological evolutions of the disease. Although it is tempting to link vaccine-driven phenotypic and genotypic evolution of the bacterium to epidemiology, many other factors should be considered and surveillance needs to continue, in addition to studies investigating the impact of current clinical isolates on vaccine efficacy.

Using a bayesian latent class model to evaluate the utility of investigating persons with negative polymerase chain reaction results for pertussis

Pertussis remains difficult to control. Imperfect sensitivity of diagnostic tests and lack of specific guidance regarding interpretation of negative test results among patients with compatible symptoms may contribute to its spread. In this study, we examined whether additional pertussis cases could be identified if persons with negative pertussis test results were routinely investigated. We conducted interviews among 250 subjects aged ≤18 years with pertussis polymerase chain reaction (PCR) results reported from 2 reference laboratories in Wisconsin during July-September 2010 to determine whether their illnesses met the Centers for Disease Control and Prevention's clinical case definition (CCD) for pertussis. PCR validity measures were calculated using the CCD as the standard for pertussis disease. Two Bayesian latent class models were used to adjust the validity measures for pertussis detectable by 1) culture alone and 2) culture and/or more sensitive measures such as serology. Among 190 PCR-negative subjects, 54 (28%) had illnesses meeting the CCD. In adjusted analyses, PCR sensitivity and the negative predictive value were 1) 94% and 99% and 2) 43% and 87% in the 2 types of models, respectively. The models suggested that public health follow-up of reported pertussis patients with PCR-negative results leads to the detection of more true pertussis cases than follow-up of PCR-positive persons alone. The results also suggest a need for a more specific pertussis CCD.

Bordetella pertussis infection induces a mucosal IL-17 response and long-lived Th17 and Th1 immune memory cells in nonhuman primates

Despite near universal vaccine coverage, the bacterial pathogen Bordetella pertussis has re-emerged as a major public health concern. We recently developed a baboon (Papio anubis) model of pertussis that provides an excellent model of human pertussis. Using this model, the immune response to pertussis was characterized by measuring cytokines in the nasopharyngeal mucosa of infected baboons. Notably, we observed mucosal expression of interleukin-17 (IL-17) as well as IL-6, IL-23, and several cytokines and chemokines that are orchestrated by IL-17 immune responses. We also found substantial populations of circulating B. pertussis-specific Th17 and Th1 cells in convalescent animals >2 years post-infection consistent with a role in immunological memory to pertussis. Collectively, these data shed important light on the innate and adaptive immune responses to pertussis in a primate infection model and suggest that Th17 and Th1 immune responses contribute to the immunity conferred by natural pertussis infection.

The protective role of maternally derived antibodies against Bordetella pertussis in young infants

In 20 infants with polymerase chain reaction-confirmed pertussis <6 months of age, median cord blood anti-pertussis toxin, anti-filamentous hemagglutinin and anti-pertactin IgG antibody values were lower than in 80 matched controls: 10.5 versus 13.5 anti-pertussis toxin IU/mL, 14.5/18.0 (anti-filamentous hemagglutinin) and 6.0/9.0 (anti-pertactin), respectively. Although differences of median (and mean) antibody values between groups were not significant, they are in line with the concept of infant protection by maternal antibodies and thus support the strategy of pertussis booster immunization in pregnant women.

Critical pertussis in a young infant requiring mechanical ventilation

Pertussis may likely be misdiagnosed in its initial or catarrhal phase as a common respiratory infection. The earlier diagnosis of pertussis really depends on the capability of the medical professional especially in the first line public health services. The lack of awareness in diagnosis of severe pertussis as one of the causes of severe respiratory problems may likely misdiagnose pertussis as respiratory failure or even septic shock. In fact, pertussis may manifest as a critical pertussis which can be fatal due to the respiratory failure that require pediatric intensive care unit using mechanical ventilation. We reported a confirmed pertussis case of a 7-weeks-old female infant referred to our tertiary hospital with gasping leading to respiratory failure and septic shock requiring mechanical ventilation, aggressive fluid therapy, and antibiotics. Pertussis was diagnosed late during the course of illness when the patient was hospitalized. Improvement was noted after administering macrolide which gave a good response. Bordetella pertussis isolation from Bordet-Gengou media culture yielded positive result.

