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

WAO-ARIA consensus on chronic cough - Part III: Management strategies in primary and cough-specialty care. Updates in COVID-19

Background

Chronic cough management necessitates a clear integrated care pathway approach. Primary care physicians initially encounter the majority of chronic cough patients, yet their role in proper management can prove challenging due to limited access to advanced diagnostic testing. A multidisciplinary approach involving otolaryngologists and chest physicians, allergists, and gastroenterologists, among others, is central to the optimal diagnosis and treatment of conditions which underly or worsen cough. These include infectious and inflammatory, upper and lower airway pathologies, or gastro-esophageal reflux. Despite the wide armamentarium of ancillary testing conducted in cough multidisciplinary care, such management can improve cough but seldom resolves it completely. This can be due partly to the limited data on the role of tests (eg, spirometry, exhaled nitric oxide), as well as classical pharmacotherapy conducted in multidisciplinary specialties for chronic cough. Other important factors include presence of multiple concomitant cough trigger mechanisms and the central neuronal complexity of chronic cough. Subsequent management conducted by cough specialists aims at control of cough refractory to prior interventions and includes cough-specific behavioral counseling and pharmacotherapy with neuromodulators, among others. Preliminary data on the role of neuromodulators in a proof-of-concept manner are encouraging but lack strong evidence on efficacy and safety.

Objectives

The World Allergy Organization (WAO)/Allergic Rhinitis and its Impact on Asthma (ARIA) Joint Committee on Chronic Cough reviewed the recent literature on management of chronic cough in primary, multidisciplinary, and cough-specialty care. Knowledge gaps in diagnostic testing, classical and neuromodulator pharmacotherapy, in addition to behavioral therapy of chronic cough were also analyzed.

Outcomes

This third part of the WAO/ARIA consensus on chronic cough suggests a management algorithm of chronic cough in an integrated care pathway approach. Insights into the inherent limitations of multidisciplinary cough diagnostic testing, efficacy and safety of currently available antitussive pharmacotherapy, or the recently recognized behavioral therapy, can significantly improve the standards of care in patients with chronic cough.

Bordetella pertussis in School-Age Children, Adolescents and Adults: A Systematic Review of Epidemiology and Mortality in Europe

Pertussis (whooping cough) epidemics persist globally despite high vaccine coverage among infants and young children. The resurgence of pertussis in high-income countries is partly due to waning vaccine immunity, resulting in a pool of unprotected adolescents and adults. However, pertussis is generally less severe in adolescents and adults, and this difference in presentation means it can often be unrecognised by healthcare professionals, meaning that it is largely under-diagnosed in older populations. A systematic search of MEDLINE, EMBASE and BIOSIS was undertaken to identify studies published between 1 January 1990 and 17 June 2019, with information on pertussis epidemiology and mortality in school-aged children, adolescents and adults in Europe. A formal statistical comparison (e.g. using meta-analyses) was not possible because of the mix of methodologies reported. There were 69 epidemiological studies and 19 mortality studies identified for review. Over the past decade, the reported incidence of notified pertussis cases varied widely between European countries, which is likely associated with differences in surveillance systems, diagnostic techniques and reporting regulations. However, several studies show that pertussis is circulating among adolescents and adults in Europe, and although pertussis-related morbidity and mortality are highest in infants, there is evidence that adults aged > 50 years are at increased risk. For example, in a hospital-based surveillance study in Portugal, between 2000 and 2015, 94% of hospitalised pertussis cases were infants aged < 1 year, with a case fatality rate (CFR) of 0.8%; however, among hospitalised adult cases of pertussis, the CFRs were 11.5% (aged 18–64 years) and 17.4% (aged > 65 years). Very few European countries currently include pertussis boosters for adults in the national immunisation strategy. In addition to increasing pertussis vaccination coverage in adolescents and adults, mitigation strategies in European countries should include improved diagnosis and treatment in these populations.

