[Epidemiology of infant bronchiolitis in France]

Tetramerization of Phosphoprotein is Essential for Respiratory Syncytial Virus Budding while its N Terminal Region Mediates Direct Interactions with the Matrix Protein

It was shown previously that the Matrix (M), Phosphoprotein (P), and the Fusion (F) proteins of Respiratory syncytial virus (RSV) are sufficient to produce virus-like particles (VLPs) that resemble the RSV infection-induced virions. However, the exact mechanism and interactions among the three proteins are not known. This work examines the interaction between P and M during RSV assembly and budding. We show that M interacts with P in the absence of other viral proteins in cells using a Split Nano Luciferase assay. By using recombinant proteins, we demonstrate a direct interaction between M and P. By using Nuclear Magnetic Resonance (NMR) we identify three novel M interaction sites on P, namely site I in the α_N2 region, site II in the 115-125 region, and the oligomerization domain (OD). We show that the OD, and likely the tetrameric structural organization of P, is required for virus-like filament formation and VLP release. Although sites I and II are not required for VLP formation, they appear to modulate P levels in RSV VLPs.Importance Human RSV is the commonest cause of infantile bronchiolitis in the developed world and of childhood deaths in resource-poor settings. It is a major unmet target for vaccines and anti-viral drugs. The lack of knowledge of RSV budding mechanism presents a continuing challenge for VLP production for vaccine purpose. We show that direct interaction between P and M modulates RSV VLP budding. This further emphasizes P as a central regulator of RSV life cycle, as an essential actor for transcription and replication early during infection and as a mediator for assembly and budding in the later stages for virus production.

[Respiratory outcome of bronchopulmonary dysplasia in school-age children]

BACKGROUND

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease of infancy. The influence of its initial severity on long-term respiratory outcome remains uncertain.

OBJECTIVES

The purpose of this study was to examine the impact of "new BPD" on respiratory morbidity as well as respiratory function at rest and during exercise in school-age children.

METHODS

The 93 preterm newborns (<33 weeks gestation) presenting with BPD between 1997 and 2004 at the Rennes University Hospital had been proposed for a specific follow-up program. The children included in this cohort and presenting without severe handicap or motor deficit were eligible for this observational retrospective study. Their standardized clinical evaluation and the results of the pulmonary function tests and cardiopulmonary exercise tests performed between the ages of 7 and 14 years were studied. BPD was considered to be moderate when respiratory or oxygen support continued at 36 weeks gestation with an FiO2 less than 30% and severe when FiO2 was greater than 30%.

RESULTS

Among the 36 children assessed, the initial severity of the BPD was mild in 12 cases, moderate in 12 cases, and severe in 12 cases. The mean age at the time of the pulmonary function test (PFT) was 9.9 (±1.9) years, 19 children (53%) had respiratory symptoms during the year before the test, and six (17%) underwent long-term treatment. The PFT was abnormal for 32 children (89%): 23 showed airway obstruction, 16 hyperinflation, three increases in bronchial reactivity, and two restrictions. The residual volume/total lung capacity ratio was the only parameter related to the severity of BPD (P<0.05). The cardiopulmonary exercise test was given to 35 children: 15 of them had normal exercise ability but with a limited ventilatory reserve.

CONCLUSIONS

Half of the children included in this "new-BPD" follow-up cohort had clinical respiratory morbidity and most of the children followed presented with persistent alterations in pulmonary function tests at school age, which were not associated with significant alterations in the maximum aerobic performance.

Respiratory morbidity of preterm infants of less than 33 weeks gestation without bronchopulmonary dysplasia: a 12-month follow-up of the CASTOR study cohort

The aim of this study was to describe the incidence and risk factors for respiratory morbidity during the 12-month period following the first respiratory syncytial virus (RSV) season in 242 preterm infants [<33 weeks gestational age (GA)] without bronchopulmonary dysplasia and 201 full-term infants (39-41 weeks GA) from the French CASTOR study cohort. Preterm infants had increased respiratory morbidity during the follow-up period compared to full-terms; they were more likely to have wheezing (21% vs. 11%, P = 0·007) and recurrent wheezing episodes (4% vs. 1%, P = 0·049). The 17 infants (14 preterms, three full-terms) who had been hospitalized for RSV-confirmed bronchiolitis during their first RSV season had significantly more wheezing episodes during the follow-up period than subjects who had not been hospitalized for RSV-confirmed bronchiolitis (odds ratio 4·72, 95% confidence interval 1·71-13·08, P = 0·003). Male gender, birth weight <3330 g and hospitalization for RSV bronchiolitis during the infant's first RSV season were independent risk factors for the development of wheezing episodes during the subsequent 12-month follow-up period.

