Environmental and demographic risk factors for respiratory syncytial virus lower respiratory tract disease

Glucocorticoids for acute viral bronchiolitis in infants and young children

BACKGROUND

Previous systematic reviews have not shown clear benefit of glucocorticoids for acute viral bronchiolitis, but their use remains considerable. Recent large trials add substantially to current evidence and suggest novel glucocorticoid-including treatment approaches.

OBJECTIVES

To review the efficacy and safety of systemic and inhaled glucocorticoids in children with acute viral bronchiolitis.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2012, Issue 12), MEDLINE (1950 to January week 2, 2013), EMBASE (1980 to January 2013), LILACS (1982 to January 2013), Scopus® (1823 to January 2013) and IRAN MedEx (1998 to November 2009).

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing short-term systemic or inhaled glucocorticoids versus placebo or another intervention in children under 24 months with acute bronchiolitis (first episode with wheezing). Our primary outcomes were: admissions by days 1 and 7 for outpatient studies; and length of stay (LOS) for inpatient studies. Secondary outcomes included clinical severity parameters, healthcare use, pulmonary function, symptoms, quality of life and harms.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data on study and participant characteristics, interventions and outcomes. We assessed risk of bias and graded strength of evidence. We meta-analysed inpatient and outpatient results separately using random-effects models. We pre-specified subgroup analyses, including the combined use of bronchodilators used in a protocol.

MAIN RESULTS

We included 17 trials (2596 participants); three had low overall risk of bias. Baseline severity, glucocorticoid schemes, comparators and outcomes were heterogeneous. Glucocorticoids did not significantly reduce outpatient admissions by days 1 and 7 when compared to placebo (pooled risk ratios (RRs) 0.92; 95% confidence interval (CI) 0.78 to 1.08 and 0.86; 95% CI 0.7 to 1.06, respectively). There was no benefit in LOS for inpatients (mean difference -0.18 days; 95% CI -0.39 to 0.04). Unadjusted results from a large factorial low risk of bias RCT found combined high-dose systemic dexamethasone and inhaled epinephrine reduced admissions by day 7 (baseline risk of admission 26%; RR 0.65; 95% CI 0.44 to 0.95; number needed to treat 11; 95% CI 7 to 76), with no differences in short-term adverse effects. No other comparisons showed relevant differences in primary outcomes.

AUTHORS' CONCLUSIONS

Current evidence does not support a clinically relevant effect of systemic or inhaled glucocorticoids on admissions or length of hospitalisation. Combined dexamethasone and epinephrine may reduce outpatient admissions, but results are exploratory and safety data limited. Future research should further assess the efficacy, harms and applicability of combined therapy.

Infectious burden of respiratory syncytial virus in relation to time of birth modifies the risk of lower respiratory tract infection in infancy: the Norwegian Mother and Child Cohort

OBJECTIVE

The risk of respiratory syncytial virus (RSV) infection according to calendar month of birth has previously been demonstrated. We hypothesize that the real-time infectious burden (IB) of RSV, in relation to time and county of birth, modifies the risk of lower respiratory tract infection (LRTI) in infants, an association that has not been investigated previously, and may be used as an alternative measure of RSV risk when drafting RSV immunoprophylaxis guidelines.

METHODS

Thirty thousand eighty-seven pregnancies were included from July 1, 2003, to July 31, 2006. IB was defined by month and county as the number of RSV detections per inhabitant. IB for 5 periods ante- and postnatally was calculated for each child. Outcome variables were maternally reported hospitalization for LRTI before age 6 months and LRTI before age 12 months. Logistic regression was used to estimate associations between IB and LRTI.

RESULTS

The odds of hospitalization for LRTI rise with increased IB the first 3 months after birth. Low IB: odds ratio (OR) 1.17 (95% confidence interval [CI]: 0.98-1.39); medium IB: OR 1.42 (95% CI: 1.21-1.68); high IB: OR 2.51 (95% CI: 2.15-2.94). High IB 3-0 months before birth confers a lower odds of hospitalization for LRTI the first 6 months of life, OR 0.51 (95% CI: 0.43-0.61). Similar results were seen for maternally reported LRTI the first 12 months of life.

