Rediscovering Pertussis

The incidence, duration, risk factors, and age-based variation of missed opportunities to diagnose pertussis: A population-based cohort study

OBJECTIVE

To estimate the incidence, duration and risk factors for diagnostic delays associated with pertussis.

DESIGN

We used longitudinal retrospective insurance claims from the Marketscan Commercial Claims and Encounters, Medicare Supplemental (2001-2020), and Multi-State Medicaid (2014-2018) databases.

SETTING

Inpatient, emergency department, and outpatient visits.

PATIENTS

The study included patients diagnosed with pertussis (International Classification of Diseases [ICD] codes) and receipt of macrolide antibiotic treatment.

METHODS

We estimated the number of visits with pertussis-related symptoms before diagnosis beyond that expected in the absence of diagnostic delays. Using a bootstrapping approach, we estimated the number of visits representing a delay, the number of missed diagnostic opportunities per patient, and the duration of delays. Results were stratified by age groups. We also used a logistic regression model to evaluate potential factors associated with delay.

RESULTS

We identified 20,828 patients meeting inclusion criteria. On average, patients had almost 2 missed opportunities prior to diagnosis, and delay duration was 12 days. Across age groups, the percentage of patients experiencing a delay ranged from 29.7% to 37.6%. The duration of delays increased considerably with age from an average of 5.6 days for patients aged <2 years to 13.8 days for patients aged ≥18 years. Factors associated with increased risk of delays included emergency department visits, telehealth visits, and recent prescriptions for antibiotics not effective against pertussis.

CONCLUSIONS

Diagnostic delays for pertussis are frequent. More work is needed to decrease diagnostic delays, especially among adults. Earlier case identification may play an important role in the response to outbreaks by facilitating treatment, isolation, and improved contact tracing.

The Neonatal Immune System and Respiratory Pathogens

Neonates are more susceptible to some pathogens, particularly those that cause infection in the respiratory tract. This is often attributed to an incompletely developed immune system, but recent work demonstrates effective neonatal immune responses to some infection. The emerging view is that neonates have a distinctly different immune response that is well-adapted to deal with unique immunological challenges of the transition from a relatively sterile uterus to a microbe-rich world, tending to suppress potentially dangerous inflammatory responses. Problematically, few animal models allow a mechanistic examination of the roles and effects of various immune functions in this critical transition period. This limits our understanding of neonatal immunity, and therefore our ability to rationally design and develop vaccines and therapeutics to best protect newborns. This review summarizes what is known of the neonatal immune system, focusing on protection against respiratory pathogens and describes challenges of various animal models. Highlighting recent advances in the mouse model, we identify knowledge gaps to be addressed.

Precision Vaccine Development: Cues From Natural Immunity

Traditional vaccine development against infectious diseases has been guided by the overarching aim to generate efficacious vaccines normally indicated by an antibody and/or cellular response that correlates with protection. However, this approach has been shown to be only a partially effective measure, since vaccine- and pathogen-specific immunity may not perfectly overlap. Thus, some vaccine development strategies, normally focused on targeted generation of both antigen specific antibody and T cell responses, resulting in a long-lived heterogenous and stable pool of memory lymphocytes, may benefit from better mimicking the immune response of a natural infection. However, challenges to achieving this goal remain unattended, due to gaps in our understanding of human immunity and full elucidation of infectious pathogenesis. In this review, we describe recent advances in the development of effective vaccines, focusing on how understanding the differences in the immunizing and non-immunizing immune responses to natural infections and corresponding shifts in immune ontogeny are crucial to inform the next generation of infectious disease vaccines.

Epidemiological and clinical characteristics of pertussis in children and their close contacts in households: A cross-sectional survey in Zhejiang Province, China

BACKGROUND

Despite the expanded immunization programs, the "re-emergence of pertussis" has become a global concern in recent years. At present, the prevalence of pertussis in China is seriously underestimated, and the role of close contact on the disease spreading in children remains unclear.

OBJECTIVES

Our study aimed to investigate pertussis's epidemiological and clinical characteristics in children and their close contacts in households, as well as the antimicrobial resistance of Bordetella pertussis (B. pertussis) in Zhejiang Province, China.