The difficult coughing child: prolonged acute cough in children

Cough is one of the most common symptoms that patients bring to the attention of primary care clinicians. Cough can be designated as acute (<3 weeks in duration), prolonged acute cough (3 to 8 weeks in duration) or chronic (> 8 weeks in duration). The use of the term ‘prolonged acute cough’ in a cough guideline allows a period of natural resolution to occur before further investigations are warranted. The common causes are in children with post viral or pertussis like illnesses causing the cough. Persistent bacterial bronchitis typically occurs when an initial dry acute cough due to a viral infection becomes a prolonged wet cough remaining long after the febrile illness has resolved. This cough responds to a completed course of appropriate antibiotics.

The disease burden of pertussis in adults 50 years old and older in the United States: a retrospective study

Background

While the incidence of pertussis has increased in adolescents and adults in recent years in the U.S., little is known about the incidence and economic burden of pertussis in older adults. This study provides evidence of the incidence of pertussis and direct medical charges associated with pertussis episodes of care (PEOCs) in adults aged 50 years and older in the U.S.

Methods

PEOCs were divided into periods before and after the initial pertussis diagnosis was made (i.e., the index date) to capture any conditions immediately preceding the pertussis diagnosis that may have represented misdiagnoses and subsequent conditions that may have represented sequelae. Data were extracted from IMS's recently acquired SDI databases of longitudinal, patient-level practitioner claims and hospital operational billing records collected from private practitioners and hospitals, respectively, across the U.S. Patients 50 years and older with one or more ICD-9-CM diagnoses for pertussis/whooping cough and/or a laboratory test positive for Bordetella pertussis between 1/1/2006 and 10/31/2010 were eligible for study inclusion. Resource utilization and charges (i.e., unadjudicated claims) associated with the patient's physician and hospital care were analyzed. The nationally projected incidence of pertussis was estimated using a subsample of patients with the required data necessary for projection.

Results

Estimated incidence of diagnosed pertussis ranged from 2.1-4.6 cases per 100,000 people across the two age groups (50–64 and [greater than or equal to] 65) during the years 2006 to 2010. The analysis of charges included 5,748 patients [greater than or equal to] 50 years of age with pertussis. Average charges across the entire episode of care were $1,835 and $14,428 per patient in the outpatient and inpatient settings, respectively. The average number of outpatient (i.e., private practitioner) visits was 2 per patient in both the pre-index and post-index periods.

Conclusions

In the U.S., the incidence of diagnosed pertussis in adults 50 years and older has increased between 2006 and 2010. Healthcare utilization and charges associated with pertussis are substantial, suggesting the need for additional prevention and control strategies and a higher degree of clinical awareness on the part of health care providers. Additional research regarding pertussis in older populations is needed to substantiate these findings.

Differences of IgG antibody avidity after an acellular pertussis (aP) booster in adolescents after a whole cell (wcP) or aP primary vaccination

