[Bronchiolitis viruses]

Predictors of prolonged length of hospital stay and in-hospital mortality in patients aged 1-24 months with acute bronchiolitis in Douala, Cameroon

INTRODUCTION

In Cameroon, acute bronchiolitis has been reported as the third commonest lower respiratory infection and is usually associated with low mortality. Nonetheless, respiratory distress associated with non-adherence to management guidelines can prolong hospital stay. This study aimed to explore predictors of prolonged hospital stay (≥ 5 days) and mortality in patients aged < 2years hospitalised for acute bronchiolitis.

METHODOLOGY

We conducted a retrospective cohort study at three paediatric units in the city of Douala, Cameroon. Factors associated with prolonged hospital stay and mortality were determined using multivariable linear regression model. Threshold for significance was set at p ≤ 0.05.

RESULTS

A total of 215 patients with bronchiolitis were included with mean age of 6.94 ± 5.71 months and M/F sex ratio of 1.39/1. Prolonged hospital stay was reported in 46.98% and mortality in 10.70% of patients hospitalised for bronchiolitis. Factors independently associated with prolonged hospital duration were oxygen administration [b = 0.36, OR = 2.35 (95% CI:1.16-4.74), p = 0.017], abnormal respiratory rate [b = 0.38, OR = 2.13 (1.00-4.55), p = 0.050] and patients presenting with cough [b = 0.33, OR = 2.35 (95% CI: 1.22-4.51), p = 0.011], and diarrhoea [b = 0.71, OR = 6.44 (95% CI: 1.6-25.86), p = 0.009] on admission. On the other hand, factors independently associated with mortality were age of the patient [b= -0.07, OR = 0.84 (95% CI: 0.74-0.97), p = 0.014] and oxygen administration [b = 1.08, OR = 9.64 (95% CI:1.16-79.85), p = 0.036] CONCLUSION: Acute bronchiolitis represented 1.24% of admissions and was common in the rainy season, in males and 3-11-month-old patients. Management guidelines were poorly respected. Prolonged length of stay was reported in half of the patients hospitalized and mortality was high, especially in younger patients and in patients receiving oxygen.

Epidemiological and clinical characteristics of human rhinovirus caused bronchiolitis in children in Southeast China

BACKGROUND

Human rhinovirus (hRV) is a critical viral pathogen implicated in bronchiolitis in children. However, there is no study on hRV bronchiolitis in children from Southeast China. The aim of this study was to determine the incidence and clinical features of hRV bronchiolitis in Southeast China.

METHODS

The study was carried out in Children's Hospital of Soochow University on children admitted with the diagnosis of bronchiolitis from January 2013 to December 2014. hRV was tested using reverse-transcription polymerase chain reaction.

RESULTS

hRV was identified in 140 of 797 specimens (17.6%). hRV was detected with a highest rate in June and August. The hRV positive rate in patients younger than 6 months of age was significantly lower than that in other age groups (P<0.01). The most common radiological finding was hyperinflation (51.4%). Patients with hRV infection were older and more likely to have eczema than those with RSV.

CONCLUSIONS

The hRV was an important viral pathogen associated with bronchiolitis in children with an epidemic peak in summer. Most of patients were between 6 to 24 months and with a high presence of eczema.

Viral Bronchiolo-Alveolitis From Coronavirus OC43 and Rhinovirus-Simulating SARS-CoV-2 Infection

Viruses are the most common cause of acute lower respiratory tract. The respiratory syncytial virus infection is most commonly associated with viral bronchiolitis. Rhinovirus and coronavirus OC43 are less frequently responsible for lower respiratory tract infections. The virological spectrum has expanded greatly owing to the development of molecular biology techniques. We report the clinical case of a four-month-old infant who presented with acute lower respiratory infection with coronavirus OC43 (HCoV-OC43) and rhinovirus complicated by a particularly extensive spontaneous pneumomediastinum.