METHODS

We have collected the retrospective and prospective data of children who were suspected of pertussis and their close contacts in households from January 1, 2018, to December 31, 2020, in the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China. Nasopharyngeal swabs were collected and cultured for B. pertussis. Antibiotics susceptibility test was determined by using E-test methods. Clinical information was collected from the medical records systems.

RESULTS

A total of 350 index patients and their 946 family members (close contacts in households) from 350 families were recruited. B. pertussis strains were isolated from 130 (37.1%) index patients and 116 (12.3%) close contacts. 37 index patients had negative culture results for B. pertussis while their close contacts were positive. A higher positive rate was found in female adults than that in male adults (16.3% vs. 5.1%, P < 0.01). The positive rate in index patients from multi-child families was significantly higher than that from one-child families (51.7% vs. 37.7%, P < 0.05). 53.3% of the pertussis patients were under 6 months of age. 98 (75.4%) isolates had MICs ≥ 256 mg/L to erythromycin, azithromycin, and clindamycin, and 127 (97.7%) had MICs < 0.016 mg/L to piperacillin.

CONCLUSION

Infants under 6 months of age are at high risk of pertussis, and close contacts in households are prone to cluster infection. Culture for B. pertussis both in children and their close contacts contributes to improving the diagnosis rate of pertussis in children. Isolates of B. pertussis in China are highly resistant to macrolides.

Prevalence of B. pertussis infection in children with clinically suspected pertussis

BACKGROUND

Pertussis is an important cause of hospitalization in children. Limited data on pertussis have been reported from China. The aim of this study was to characterize clinically suspected pertussis attributable to Bordetella pertussis among children and determine factors associated with longer duration of hospital stay in B. pertussis infection.

METHODS

Two hundred and seventeen consecutive children with clinically suspected pertussis were prospectively enrolled in the study between Jan 2016 through Aug 2017. Variables assessed included demographics, clinical symptoms and laboratory findings. Cox proportional hazards regression model were used to predict variables associated with longer duration of hospital stay.

RESULTS

Among the 217 patients with clinically suspected pertussis, B. pertussis was found in 106 (48.8%) patients. Of the 106 children with B. pertussis infection, 63 (59.4%) patients had coinfections with majority due to rhinovirus (HRV) (30.2%), Mycoplasma pneumoniae (29.2%) and human bocavirus (hBoV) (11.3%). Presence of coinfection [odds ratio (OR): 1.73, CI: 1.17-2.54], age ≤ 3 months (OR: 1.51, CI: 1.09 to 2.27), and WBC count ≥30 × 10⁹/L (OR: 1.66, CI: 1.07 to 2.84) were independently associated with a longer hospital stay.

CONCLUSIONS

B. pertussis infection had a high coinfection rate with the majority of coinfections due to HRV, M. pneumoniae and hBoV. Presence of coinfection, Age ≤3 months and WBC count ≥30 × 10⁹/L were associated with a longer hospital stay. Children admitted with pertussis need close monitoring when they had evidence of coinfection, Age ≤3 months, WBC count ≥30 × 10⁹/L.

Pertussis in Latin America: Recent epidemiological data presented at the 2017 Global Pertussis Initiative meeting

The Global Pertussis Initiative (GPI) is an expert scientific forum that publishes consensus recommendations for pertussis monitoring, prevention, and treatment across many regions of the world. Here, we report on the regional 2017 GPI meeting on the Americas, focusing on Latin America. Information on current pertussis epidemiology, surveillance, vaccine strategies, diagnostic capabilities, disease awareness, and major local obstacles was presented by researchers from Argentina, Brazil, Colombia, Costa Rica, El Salvador, Mexico, Peru, Puerto Rico, Uruguay, and Venezuela. Pertussis outbreaks have occurred during the last decade in the majority of participant countries and have been followed by improvements in surveillance. In the countries that introduced maternal immunization during pregnancy, a reduction in the infant case fatality rate has been detected. All countries need to maintain and improve pertussis surveillance to reach primary vaccination coverage >90%. Moreover, countries without maternal immunization programs should strongly consider them.

SEVERE PERTUSSIS IN CHILDHOOD: UPDATE AND CONTROVERSY - SYSTEMATIC REVIEW

Objective:

Through a systematic review, this essay aimed at revising the concepts of severe pertussis, updating the epidemiology, pathophysiology, clinical presentation, antibiotic therapy and auxiliary therapeutic options for symptomatology and complications.