A data driven clinical algorithm for differential diagnosis of pertussis and other respiratory infections in infants

Background

Clinical criteria for pertussis diagnosis and clinical case definitions for surveillance are based on a cough lasting two or more weeks. As several pertussis cases seek care earlier, a clinical tool independent of cough duration may support earlier recognition. We developed a data-driven algorithm aimed at predicting a laboratory confirmed pertussis.

Methods

We enrolled children <12 months of age presenting with apnoea, paroxistic cough, whooping, or post-tussive vomiting, irrespective of the duration of cough. Patients underwent a RT-PCR test for pertussis and other viruses. Through a logistic regression model, we identified symptoms associated with laboratory confirmed pertussis. We then developed a predictive decision tree through Quinlan's C4.5 algorithm to predict laboratory confirmed pertussis.

Results

We enrolled 543 children, of which 160 had a positive RT-PCR for pertussis. A suspicion of pertussis by a physician (aOR 5.44) or a blood count showing leukocytosis and lymphocytosis (aOR 4.48) were highly predictive of lab confirmed pertussis. An algorithm including a suspicion of pertussis by a physician, whooping, cyanosis and absence of fever was accurate (79.9%) and specific (94.0%) and had high positive and negative predictive values (PPV 76.3% NPV 80.7%).

Conclusions

An algorithm based on clinical symptoms, not including the duration of cough, is accurate and has high predictive values for lab confirmed pertussis. Such a tool may be useful in low resource settings where lab confirmation is unavailable, to guide differential diagnosis and clinical decisions. Algorithms may also be useful to improve surveillance for pertussis and anticipating classification of cases.

Dynamics of pertussis toxin IgG after symptomatic pertussis in children and adults

BACKGROUND AND AIM

The knowledge of dynamics of pertussis toxin (PT)-IgG after pertussis and the appropriate diagnostic cut-off value is limited. We aimed to describe the dynamics of PT-IgG in children and adults up to three years after symptomatic pertussis.

METHODS

Patients with persistent cough of unknown aetiology were prospectively enrolled 2012-2014. Pertussis was confirmed by culture, PCR and/or serology. The follow-up samples were taken 4-6 weeks, 1, 2 and 3 years after enrolment. PT-IgG kinetics was described by biexponential model.

RESULTS

Pertussis was diagnosed in 22 patients [median (IQR) age 17.7 (8.4-38.6) years]. Adults compared with children had higher peak of the PT-IgG 397 (IQR 374-518) vs 292 (200-363), p = 0.007, longer time to reach peak PT-IgG 16.4 (IQR 15.6-16.8) days vs 13.3 (13.2-13.4) days, p=<0.001 and shorter PT-IgG half-life 24 days (IQR 20-40) and 364 days (IQR 359-486) p < 0.001.

CONCLUSION

After symptomatic pertussis, adults and children have different dynamics of PT-IgG. Clinical trial registry: Not applicable.

A novel multilocus variable-number tandem repeat analysis for Bordetella parapertussis

Purpose. Human-adapted Bordetella parapertussis is one of the causative agents of whooping cough; however, there are currently no genotyping systems with high discriminatory power for this bacterial pathogen. We therefore aimed to develop a multilocus variable-number tandem repeat analysis (MLVA) for human-adapted B. parapertussis.Methodology. Four highly polymorphic variable number tandem repeat (VNTR) loci in the B. parapertussis genome were selected and amplified by multiplex PCR. MLVA was performed based on the number of tandem repeats at VNTR loci. The discriminatory power of MLVA was evaluated with three laboratory reference strains and 50 human isolates of B. parapertussis.Results. Multiplex PCR-based MLVA characterized 53 B. parapertussis reference strains and isolates into 25 MLVA types and the Simpson diversity index was 0.91 (95 % confidence interval, 0.86-0.97). The three reference strains exhibited different MLVA types. Thirty-one Japanese isolates, ten French isolates and three Taiwanese isolates belonged to fourteen, nine and three MLVA types, respectively. In contrast, all five Australian isolates belonged to the same type. Two Japanese isolates collected from patients with known epidemiological links had the same type.Conclusion. Our novel MLVA method has high discriminatory power for genotyping human B. parapertussis. Regarding this organism, this genotyping system is a promising tool for epidemiological surveillance and investigating outbreaks.