Prospects for molecular point-of-care diagnosis of lower respiratory infections at the hospital’s doorstep

Now that molecular assays have been simplified, they can be performed at the point of care (POC). As we aimed to evaluate POC detection of respiratory viruses, we have collected studies on the molecular detection of viruses in children and adults with a well-characterized diagnosis, made in hospital settings, of community-acquired acute bronchiolitis (AB) or pneumonia (CAP). We then present the epidemiological issues for each disease. The prevalence of 18 virus species and types was determined separately for each disease, virus by virus. Overall, the median detection rate of viruses was 90% (interquartile range [IQR]: 69.25–93.5%) and 71.8% (IQR: 69.25–74.25%) in children with AB and CAP, respectively, and 24.5% (IQR: 20–30%) in adults with CAP. The observations on the relationship between virological findings and severity of disease were conflicting in AB, while those for influenza-related CAP were significantly associated with high morbidity/mortality. There is evidence supporting the suggestion that molecular POC detection of targeted pathogens could optimize bed management in emergency departments, guide anti-infective therapies and prevent nosocomial outbreaks. However, further investigations are required to determine when the detection of a large panel of viruses should be processed in clinical practice.

Hospitalizations for respiratory syncytial virus bronchiolitis in preterm infants at <33 weeks gestation without bronchopulmonary dysplasia: the CASTOR study

This study was conducted during the 2008–2009 respiratory syncytial virus (RSV) season in France to compare hospitalization rates for bronchiolitis (RSV-confirmed and all types) between very preterm infants (<33 weeks' gestational age, WGA) without bronchopulmonary dysplasia and full-term infants (39–41 WGA) matched for date of birth, gender and birth location, and to evaluate the country-specific risk factors for bronchiolitis hospitalization. Data on hospitalizations were collected both retrospectively and prospectively for 498 matched infants (249 per group) aged <6 months at the beginning of the RSV season. Compared to full-term infants, preterm infants had a fourfold [95% confidence interval (CI) 1·36–11·80] and a sevenfold (95% CI 2·79–17·57) higher risk of being hospitalized for bronchiolitis, RSV-confirmed and all types, respectively. Prematurity was the only factor that significantly increased the risk of being hospitalized for bronchiolitis. The risk of multiple hospitalizations for bronchiolitis in the same infant significantly increased with male gender and the presence of siblings aged ⩾2 years.

Paediatric intensive care admissions for respiratory syncytial virus bronchiolitis in France: results of a retrospective survey and evaluation of the validity of a medical information system programme

The purpose of this study was to describe the characteristics of patients with bronchiolitis admitted to a paediatric intensive care unit (PICU), and to evaluate a national registry of hospitalizations (Programme de Médicalisation des Systèmes d'Information; PMSI) as a potential source of epidemiological data. Of the 49 French PICUs invited to take part in a retrospective survey of children aged <2 years who were hospitalized during the 2005–2006 epidemic season, 24 agreed to participate. Overall, 467 children were enrolled: 75% were aged <2 months, 76% had positive respiratory syncytial virus (RSV) tests, 34·9% required non-invasive ventilation, 36·6% were mechanically ventilated, and six infants died. The main neonatal characteristics were: prematurity (31·9%), respiratory disease (16·5%), congenital heart disease (6·4%), receiving mechanical ventilation (11·6%), and bronchopulmonary dysplasia at day 28 (3·8%). For bronchiolitis episode, the kappa coefficient between the survey and PMSI data was good only for mechanical ventilation (0·63) and the death rate (0·86).