Compared to whole cell pertussis (wcP) vaccines, acellular pertussis vaccines (aP) have a better safety profile with lower reactogenicity, although their short and long-term efficacy was found to be slightly lower. Up to now, no established serological parameter to predict long-term protection exists. IgG-anti-pertussis avidity possibly determines the effect of different pertussis vaccines and boosting intervals on long-term immunity. Thus, the avidity of a tetanus-diphtheria-aP booster at 10-14 years was tested in three groups of adolescents who had been previously immunized with either five doses of aP (5aP) at 2, 4, 6, 15-18 months and 5-6 years of age, four doses of aP (4aP) or four doses of wcP (4wcP) at 2, 4, 6 and 15-18 months of age. Relative avidity index (RAI) of IgG-anti-pertussis toxin (PT) and IgG-anti-filamentous-hemagglutinin (FHA) was assessed by an adapted ELISA. RAI of IgG-anti-PT and of IgG-anti-FHA correlated positively with antibody concentrations in the pre-vaccination and in the post-vaccination analysis and significantly increased after adolescent booster with aP in all groups. Pre- and post-vaccination, the proportion of participants with IgG-anti-PT RAI>40% (moderate to high avidity) was significantly lower in the 4wcP group (52.9% and 88.9%) compared to the 5aP group (89.5% and 100.0%). In conclusion, TdaP in adolescence induces an increase of antibody avidity and, thus, is able to enhance the binding-quality of antibodies against pertussis. The study suggests including antibody avidity into serological studies on the humoral response to provide information about the long-term efficacy of the vaccine.

Hospitalizations for pertussis in Italy, 1999-2009: analysis of the hospital discharge database

Even if the incidence of pertussis has greatly decreased after the adoption of immunization, it still remains a relevant cause of death in infants in their first years of life. At national level, data are usually greatly underestimated. The objective of this study was to retrospectively review the national hospital discharge form database. The national database was retrospectively searched using the International Classification of Diseases, ninth revision, Clinical Modification system. In the period 1999-2009, 7,768 hospitalizations for pertussis (primary diagnosis) have been registered: 6,971 hospitalizations and 797 day hospital admissions. The annual mean was equal to 633.6 hospitalizations and 72.4 day hospital admissions. The majority of hospitalizations (57.4 %) involved subjects <1 year of age; the mean duration of stay was about 6 days. Conclusion These data, even if restricted to hospitalizations registered at national level, confirm the epidemiological impact of pertussis and its complications in a country with a consistently high vaccination coverage rate.

Prevalence of Bordetella pertussis and Bordetella parapertussis infections in Tunisian hospitalized infants: results of a 4-year prospective study

The prevalence of pertussis in Tunisia remains undetermined essentially because of the unavailability of a basic laboratory diagnostic service. Specific diagnostic tools were applied for the first time in a Tunisian prospective study in order to get a first estimation of the prevalence of Bordetella pertussis/parapertussis infections and to evaluate their use to determine the epidemiologic characteristics of these infections in Tunisian infants. Between 2007 and 2011, a total of 626 samples from 599 infants aged <1 year with and without pertussoid cough were investigated for the presence of B. pertussis/parapertussis using culture and real-time polymerase chain reaction (PCR). The real-time PCR (RT-PCR) targets include IS481 commonly found in B. pertussis, B. bronchiseptica, and B. holmesii; IS1001 specific of B. parapertussis, in combination with the pertussis toxin promoter region gene (ptx) of B. pertussis; and the recA gene specific of B. holmesii. When possible, patients' household contacts provided nasopharyngeal aspirates (NPAs) for RT-PCR detection of B. pertussis/parapertussis or single-serum samples for anti-PT IgG quantification. All except 1 NPAs were negative by conventional culture, whereas PCR gave positive signals for 126 specimens (21%): B. pertussis, B. parapertussis, and Bordetella spp. were detected in 82%, 6%, and 4% of the samples, respectively. The simultaneous presence of B. pertussis and B. parapertussis was noted in 8% of the cases. Pertussis was reported throughout the year with a peak during the summer of the year 2009. The prevalence of Bordetella infection was 20% between 2007 and 2011. Most of these cases corresponded to patients younger than 6 months who received <3 doses of pertussis vaccine. Among the household contacts enrolled in the study, mothers seemed to be the likely source of infection. This study showed that pertussis is still prevalent in Tunisia and that the disease remains a public health problem affecting not only infants but also adults. Given this situation, sensitive and specific laboratory tests are needed to improve the accuracy of pertussis diagnosis.