CONCLUSIONS

We find an association between real-time RSV infectious burden and LRTI in infancy: high burden before birth is protective and high burden after birth increases the risk.

Risk factors for hospital admission due to acute lower respiratory tract infection in Guarani indigenous children in southern Brazil: a population-based case-control study

OBJECTIVE

To assess risk factors associated with hospital admission due to acute lower respiratory tract infection (ALRTI) in indigenous Guarani children <5 years of age in southern Brazil.

METHODS

Population-based matched case-control study from May 2007 to June 2008 in 81 Guarani villages. Cases were defined as hospital admissions due to confirmed ALRTI. Two controls free from acute respiratory infection, matched according to age, sex and place of residence, were selected for each case at the time of the case's hospitalisation. Both cases and controls were recruited by a surveillance routine established for the study.

RESULTS

The analysis was performed on 120 cases and 201 controls. The risk factors that remained significantly associated with hospitalisation due to ALRTI in the hierarchical multivariate conditional logistic regression were: low stable monthly per capita household income (<US$30.00 = OR: 2.77, IC95% : 1.51-5.10; no income= OR: 1.88, IC95% : 1.02-3.47); large number of persons in the household (6-9 =  OR: 2.03, IC95% : 1.06-3.88; 10-16 =  OR: 5.00, IC95% : 1.81-13.86); indoor exposure to fumes from burning firewood used for cooking (OR: 3.08, IC95% : 1.39-6.84);low maternal age (OR: 2.77, IC95% : 1.42-5.39); and low birthweight (OR: 6.12, IC95% : 1.44-26.13).

CONCLUSION

Acute respiratory infections are a major cause of morbidity and mortality among Guarani children. Our study provides the first evidence about their determinants in indigenous peoples in Brazil that can help to better understand the epidemiology of respiratory infections in indigenous children.

Effects of parental and household smoking on the risk of respiratory syncytial virus (RSV) hospitalisation in late-preterm infants and the potential impact of RSV prophylaxis

OBJECTIVE

To assess the impact of household smoking and palivizumab prophylaxis on the risk of respiratory syncytial virus (RSV) hospitalisation in late-preterm (32-35 weeks' gestational age) infants.

METHODS

Familial smoking and other RSV risk factor data from the FLIP, FLIP-2 and IMpact studies and datasets from France, Germany and Italy, together with palivizumab prophylaxis data from the FLIP-2 and IMpact studies, were analysed using cross-correlation and Bayesian meta-analytical modelling employing Markov Chain Monte Carlo sampling.

RESULTS

There were 2.35 times (95% confidence interval [CI] 1.37-4.02) as many hospitalisations amongst infants from smoking compared with those from non-smoking families. Among non-prophylaxed infants, there were 2.53 times (95% CI 1.27-4.94) as many RSV hospitalisations from smoking than from non-smoking families and that excess hospitalisation was reduced to 1.03 times (95% CI 0.38-2.99) amongst prophylaxed infants. Familial smoking correlates significantly (p < 0.01) with other RSV risk factors: positive correlation with number of school-age siblings, history of family atopy, family wheeze and gestational age; negative correlation with birth weight and breast feeding.

CONCLUSIONS

Late-preterm infants from smoking families appear to be at heightened risk for severe RSV infection requiring hospitalisation of which the risk may be reduced with RSV prophylaxis.

RT-PCR detection of respiratory pathogens in newborn children admitted to a neonatal medium care unit

BACKGROUND

This study aimed to determine the prevalence of respiratory pathogens among newborns admitted to a neonatal medium care unit (NMCU) and to identify clinical predictors.