[Bronchiolitis viruses]

In Normandy (France), human respiratory syncytial virus (hRSV) was detected in 64.1% of acute bronchiolitis in hospitalized children, rhinovirus in 26.8%, human metapneumovirus (hMPV) in 7.6%, and parainfluenza virus (PIV) in 3.4%. The viruses causing acute bronchiolitis in the community were hRSV (42%), rhinovirus (19.5%), coronavirus (8%), PIV (3.5%), and hMPV (2.5%). In 53.7% of the cases, hRSV infected infants (86.9%), 53.7% being less than 6 months of age. Of the hRSV cases, 48.2% were detected in November and December and 44.5% in January and February. The hRSV epidemic started the 1st or 2nd week of October but it varied from one year to another and from one region to another. hRSV acute bronchiolitis increased from 261 cases in epidemics from 1999-2003 to 341 cases from 2004-2009. Rhinoviruses gave acute bronchiolitis in 38.4% of cases. A rate of 54.6% of viruses was detected in September and October and 38.5% in March and April. A total of 34.2% of infected infants were under 6 months of age, 37.8% between 6 months and 2 years, and 19.5% were between 2 and 5 years old. hMPV epidemics coincided with hRSV epidemics, but they accounted for one-sixth the number of cases. HMPV infected infants (74%) who were older than those infected with hRSV, and the diagnosis was bronchiolitis (59%) and pneumonia (17%). PIV infections (about 100 cases per year) included PIV3 (62.7%), PIV1 (25.3%), and PIV2 (7.3%). PIV1 infections occurred every 2 years in the fall. PIV3 infections were observed every year during the fall and winter, with peaks of infections in the spring in the years without PIV1. There were acute cases of bronchiolitis in 29.8% of PIV3 infections and 18.3% in PIV1 infections.

Burden of infant bronchiolitis: data from a hospital network

In France, surveillance of bronchiolitis is based on a pilot network of hospital emergency departments. The study was a 1-year observational study (2007-2008) carried out in a central region of metropolitan France. The hospitalization rate for bronchiolitis was 17.7/1000 children aged <1 year and the estimated prevalence of bronchiolitis ranged from 17.7% to 34.4% in children aged <1 year. Such a network constitutes a valuable tool to estimate the dynamic and the burden of infant bronchiolitis.

[Methodological aspects of economic evaluation in pediatrics: illustration by RSV infection prophylaxis in the French setting]

The methodological approach of the economic evaluation of drugs in pediatrics is illustrated by the case study of the prophylaxis for RSV infections using palivizumab in the French setting. The indications for the reimbursement of this treatment have been restricted to premature children with bronchopulmonary dysplasia (BPD) or hemodynamically significant congenital-heart disease. A model was developed primarily using the results of the pivotal clinical studies on palivizumab. Unit costs were estimated (2006 values) in both societal and payer's perspectives. An assumption was made and discussed on the benefits of the prophylaxis on mortality. Based on the different data available and the estimated costs and benefits, different cost-effectiveness ratios (CERs) were estimated from both the society's and payer's points of view. A discount rate of 3% was applied to benefit. The CER obtained in the most unfavorable case is considered acceptable for the innovative-medical technologies in the French-healthcare system. Some of the parameters used by the model will be illustrated from the EPIPAGE study data from 2 of the 9 regions involved in this study: this evaluation suggests that the children not having an RSV infection during their 1st year of life will continue to require significantly fewer hospitalizations in the following years. These additional evaluations also suggest that the model overestimates the costs of the treatment with regard to the true medical situation. This could be explained by the model not using the children's exact weight or the real number of injections because the children had been discharged from the maternity ward based on their date of birth and the epidemic period. In spite of these factors, RSV prophylaxis using palivizumab in premature children with BPD or hemodynamically significant congenital-heart disease can be considered cost-effective in France.

Impact of consensus development conference guidelines on primary care of bronchiolitis: are national guidelines being followed?

AIM

To measure the impact of French national consensus guidelines on the clinical practices of primary care paediatricians and general practitioners.

DESIGN

Non-randomized intervention study, with a first survey 1 year before the consensus development conference and a second survey 1 year after.

INTERVENTION

Implementation of bronchiolitis management guidelines through the medical press and the Internet.

SUBJECTS

Paediatricians and general practitioners treating infants 1 year of age and under consulting for a first-time episode of bronchiolitis.

RESULTS

Ninety-three doctors and 510 infants were included during the first phase of the study and 96 doctors and 394 infants during the second phase. This study showed a slight increase in adherence to the guidelines for non-validated drugs (6.6% adherence before and 14.3% after), general advice (29.0% adherence before and 57.1% after) and flow modulation respiratory physical therapy (91.9% adherence before and 98.8% after). Increase in adherence to guidelines for other practices, that is, hospitalization, prescribing antibiotics and complementary examinations, was not statistically significant. Adherence to the guidelines on providing general advice increased the most between the two studies.