Nonhuman primate model of pertussis

Pertussis is a highly contagious, acute respiratory illness caused by the bacterial pathogen Bordetella pertussis. Despite nearly universal vaccine coverage, pertussis rates in the United States have been rising steadily over the last 20 years. Our failure to comprehend and counteract this important public health concern is due in large part to gaps in our knowledge of the disease and the mechanisms of vaccine-mediated protection. Important questions about pertussis pathogenesis and mechanisms of vaccine effectiveness remain unanswered due to the lack of an animal model that replicates the full spectrum of human disease. Because current animal models do not meet these needs, we set out to develop a nonhuman primate model of pertussis. We inoculated rhesus macaques and olive baboons with wild-type B. pertussis strains and evaluated animals for clinical disease. We found that only 25% of rhesus macaques developed pertussis. In contrast, 100% of inoculated baboons developed clinical pertussis. A strong anamnestic response was observed when convalescent baboons were infected 6 months following recovery from a primary infection. Our results demonstrate that the baboon provides an excellent model of clinical pertussis that will allow researchers to investigate pertussis pathogenesis and disease progression, evaluate currently licensed vaccines, and develop improved vaccines and therapeutics.

Pertussis: what the pediatric infectious disease specialist should know

Pertussis is a bacterial disease that is transmitted very efficiently from human to human by droplets. It occurs at any age, is endemic in any population, and can cause outbreaks in highly variable frequencies. Hallmark of the disease is cough with or without paroxysms, whoop, and vomiting. Diagnosis relies on clinical suspicion followed by laboratory confirmation (PCR, Serology) and should be followed by prompt antibiotic treatment to stop spread of the bacteria to contact persons. Control of pertussis by acellular vaccines is possible to some extent if immunization coverage is high and booster doses are given lifelong. However new vaccines with higher efficacy rates are warranted.

Seroprevalence of Bordetella pertussis antibody in children and adolescents in China

BACKGROUND

This multicenter study was undertaken to investigate the serologic evidence of antibodies to Bordetella pertussis toxin (IgG-PT) in children and adolescents.

METHODS

IgG-PT value in a single serum collected from 1616 children and adolescents was measured by enzyme-linked immunosorbent assay in the Food and Drug Administration (FDA)-units per milliliter from November 2008 to October 2009. The relationship between time since infection and IgG anti-PT levels were analyzed and the estimated age-specific incidences of infection were calculated.

RESULTS

The sera IgG-PT geometric mean concentrations of the samples were 1.7 FDA-U/mL. The sera protective rates of all the subjects were 6.6% (95% confidential interval [CI]: 5.4%, 7.8%). The rates in the group aged 2 years was 9.2% (95% CI: 3.5%, 14.9%), which was significantly higher than in those aged ≥ 3 years (χ = 1615, P = 0.000). In the group aged ≥ 3 years, 4.0% (95% CI: 3.0%, 5.0%) of the individuals tested showed an IgG-PT level ≥ 40 FDA-U/mL, which was equivalent to an estimated incidence of B. pertussis infection of 7000 (95% CI: 5300, 8800) per 100,000 population per year in the year before serum sampling. There were 2 peaks of estimated incidence. One peak incidence of 9100 (95% CI: 4300, 14000) per 100,000 population per year was found in the population aged >6 to 8 years. Another peak was in the population of 12- to 20-year olds with the estimated incidence of 14,600 (95% CI: 9100, 20100) per 100,000 per year.

CONCLUSIONS

The levels of protective antibodies against pertussis were very low in the immunized children aged 2 to 20 years. A booster dose of immunization for older children or adolescents should be an urgent priority. Moreover, using enzyme-linked immunosorbent assay to determine the efficiency of vaccines and even to obtain the serodiagnosis would be beneficial in controlling pertussis.