METHODS

A 1-y observational study was performed of neonates admitted to an NMCU in Amsterdam, The Netherlands. Nasopharyngeal samples were collected for the detection of respiratory viruses and bacteria by real-time PCR (RT-PCR). Cycle threshold (Ct) values were provided to estimate viral load. Predictors for the presence of study pathogens were identified.

RESULTS

From October 2010 through September 2011, 334 neonates (median age 1.3 d, 53.6% male) were included. Overall, 37 respiratory pathogens were detected in 34 children (10.2%): parainfluenza-1 (n = 9), human rhinovirus (n = 7), parainfluenza-3 (n = 6), respiratory syncytial virus (RSV, n = 6), Streptococcus pneumoniae (n = 3), adenovirus (n = 2), human coronavirus (n = 2), influenza A (n = 1), and bocavirus (n = 1). Neonates with higher viral loads (Ct <35; n = 11) were more often clinically ill than those with lower viral loads (Ct ≥35; n = 23). Two variables significantly contributed to the detection of study pathogens: age (odds ratio (OR) 1.21 for each day older; 95% confidence interval 1.12-1.30) and rhinorrhea (OR 6.71; 95% confidence interval 1.54-29.21).

CONCLUSION

Respiratory pathogens seem to play a role in neonates admitted to an NMCU. The influence of respiratory pathogen detection on clinical management remains to be determined.

Clinical and epidemiologic features of respiratory syncytial virus

Since its discovery in 1955, respiratory syncytial virus (RSV) has consistently been noted to be the single most important cause of lower respiratory tract illness in infants <1 year of age. RSV also causes repeat infections and significant disease throughout life. In addition to the young child, persons with compromised immune, pulmonary or cardiac systems, and the elderly have significant risk from infection. Though RSV causes the full spectrum of acute respiratory illnesses, it is most notably associated with signs and symptoms of increased airway resistance manifested as wheezing and, in the young child, diagnosed as bronchiolitis. In temperate climates, RSV occurs as yearly outbreaks usually between late fall and early spring lasting 3-4 months in a community. The timing of outbreaks varies between years and in the same year between regions and even between nearby communities. RSV can be a serious nosocomial pathogen in high risk individuals but nosocomial transmission that can often be prevented with meticulous attention to good infection control practices. High risk groups include the premature infants and persons of any age with compromised cardiac, pulmonary, or immune systems. Risk factors for infection include increased number of children in the household and day care center attendance. There are reasonable estimates of the sizable burden of RSV disease in infants and young children and the elderly but less data on disease in older children, the role of RSV in later reactive airway disease (see chapter by M.T. Lotz et al. , this volume), and RSV-associated mortality in developing countries. The available data on burden of disease suggests there are at least four potential target populations for a vaccine, the young infant, young children >4-6 months of age, pregnant women, and the elderly. A link between infection in the young infant and later reactive airway disease and mortality in developing countries is needed. Each target population has different vaccine safety and efficacy concerns and may warrant a different type of vaccine.

Acute care utilization due to hospitalizations for pediatric lower respiratory tract infections in British Columbia, Canada

BACKGROUND

Pediatric LRTI hospitalizations are a significant burden on patients, families, and healthcare systems. This study determined the burden of pediatric LRTIs on hospital settings in British Columbia and the benefits of prevention strategies as they relate to healthcare resource demand.

METHODS

LRTI inpatient episodes for patients <19 years of age during 2008-2010 were extracted from the BC Discharge Abstract Database. The annual number of acute care beds required to treat pediatric LRTIs was estimated. Sub-analyses determined the burden due to infants <1 year of age and high-risk infants. Population projections were used to forecast LRTI hospitalizations and the effectiveness of public health initiatives to reduce the incidence of LRTIs to 2020 and 2030.