Data sources:

This review considered publications from the last 30years in the databases US National Library of Medicine (PubMed), Scientific Electronic Library Online (SciELO), Literatura Latino-americana e do Caribe em Ciências da Saúde (LILACS), Cochrane, Google Scholar, as well as protocols of the Ministry of Health and recommendations of the Centers for Disease Control and Prevention, related to childhood pertussis (whooping cough), with emphasis on its severe form. This research was based on keywords derived from the terms “pertussis”, “azithromycin”, “antitussives”, “leukocyte reduction” in Portuguese and English. Duplicate studies and those with unavailable full-text were excluded.

Data synthesis:

Among 556 records found, 54 were selected for analysis. Pertussis, as a reemerging disease, has affected all age groups, evidencing the transient immunity conferred by infection and vaccination. Severe cases occur in neonates and infants, with secondary viral and bacterial complications and malignant pertussis, a longside hyperleukocytosis, respiratory failure and shock. Macrolides continue to be the chosen antibiotics, while antitussives for coughing remain without efficacy. The prompt treatment in Intensive Care Units improved the prognostic in severe cases, and transfusion was promising among procedures for leukoreduction.

Conclusions:

Approaching severe pertussis in childhood remains a challenge for diagnostic and therapy, as the available therapeutic options are still unsatisfactory. Strategies of prevention are expected to reduce the occurrence of severe cases, while new studies should confirm the role of auxiliary therapies.

Neonatal Immunity to Bordetella pertussis Infection and Current Prevention Strategies

Bordetella pertussis is the bacterial agent of whooping cough, an infectious disease that is reemerging despite high vaccine coverage. Newborn children are the most affected, not only because they are too young to be vaccinated but also due to qualitative and quantitative differences in their immune system, which makes them more susceptible to infection and severe manifestations, leading to a higher mortality rate comparing to other groups. Until recently, prevention consisted of vaccinating children in the first year of life and the herd vaccination of people directly in touch with them, but the increase in cases demands more effective strategies that can overcome the developing immune response in early life and induce protection while children are most vulnerable.

Pertussis Resurgence: School Nurses as a Safety Net for Children

After a decade of decreases in the incidence of vaccine-preventable diseases, in the late 1980s the incidence began to increase. Four vaccine preventable diseases, including pertussis, caused major epidemics, and children were the most vulnerable during these outbreaks. Due to waning immunity, genomic changes, and inadequate herd immunity in adults, infants and children are at risk for contracting pertussis. Pertussis is a vaccine-preventable disease. Pertussis is difficult to diagnose early because the presentation is similar to common problems such as bronchitis or upper respiratory infections. School nurses should be able to identify signs and symptoms in the earliest stage possible to prevent transmission and refer for treatment early. The purpose of this article is to provide school nurses with information to understand the disease and identify individuals infected with pertussis.

A Bordetella pertussis MgtC homolog plays a role in the intracellular survival

Bordetella pertussis, the causative agent of whooping cough, has the capability to survive inside the host cells. This process requires efficient adaptation of the pathogen to the intracellular environment and the associated stress. Among the proteins produced by the intracellular B. pertussis we identified a protein (BP0414) that shares homology with MgtC, a protein which was previously shown to be involved in the intracellular survival of other pathogens. To explore if BP0414 plays a role in B. pertussis intracellular survival a mutant strain defective in the production of this protein was constructed. Using standard in vitro growth conditions we found that BP0414 is required for B. pertussis growth under low magnesium availability or low pH, two environmental conditions that this pathogen might face within the host cell. Intracellular survival studies showed that MgtC is indeed involved in B. pertussis viability inside the macrophages. The use of bafilomycin A1, which inhibits phagosome acidification, abolished the survival defect of the mgtC deficient mutant strain suggesting that in intracellular B. pertussis the role of MgtC protein is mainly related to the bacterial adaptation to the acidic conditions found inside the of phagosomes. Overall, this work provides an insight into the importance of MgtC in B. pertussis pathogenesis and its contribution to bacterial survival within immune cells.