Tdap5 vaccine (Covaxis): a review of its use as a single-booster immunization for the prevention of tetanus, diphtheria, and pertussis in children (aged 4 years), adolescents, and adults

Covaxis (also licensed as Triaxis or Adacel in individual countries) is a combined tetanus toxoid, reduced diphtheria toxoid, five component acellular pertussis (namely detoxified pertussis toxin, filamentous hemagglutinin, pertactin, and fimbriae types 2 and 3) vaccine for the prevention of diphtheria, tetanus, and pertussis. It is approved for use in Europe as a single intramuscular booster dose in children (aged ≥ 4 years), adolescents, and adults, and in the US it is approved for use in individuals aged 11-64 years. In large, randomized, controlled clinical trials conducted in the UK and North America, a single intramuscular booster dose of Covaxis induced robust immune responses for all of its component antigens when given to children (aged ≥ 4 years), adolescents, and adults. In addition, Covaxis vaccine was safe and generally well tolerated in terms of solicited and unsolicited local injection-site and systemic adverse events, most of which were of mild intensity and resolved without sequelae. Furthermore, the immunogenicity of each individual component and the reactogenicity of Covaxis vaccine in children, adolescents, and adults was generally similar to that of comparator vaccines. Despite being a vaccine-preventable disease and having >90% primary vaccination coverage worldwide, pertussis remains uncontrolled, particularly amongst adolescents and adults. Given the changing epidemiology of pertussis and the requirement to reduce infection in adolescents and adults (including healthcare workers) and thereby prevent transmission of the disease from these individuals to very young infants, the new 'cocoon strategy' recommended in current vaccination guidelines has become a key strategy in the management of morbidity and mortality associated with pertussis. This strategy focuses on the immunization of healthcare workers, and the parents and family members of infants who are too young to have undergone primary immunization, so as to prevent the transmission of pertussis to these young at-risk infants. The implementation of the 'cocoon strategy' may finally give countries the ability to control pertussis infections in these at-risk infants and ultimately provide the desired herd immunity against pertussis. In line with this strategy, a booster dose of Covaxis vaccine provides a valuable option to reduce pertussis morbidity and mortality, and to maintain seroprotection against diphtheria and tetanus in children (aged ≥ 4 years), adolescents, and adults.

The impact of additional pertussis vaccine doses on disease incidence in children and infants

BACKGROUND

Pertussis remains a cause of considerable morbidity in children worldwide. Due to the resurgence of the disease, two vaccine doses for schoolchildren were added to the routine Israeli schedule. In 2005 a 5th dose was introduced for second-graders (aged 7-8), and in 2008 an additional catch-up dose in the eighth grade (13-14 year-olds).

METHODS

Population-based epidemiologic study of pertussis in the Jerusalem district.

RESULTS

1736 pertussis cases were reported from 1990 to 2009. The pertussis incidence rates increased sharply from 2.6/100,000 in 1990, to 10/100,000 in 2000, peaking at 28.8/100,000 in 2006, then declining to 22/100,000 in 2008 and to 15.7 in 2009 (2006 vs. 2009, p=0.0001). Most cases (74.4%, 1134/1524 during 1998-2009) were under 20 years. Infants under one year had the highest average incidence rate (72.3/100,000; 12.5% of cases); specifically those under 6 months (84.3% of cases under one year). The case distribution among 1-4, 5-9, 10-14, and 15-19 year-olds was: 11%, 18%, 24.1%, and 8.9%. The vaccination status (age-appropriate) was: unvaccinated--19.2%, partially vaccinated--7.6%, and fully vaccinated--73.2%. The overall hospitalization rate was 5.4%; infants--33.5%. Household transmission occurred in 16.1% of cases. The two age groups showing significant decline were children aged 5-9 (61.5% reduction) and 10-14 years (73.9% reduction); there is as yet no significant decline in other age groups.

CONCLUSIONS

The recent marked decline in pertussis incidence among the 5-14 year-olds is encouraging. Young infants still constitute a significant disease burden, and the incidence in this age group should be followed closely.