Rhinovirus Infection and Familial Atopy Predict Persistent Asthma and Sensitisation 7 Years after a First Episode of Acute Bronchiolitis in Infancy

Background: We set out to assess the risk factors for asthma outcome in a cohort of infants who experienced their first episode of acute bronchiolitis. Methods: A cohort of 222 infants who were included during a first episode of acute bronchiolitis was prospectively followed. Herein, we present the results of their assessments (symptom history, skin prick tests, specific IgE assay, respiratory function tests) at age seven. Results: Of the 68/222 (30.6%) children assessed at age seven, 15 (22.05%) presented with asthma and were mainly males (p = 0.033), 14 (20%) had respiratory allergies, 17 (25%) presented atopic dermatitis and none had a food allergy. Family history of atopy was associated with asthma and sensitisation to aeroallergens at age seven (p = 0.003, p = 0.007). Rhinovirus (hRV) infection and rhinovirus/respiratory syncytial virus (RSV) co-infection were significantly associated with asthma at age seven (p = 0.035, p = 0.04), but not with the initial severity of bronchiolitis. Eosinophil counts at ages three and seven were significantly higher in the asthmatics (p = 0.01, p = 0.046). Conclusion: Any infant, especially male, presenting a first episode of acute bronchiolitis due to hRV with a family history of atopy should be closely monitored via follow-up due to a higher risk for asthma at school age.

Axonal Transport Enables Neuron-to-Neuron Propagation of Human Coronavirus OC43

Human coronaviruses (HCoVs) are recognized respiratory pathogens for which accumulating evidence indicates that in vulnerable patients the infection can cause more severe pathologies. HCoVs are not always confined to the upper respiratory tract and can invade the central nervous system (CNS) under still unclear circumstances. HCoV-induced neuropathologies in humans are difficult to diagnose early enough to allow therapeutic interventions. Making use of our already described animal model of HCoV neuropathogenesis, we describe the route of neuropropagation from the nasal cavity to the olfactory bulb and piriform cortex and then the brain stem. We identified neuron-to-neuron propagation as one underlying mode of virus spreading in cell culture. Our data demonstrate that both passive diffusion of released viral particles and axonal transport are valid propagation strategies used by the virus. We describe for the first time the presence along axons of viral platforms whose static dynamism is reminiscent of viral assembly sites. We further reveal that HCoV OC43 modes of propagation can be modulated by selected HCoV OC43 proteins and axonal transport. Our work, therefore, identifies processes that may govern the severity and nature of HCoV OC43 neuropathogenesis and will make possible the development of therapeutic strategies to prevent occurrences.IMPORTANCE Coronaviruses may invade the CNS, disseminate, and participate in the induction of neurological diseases. Their neuropathogenicity is being increasingly recognized in humans, and the presence and persistence of human coronaviruses (HCoV) in human brains have been proposed to cause long-term sequelae. Using our mouse model relying on natural susceptibility to HCoV OC43 and neuronal cell cultures, we have defined the most relevant path taken by HCoV OC43 to access and spread to and within the CNS toward the brain stem and spinal cord and studied in cell culture the underlying modes of intercellular propagation to better understand its neuropathogenesis. Our data suggest that axonal transport governs HCoV OC43 egress in the CNS, leading to the exacerbation of neuropathogenesis. Exploiting knowledge on neuroinvasion and dissemination will enhance our ability to control viral infection within the CNS, as it will shed light on underlying mechanisms of neuropathogenesis and uncover potential druggable molecular virus-host interfaces.

[Anemia, a new severity factor in young infants with acute viral bronchiolitis?]

INTRODUCTION

The role of anemia is raised as a risk of low respiratory infection of the child, but there are no data on anemia as a severity factor in acute viral bronchiolitis (AVB) in infants.

METHODS

All infants less than 16 weeks old admitted to Montpellier University Hospital from 2015/10/01 to 2016/04/01 for AVB were included in a retrospective observational study. The primary objective was to determine whether the hemoglobin (Hb) concentration on admission was an independent factor of clinical severity, judged by the modified Wood's clinical asthma score (m-WCAS). The secondary objective was to assess the impact of Hb level on the characteristics of hospitalization, including the type and duration of respiratory support.

RESULTS

The m-WCAS was used at least once during hospitalization in 180 out of 220 patients (82%), making it possible to distinguish patients with mild AVB (maximum m-WCAS<2, n=81) from patients with severe AVB (maximum m-WCAS>2, n=99). A logistic regression model indicated that the Hb concentration, for every 1g/dL decrement, was an independent factor of AVB severity (OR 1.16 [1.03-1.29], P=0.026). A level under 10g/dL on admission was associated with a higher use of continuous positive airway pressure (P<0.001), as well as a longer duration of respiratory support (P=0.01).

CONCLUSION

This study suggested that anemia may influence the clinical expression of AVB in young infants.