CONCLUSION

The guidelines helped practitioners evolve slightly in their approach to the treatment of bronchiolitis. Non-validated drugs remain frequently used. Additional resources for implementing the guidelines should be provided to improve primary care doctors' practices.

Bronchiolitis due to respiratory syncytial virus in hospitalized children: a study of seasonal rhythm

AIM

The objective of this study was to describe the rhythm of respiratory syncytial virus (RSV) bronchiolitis seasonal outbreaks in hospitalized children.

METHODS

Data was collected from 1324 patients, who were admitted to our hospital with bronchiolitis, over an 11-year period, from 1994 to 2004. The epidemic onset was established according to the epidemic index. Virological diagnosis was made with immunofluorescent assay from nasopharyngeal washings. Rhythm study was carried-out by spectral analysis with the fast-Fourier transformed and cosinor method.

RESULTS

Epidemics begin in September (45%) and October (55%); the highest peak was observed in January, the minimum in August and the end in February (73%), March (18%) and April (9%). When the epidemic outbreak begins sooner, the end is sooner as well. Epidemic onset varies but not its length and the onset was less variable than its conclusion. Spectral analysis showed a 12-months cyclic period along the study years and cosinor analysis demonstrated significant circannual rhythm. When data was segregated by long and short hospital stay, no significant differences were found between the rhythms. Comorbid association among bronchiolitis, otitis and gastroenteritis was very common.

CONCLUSION

Bronchiolitis epidemics onset and conclusion varies along time years in hospitalized infants and showed circannual rhythmicity with a 12-months period.

[Simultaneous outbreaks of rotavirus and respiratory syncytial virus in Paris: a 12-year survey]

OBJECTIVE

The authors had for aim to study the coincidence of RSV and rotavirus epidemic peaks in pediatric patients hospitalized in the Paris area.

METHODOLOGY

A retrospective hospital-based monocentric cohort study was made over a 12-year period (1993-2004). Clinical and laboratory findings were prospectively collected on admission.

RESULTS

Three thousand and four hundred ninety-six stool samples were positive for rotavirus; 3,507 nasopharyngeal aspirates were positive for RSV. The coincidence of epidemic peaks for both viruses in November, December, and January was observed during the 12 years of the study.

CONCLUSION

The exact coincidence of winter outbreaks of RSV and rotavirus is a characteristic of the Paris area. It contributes to increase overcrowding in pediatric units and nosocomial infections.

[Infant bronchiolitis point of care by physicians in the Ile-de-France bronchiolitis network]

OBJECTIVE

The Ile-de-France bronchiolitis network assessment gave us the opportunity to carry out a survey regarding the customary handling of acute bronchiolitis by physicians involved in this network. The aim of this study was to retrieve results relating to season 2003-2004 and to compare them with the September 2000 French consensus conference recommendations.

METHODS

The practitioners engaged using a special form subsequently transmitted to network joint committee collected the clinical and therapeutic data of the patients included in the Network. We analysed 342 exploitable forms.

RESULTS

Analysis of the physicians medications for patients classified as bronchiolitis showed that their behavior was on the whole keeping with the official recommendations. The nearly systematic prescription of specific respiratory physiotherapy (increase in expiratory flow) satisfies the expectations of the French consensus conference. Likewise, treatments such as bronchodilator or corticoids that are not recommended were prescribed only in approximately 1/4 of cases. Abstention from all medical treatment was found in only 41% of cases classified as bronchiolitis. However, in considering only the first episode of acute bronchiolitis, this rate increased to 54,3%. Short-acting bronchodilator usage may appear legitimate as a therapeutic test of reversibility. In our study, 1/3 of patients with bronchiolitis treated by bronchodilator underwent a second episode and 80% of them were older than 6 months.

CONCLUSION

Analysis of the practices of physicians participating in the Bronchiolite Ile-de-France Network proves very positive in light of the comparison with studies prior and subsequent to the consensus conference. In recognition of this, it is necessary to consider the importance of the network's training programs. Beyond the need to go on with the diffusion of the recommendations, it seems desirable to extend them to clinical situations not yet considered, especially recurrent bronchiolitis and infant asthma. Finally, this type of study should be repeated in order to measure the future evolution of medical practices, as well as extended to a larger scope than the Ile-de-France bronchiolitis Network.