Evaluating the role of cough duration in the pertussis case definition among Michigan cases, 2000-2010

Impressive reductions in pertussis have been achieved in the U.S. during the 20th century through childhood vaccination. Over the past two decades, increasing pertussis incidence has highlighted the need for accurate and timely reporting of cases to improve prevention and control efforts. We assessed components of the pertussis case definition, comparing use of clinical characteristics and laboratory results and their effects on internal validity, including an examination of the 2014 infant case definition. All reported pertussis cases in Michigan during 2000–2010 with data on cough length (N = 3310) were analyzed using multivariate statistics to internally validate reported cases, and calculate odds of meeting the clinical case definition, including a cough of at least 14 days. Cough duration of reported cases averaged 32 days and was longer with greater time interval between cough onset and initial presentation to a physician. Only about half of reported cases had positive laboratory results. Among cases seeking medical evaluation prior to meeting the cough duration required to fulfill the clinical case definition, the presence of positive lab results doubled the odds that the cough duration was not met compared to cases without a positive lab test. Clinical characteristics of pertussis are frequently ignored in applying the case classification. Relying solely on laboratory confirmation and disregarding clinical characteristics results in undiagnosed pertussis cases among those who are vaccinated, among adults, and among anyone who delays seeking care. This may prevent use of appropriate prevention and prophylaxis in contacts.

•

Increasing incidence of pertussis in the U.S. makes accurate diagnosis and reporting of cases essential to control efforts.

•

Many pertussis cases with positive laboratory tests sought medical evaluation prior to meeting the cough duration criterion.

•

Clinical characteristics of pertussis are frequently ignored by public health and medical professionals in classifying cases.

•

Laboratory confirmation without accompanying clinical characteristics may result in mis-diagnosis of pertussis.

Pertussis in the Association of Southeast Asian Nations: epidemiology and challenges

Pertussis is a highly infectious respiratory disease caused by Bordetella pertussis. Infants and young children are particularly at risk of severe and life-threatening disease. Infectious older individuals may transmit Bordetella pertussis to unprotected infants. Pertussis control measures have even failed in some countries with high pertussis vaccination coverage rates, leading to increased incidence rates. In 2014, this caused the World Health Organization to declare pertussis resurgent in some countries and led to recommendations regarding pertussis surveillance and national immunization programs. Despite the resurgence of pertussis, epidemiology of the disease in Southeast Asia has received little attention. In this narrative review, we describe pertussis surveillance systems, control measures, epidemiologic trends, and region-specific pertussis research in Southeast Asia. We also make recommendations for the intensification of pertussis surveillance and research in the region.

Pertussis clinical case definition: Time for change in developing countries?

Background

Developing countries still struggle with late detection and mortality from pertussis. A review of clinical case definitions is necessary for early disease detection. This paper aimed to study possible clinical characteristics for earlier pertussis detection in a sporadic setting.

Methods

We conducted a retrospective review of medical and laboratory records in a general paediatric ward of a district hospital in a developing country. Inclusion criteria were all children hospitalised with nasopharyngeal swab taken for Bordetella pertussis. We compared sensitivity and specificity of World Health Organization diagnostic criteria with other clinical characteristics. Polymerase chain reaction Bordetella pertussis was the gold standard used.

Results

Out of 207 eligible admissions, the study retrieved 128 complete records. Approximately half of the children were less than 3 months old. The World Health Organization diagnostic criteria had a low sensitivity (15%), but high specificity (92%). In comparison, combinations that included paroxysmal cough, ill contact and facial congestion had higher sensitivity. Increasing cough duration improved specificity while compromising sensitivity.

Conclusion

Several clinical characteristics such as paroxysmal cough, facial congestion and a history of ill contact have potential for early clinical detection. Conventional emphasis on cough duration may hamper early detection.