[The interactions between microorganisms and the small airways. A paediatric focus]

The spectrum of respiratory viruses is expanding and emerging diseases have been described regularly over the last fifteen years. The origin of these emerging respiratory viruses may be zoonotic (by crossing species barrier, after changes to RNA viruses such as avian influenza virus type A or coronaviruses), or related to the use of new identification techniques (metapneumovirus, bocavirus). The relationship between bronchiolitis and asthma is now better understood thanks to prospective follow up of birth cohorts. The role of rhinovirus has become predominant with respect to respiratory syncytial virus. The identification of predisposing factors immunological, functional, atopic and genetic, for the onset of asthma after rhinovirus infection suggests that viral infection reveals a predisposition rather than itself being a cause of asthma. The role of bacteria in the natural history of asthma is also beginning to be better understood. The results of the COPSAC Danish cohort have shown the frequency of bacterial identification during wheezy episodes before 3 years, and the impact of bacterial colonization at the age of one month on the onset of asthma by age 5 years. The role of bacterial infections in severe asthma in young children is also discussed.

Study and interest of cellular load in respiratory samples for the optimization of molecular virological diagnosis in clinical practice

BACKGROUND

Respiratory viral diagnosis of upper respiratory tract infections has largely developed through multiplex molecular techniques. Although the sensitivity of different types of upper respiratory tract samples seems to be correlated to the number of sampled cells, this link remains largely unexplored.

METHODS

Our study included 800 upper respiratory tract specimens of which 400 negative and 400 positive for viral detection in multiplex PCR. All samples were selected and matched for age in these 2 groups. For the positive group, samples were selected for the detected viral species.

RESULTS

Among the factors influencing the cellularity were the type of sample (p < 0.0001); patient age (p < 0.001); viral positive or negative nature of the sample (p = 0.002); and, for the positive samples, the number of viral targets detected (0.004 < p < 0.049) and viral species.

CONCLUSION

The cellular load of upper respiratory samples is multifactorial and occurs for many in the sensitivity of molecular detection. However it was not possible to determine a minimum cellularity threshold allowing molecular viral detection. The differences according to the type of virus remain to be studied on a larger scale.

Host-microbe interactions in distal airways: relevance to chronic airway diseases

This article is the summary of a workshop, which took place in November 2013, on the roles of microorganisms in chronic respiratory diseases. Until recently, it was assumed that lower airways were sterile in healthy individuals. However, it has long been acknowledged that microorganisms could be identified in distal airway secretions from patients with various respiratory diseases, including cystic fibrosis (CF) and non-CF bronchiectasis, chronic obstructive pulmonary disease, asthma and other chronic airway diseases (e.g. post-transplantation bronchiolitis obliterans). These microorganisms were sometimes considered as infectious agents that triggered host immune responses and contributed to disease onset and/or progression; alternatively, microorganisms were often considered as colonisers, which were considered unlikely to play roles in disease pathophysiology. These concepts were developed at a time when the identification of microorganisms relied on culture-based methods. Importantly, the majority of microorganisms cannot be cultured using conventional methods, and the use of novel culture-independent methods that rely on the identification of microorganism genomes has revealed that healthy distal airways display a complex flora called the airway microbiota. The present article reviews some aspects of current literature on host–microbe (mostly bacteria and viruses) interactions in healthy and diseased airways, with a special focus on distal airways.

Understanding host–microbe interactions in distal airways may lead to novel therapies for chronic airway diseaseshttp://ow.ly/HfENz

[The lung microbiome in 2015: a window on chronic lung diseases]

Recent development of high-throughput sequencing methods has shown that the human respiratory tract (including lower airways) is not sterile as formerly thought, but composed of a previously unappreciated complex microbial community referred as the lung microbiome and composed of bacteria, viruses and fungi. However, many questions remain unresolved, especially in terms of lung microbiome role, its interactions with host but also with environmental pathogens. Although data are still limited, links have already been demonstrated between lung microbiome and chronic respiratory diseases (such as asthma, chronic obstructive pulmonary disease or cystic fibrosis). This lung microbiome appears to play an important role both in disease genesis and evolution, and consequently offers an emerging research field.