Impact de la conférence de consensus sur le traitement ambulatoire des bronchiolites du nourrisson

OBJECTIVE

To assess the impact of guidelines of the consensus conference in September 2000 on the ambulatory management of acute bronchiolitis in infants.

METHODS

Prospective multicenter study, in four hospitals in the North department in France, during three epidemic periods: the winter preceding the consensus conference and the two following winters. All the infants between 30 days and 2 years of age, admitted to an emergency care unit for a first or second episode of bronchiolitis were included. The infants' characteristics and ambulatory treatments prescribed were collected.

RESULTS

Six hundred thirty-eight infants were included: 169 before the conference and 469 after. Seventy-seven percent had consulted previously and a prescription had been drawn-up for 77%. There was no difference in the frequency of drug prescriptions or physiotherapy between the three periods. After the conferences, inhaled beta(2) agonists were still prescribed in 21% of cases, inhaled corticosteroids in 15%, oral corticosteroids in 34%, antibiotics in 53% and mucolytics in 54%. Physiotherapy was prescribed for 58% of the infants.

CONCLUSION

Two years after the consensus conference, the ambulatory treatment of bronchiolitis has no changed, corticosteroids, beta(2) agonists, antibiotics and mucolytics are still prescribed in excess. Further studies, within a few years, are required to reassess the application of the guidelines, not only in outpatient but also in inpatient management.

[Risk factors for early bronchiolitis at asthma during childhood: case-control study of asthmatics aged 4 to 12 years]

The group of general paediatrics of the French Paediatrics Society conducted a case-control study in order to verify the link between the occurrence of an acute bronchiolitis early during the first year of life, more specifically during the first trimester, and asthma during later childhood.

METHODS

Parents of 4-to-12-year-old children answered a questionnaire during a general paediatrics visit. Exposition was attested by a diagnosis of bronchiolitis mentioned on the personal health record of the child. Environmental factors and medical history, obtained from the parents and by checking the health record of the child, were studied using multivariate analysis.

RESULTS

Nineteen paediatricians included 80 children with asthma and 160 controls. Fifty-four per cent of asthmatic children had a medical history of bronchiolitis during the first year of life versus 17% of control children (P < 0.001). Mean age of bronchiolitis occurrence was 6.6 months in both groups (P = 0.98). Multivariate analysis showed that occurrence of bronchiolitis during the first year of life was significantly more frequent in asthmatic children (P < 0.001, OR = 5.6, IC95 = [2.6-11.6]) but this effect was not observed during the first trimester of life.

CONCLUSION

Bronchiolitis during the first year of life was significantly related to later asthma in 4-to-12-year-old children treated by general paediatricians. On the other hand, a very early bronchiolitis during the first trimester of life did not appear, in our set of data, as a contributive factor to explain asthma in later childhood.

[Prospective regional study of an epidemic of respiratory syncytial virus (RSV) bronchiolitis]

This prospective study was designed to identify risk factors associated with admission in pediatric intensive care units (PICU) among infants hospitalized for treatment of RSV induced bronchiolitis. This study was population-based and was conducted in Burgundy, a French region with 1,800,000 inhabitants where passive immunoprophylaxis for RSV bronchiolitis was not set up at the time of the study.

RESULTS

From December 1st 1999 to April 30th 2000, 484 infants were hospitalized for RSV bronchiolitis in Burgundy: 19.6% were born prematurely (gestational age [GA] below 37 weeks) and at admission, 68.3% had a postnatal age below six months (mean = 5 +/- 5.9 months; median value = 3 months). The duration of hospitalization was 7.3 +/- 12.4 days (median value = 6 days). Among the 484 infants, 31 (6.4%) needed admission in PICU, eight needed mechanical ventilation (1.7%) and one died (0.2%). Univariate analysis identified anamnestic risk factors associated with admission in PICU: prematurity; low birth weight; past history of neonatal respiratory distress syndrome (RDS); mechanical ventilation for RDS treatment; bronchopulmonary dysplasia (BPD) and congenital heart disease. Multivariate analysis identified three independent factors associated with an increased risk for admission in PICU: GA below 32 weeks; RDS and congenital heart disease.

CONCLUSION

This study suggests that population at risk for severe RSV bronchiolitis with PICU admission should include all very preterm infants with RDS whatever the outcome of RDS (with or without BPD). These epidemiological data could be helpful to set up indications for passive immunoprophylaxis of RSV induced bronchiolitis.