Social contact patterns of infants in deciding vaccination strategy: a prospective, cross-sectional, single-centre study

Social contact between individuals is believed to be a fundamental cause in the transmission of many respiratory tract infections. Because they have not yet been fully vaccinated, infants are at high risk for contracting whooping cough, influenza and their serious complications. Therefore, determining infant social contact patterns is an important step in protecting them from respiratory tract infection. This study included 1200 healthy infants (<12 months of age). Social contact diaries were used to estimate the frequency and nature of the infants’ social contacts. This survey also gathered information regarding the infants’ respiratory symptoms and their frequency of attendance at crowded places over a period of 1 week. The diary return rate was 83.8% (N = 1006), and there was a total of 4706 contacts reported for these infants. The median daily contact number per capita was 4 (range 1–18). The median number of contacts with adolescents was 0 (range 0–7). Of the infants, 50.3% had contact with non-household individuals. The mothers had the longest contacts with their babies. Contacts with school children, frequency of attendance at crowded places and age were determined to be significant effective factors for reporting respiratory symptoms. Results suggest that school-age siblings and the mothers should be primarily vaccinated, and parents should keep their babies away from crowded places for protecting their infants.

Bartonella Species, an Emerging Cause of Blood-Culture-Negative Endocarditis

Since the reclassification of the genus Bartonella in 1993, the number of species has grown from 1 to 45 currently designated members. Likewise, the association of different Bartonella species with human disease continues to grow, as does the range of clinical presentations associated with these bacteria. Among these, blood-culture-negative endocarditis stands out as a common, often undiagnosed, clinical presentation of infection with several different Bartonella species. The limitations of laboratory tests resulting in this underdiagnosis of Bartonella endocarditis are discussed. The varied clinical picture of Bartonella infection and a review of clinical aspects of endocarditis caused by Bartonella are presented. We also summarize the current knowledge of the molecular basis of Bartonella pathogenesis, focusing on surface adhesins in the two Bartonella species that most commonly cause endocarditis, B. henselae and B. quintana. We discuss evidence that surface adhesins are important factors for autoaggregation and biofilm formation by Bartonella species. Finally, we propose that biofilm formation is a critical step in the formation of vegetative masses during Bartonella-mediated endocarditis and represents a potential reservoir for persistence by these bacteria.

Emerging Infections and Pertinent Infections Related to Travel for Patients with Primary Immunodeficiencies

In today's global economy and affordable vacation travel, it is increasingly important that visitors to another country and their physician be familiar with emerging infections, infections unique to a specific geographic region, and risks related to the process of travel. This is never more important than for patients with primary immunodeficiency disorders (PIDD). A recent review addressing common causes of fever in travelers provides important information for the general population Thwaites and Day (N Engl J Med 376:548-560, 2017). This review covers critical infectious and management concerns specifically related to travel for patients with PIDD. This review will discuss the context of the changing landscape of infections, highlight specific infections of concern, and profile distinct infection phenotypes in patients who are immune compromised. The organization of this review will address the environment driving emerging infections and several concerns unique to patients with PIDD. The first section addresses general considerations, the second section profiles specific infections organized according to mechanism of transmission, and the third section focuses on unique phenotypes and unique susceptibilities in patients with PIDDs. This review does not address most parasitic diseases. Reference tables provide easily accessible information on a broader range of infections than is described in the text.

Ric-8A-mediated stabilization of the trimeric G protein subunit Gαi is inhibited by pertussis toxin-catalyzed ADP-ribosylation

The heterotrimeric G protein subunit Gαi can be activated by G protein-coupled receptors and the cytosolic protein Ric-8A, the latter of which is also known to prevent ubiquitin-dependent degradation of Gαi. Here we show that the amounts of the three Gαi-related proteins Gαi1, Gαi2, and Gαi3, but not that of Gαq, are rapidly decreased by cell treatment with pertussis toxin (PTX). The decrease appears to be due to ADP-ribosylation of Gαi, because PTX treatment does not affect the amount of a mutant Gαi2 carrying alanine substitution for Cys352, the residue that is ADP-ribosylated by the toxin. The presence of endogenous and exogenous Ric-8A increases Gαi stability as shown in cells treated with the protein synthesis inhibitor cycloheximide; however, Ric-8A fails to efficiently stabilize ADP-ribosylated Gαi. The failure agrees with the inability of Ric-8A to bind to ADP-ribosylated Gαi both in vitro and in vivo. Thus PTX appears to exert its pathological effects at least in part by converting Gαi to an unstable ADP-ribosylated form, in addition to the well-known inability of ADP-ribosylated Gαi to transduce signals triggered by G protein-coupled receptors.