Cleavage of a Neuroinvasive Human Respiratory Virus Spike Glycoprotein by Proprotein Convertases Modulates Neurovirulence and Virus Spread within the Central Nervous System

Human coronaviruses (HCoV) are respiratory pathogens that may be associated with the development of neurological diseases, in view of their neuroinvasive and neurotropic properties. The viral spike (S) glycoprotein is a major virulence factor for several coronavirus species, including the OC43 strain of HCoV (HCoV-OC43). In an attempt to study the role of this protein in virus spread within the central nervous system (CNS) and neurovirulence, as well as to identify amino acid residues important for such functions, we compared the sequence of the S gene found in the laboratory reference strain HCoV-OC43 ATCC VR-759 to S sequences of viruses detected in clinical isolates from the human respiratory tract. We identified one predominant mutation at amino acid 758 (from RRSR↓ G₇₅₈ to RRSR↓R₇₅₈), which introduces a putative furin-like cleavage (↓) site. Using a molecular cDNA infectious clone to generate a corresponding recombinant virus, we show for the first time that such point mutation in the HCoV-OC43 S glycoprotein creates a functional cleavage site between the S1 and S2 portions of the S protein. While the corresponding recombinant virus retained its neuroinvasive properties, this mutation led to decreased neurovirulence while potentially modifying the mode of virus spread, likely leading to a limited dissemination within the CNS. Taken together, these results are consistent with the adaptation of HCoV-OC43 to the CNS environment, resulting from the selection of quasi-species harboring mutations that lead to amino acid changes in viral genes, like the S gene in HCoV-OC43, which may contribute to a more efficient establishment of a less pathogenic but persistent CNS infection. This adaptative mechanism could potentially be associated with human encephalitis or other neurological degenerative pathologies.

Human coronaviruses (HCoV) are respiratory pathogens involved in a sizable proportion of common colds. They have over the years been associated with the development of neurological diseases, given their demonstrated neuroinvasive and neurotropic properties. The viral spike (S) glycoprotein appears to be associated with these neurologic features and is a major factor of virulence for several coronavirus species, including HCoV-OC43. To further characterize the role of this protein in neurovirulence and virus spread within the CNS, we sought to identify amino acid residues that may be important for this function. Our data revealed that one of them, G758R, introduces a functional furin-like cleavage site in the S protein (RRSR↓R₇₅₈). This change in S protein mostly impacts neurovirulence, which seems associated with a modified viral dissemination, without significantly affecting its neuroinvasive capacity. This mutation, found in all characterized contemporary human clinical respiratory isolates, underlines previous findings that naturally existing field isolates of HCoV-OC43 variants still possess the capacity to invade the CNS where they could eventually adapt and establish a persistent human CNS infection, a mechanism potentially associated with human encephalitis or neurodegenerative pathologies of unknown etiologies.

[Winter viral ecology in a pediatric intensive care unit: a prospective study]

Le but de cette étude prospective était d’évaluer l’épidémiologie des virus respiratoires chez les enfants hospitalisés dans une unité de réanimation et de soins continus pédiatriques pendant 3 mois d’hiver, en 2012–2013. Ont été inclus tous les enfants admis en réanimation pédiatrique du centre hospitalier universitaire (CHU) de Caen et ayant bénéficié d’une recherche d’infection par un virus respiratoire à partir d’un prélèvement nasal analysé par amplification génique (PCR) multiplex. Sur 105 enfants admis, 84 répondaient aux critères d’inclusion. Trente-sept enfants présentaient un ou plusieurs symptômes respiratoires à l’admission. Cinquante-quatre échantillons étaient positifs (64,3 %) avec 70 virus détectés. Le virus dont la prévalence était la plus élevée était le virus respiratoire syncytial (VRS) (n = 28 ; 40,0 %), suivi par le rhinovirus (n = 24 ; 34,3 %). Parmi les enfants sans symptômes respiratoires, 42,6 % étaient infectés par un ou plusieurs virus. Aucune différence de durée d’hospitalisation, de durée de ventilation mécanique n’a été mise en évidence en fonction du virus détecté. La principale limite de cette étude est l’analyse par PCR, beaucoup plus sensible que d’autres méthodes de détection, notamment chez des sujets asymptomatiques sur le plan respiratoire. Cette étude révèle cependant un taux élevé d’infections respiratoires causées par des virus chez les enfants qui ne présentent pas de symptômes respiratoires à leur admission en unité de réanimation et soins continus. Elle suggère un intérêt du dépistage de ces infections virales à l’admission des enfants et un bénéfice à l’extension des mesures d’isolement pour tous les enfants en réanimation pédiatrique.

Viral etiology and seasonality of influenza-like illness in Gabon, March 2010 to June 2011

Background

Surveillance of influenza-like illness (ILI) in Central Africa began only recently, and few data are therefore available on the circulation of influenza virus and other respiratory viruses. In Gabon, a Central African country, we established a surveillance network in four major towns in order to analyze cases of ILI among patients who visited health centers between March 2010 and June 2011, and to determine the viral etiology.

Methods

Nasal swabs were sent for analysis to the Centre International de Recherches Médicales de Franceville, where they were screened for 17 respiratory viruses in a multiplex real-time reverse transcription polymerase chain reaction for all pathogens according the following pairs: adenovirus/parainfluenza virus 4, respiratory syncytial virus/human metapneumovirus, parainfluenza virus 1/parainfluenza virus 2, pandemic influenza virus A/seasonal influenza virus A (H1N1, H3N2)/seasonal influenza virus B, human coronaviruses 229E/OC43, human coronaviruses NL63/HKU1, rhinovirus/human parechovirus, and enterovirus/parainfluenza virus 3.

Results

We analyzed a total of 1041 specimens, of which 639 (61%) were positive for at least one virus. Three-quarters of the patients were children under five years old. We therefore focused on this age group, in which 68.1% of patients were positive for at least one virus. The most common viruses were adenoviruses (17.5%), followed by parainfluenza viruses (PIVs) 1–4 (16.8%), enteroviruses (EV) (14.7%), respiratory syncytial virus (RSV) (13.5%), and influenza virus (11.9%). The prevalence of some viruses was subject to geographic and seasonal variations. One-third of positive samples contained more than one virus.

Conclusions

Like most studies in the world, the virus PIVs, EV, RSV, Influenza virus, HRV were predominant among children under five years old in Gabon. An exception is made for adenoviruses which have a high prevalence in our study. However adenoviruses can be detected in asymptomatic persons. These finding gave a better knowledge of the circulation and the seasonality of the viruses involved in ILI in Gabon.

[Day-care centers: Sites of viral contact]

La répétition des épisodes infectieux chez les nourrissons placés précocement en collectivités est une évidence. Leur tropisme sur la sphère respiratoire et l’appareil digestif l’est également. Leur probable retentissement au long cours est difficile à évaluer par la rareté des études prospectives. Le risque infectieux est lié en partie au type de structure de garde, ce risque est important dans les premiers mois de fréquentation et conditionne les récidives ultérieures. Les liens de causalité entre infection virale et asthme sont complexes. Les infections virales augmentent le risque d’asthme mais le statut asthmatique augmente aussi le risque de réponses sévères à une infection virale. Alors que les infections acquises dans cet environnement sont majoritairement virales, leur répétition conduit à une utilisation excessive des antibiotiques d’où une pression de sélection microbienne et un retentissement sur le microbiome digestif voire respiratoire.

Broad respiratory virus detection in infants hospitalized for bronchiolitis by use of a multiplex RT-PCR DNA microarray system

Newly available molecular tools allow a sensitive detection of a broad panel of viruses in respiratory tract specimens. In the present study, the application of a multiplex RT‐PCR DNA microarray in diagnosis and epidemiological survey of viral infections in infants hospitalized for bronchiolitis was assessed. One hundred and thirty‐eight nasopharyngeal aspirates collected from October 2007 to September 2008 were tested by direct immunofluorescence and viral culture, a combination of referenced RT‐PCRs and the DNA microarray. One or more viruses were detected in 96, 126 and 126 of the specimens by direct immunofluorescence and viral culture, RT‐PCRs and DNA microarray, respectively (70 vs. 91 vs. 91%, P < 10⁻³). The RT‐PCRs and the DNA microarray yielded concordant results for 99% of specimens and identified mixed viral infections in 85 (62%). The most common associations were: human bocavirus and respiratory syncytial virus (32%), adenovirus and respiratory syncytial virus (30%), and parainfluenza virus type 3 and respiratory syncytial virus (23%). None of the bronchiolitis severity parameters including intensive care unit admission, O₂ supply, O₂ saturation percentage, O₂ length and length of stay at the hospital appeared to be significantly increased in multiple viral infections compared to single viral infections (P > 0.1). In conclusion, the use of this DNA microarray in clinical virology practice allows rapid and accurate identification of common and uncommon viral respiratory pathogens in infants hospitalized for bronchiolitis. It should improve the clinical management, the epidemiological survey, and the prevention of the nosocomial transmission of respiratory viruses in pediatric wards. J. Med. Virol. 84:979–985, 2012. © 2012 Wiley Periodicals, Inc.