RESULTS

During 2008-2010, LRTI as the primary diagnosis accounted for 32.0 and 75.9% hospitalizations for diseases of the respiratory system in children <19 years of age and infants <1 year of age, respectively. Infants <1 year of age accounted for 47 and 77% hospitalizations due to pediatric LRTIs and pediatric LRTI hospitalizations specifically due to respiratory syncytial virus (RSV), respectively. The average length of stay was 3.1 days for otherwise healthy infants <1 year of age and 9.1 days for high-risk infants (P <0.0001). 73.1% pediatric LRTI hospitalizations occurred between November and April. Over the study timeframe, 19.6 acute care beds were required on average to care for pediatric LRTIs which increased to 64.0 beds at the peak of LRTI hospitalizations. Increases in LRTI bed-days of 5.5 and 16.2% among <19 year olds by 2020 and 2030, respectively, were predicted. Implementation of appropriate prevention strategies could cause 307 and 338 less LRTI hospitalizations in <19 year olds in 2020 and 2030, respectively.

CONCLUSION

Pediatric LRTI hospitalizations require significant use of acute care infrastructure particularly between November and April. Population projections show the burden may increase in the next 20 years, but implementation of effective public health prevention strategies may contribute to reducing the acute care demand and to supporting efforts for overall pediatric healthcare sustainability.

Prospective multicenter study of viral etiology and hospital length of stay in children with severe bronchiolitis

OBJECTIVE

To determine whether hospital length of stay(LOS) for acute bronchiolitis is influenced by the infecting pathogen.

DESIGN

A prospective observational cohort study was performed during 3 consecutive years.

SETTING

Sixteen US hospitals participated in the study.

PARTICIPANTS

Children younger than 2 years hospitalized with bronchiolitis were included.

MAIN EXPOSURE

The results of nasopharyngeal aspirate polymerase chain reaction pathogen testing served as the main exposure.

MAIN OUTCOME MEASURE

Hospital LOS was determined.

RESULTS

Of 2207 participants, 72.0% had respiratory syncytial virus (RSV) and 25.6% had human rhinovirus(HRV); the incidence of each of the other viruses and bacteria was 7.8% or less. Multiple pathogen infections were present in 29.8% of the children. There were 1866 children(84.5%) with RSV and/or HRV. Among these 1866 children, the median age was 4 months and 59.5% were male. The median LOS was 2 days (interquartile range,1-4 days). Compared with children who had only RSV,an LOS of 3 or more days was less likely among children with HRV alone (adjusted odds ratio [AOR], 0.36; 95%CI, 0.20-0.63; P.001) and those with HRV plus non-RSV pathogens (AOR, 0.39; 95% CI, 0.23-0.66; P.001)but more likely among children with RSV plus HRV(AOR,1.33; 95% CI, 1.02-1.73; P=.04), controlling for 15 demographic and clinical factors.

CONCLUSIONS

In this multicenter study of children hospitalized with bronchiolitis, RSV was the most common virus detected, but HRV was detected in one-quarter of the children. Since 1 in 3 children had multiple virus infections and HRV was associated with LOS, these data challenge the effectiveness of current RSV-based cohorting practices, the sporadic testing for HRV in bronchiolitis research, and current thinking that the infectious etiology of severe bronchiolitis does not affect short-term outcomes.

A comparative study of respiratory syncytial virus (RSV) prophylaxis in premature infants within the Canadian Registry of Palivizumab (CARESS)

We examined the dosing regimens, compliance, and outcomes of premature infants who received palivizumab within the Canadian Registry of Palivizumab (CARESS). Infants receiving ≥1 dose of palivizumab during the 2006-2011 respiratory syncytial virus (RSV) seasons were recruited across 30 sites. Respiratory illness events were captured monthly. Infants ≤32 completed weeks gestational age (GA) (Group 1) were compared to 33-35 completed weeks GA infants (Group 2) following prophylaxis. In total, 6,654 patients were analyzed (Group 1, n = 5,183; Group 2, n = 1,471). The mean GA was 29.9 ± 2.9 versus 34.2 ± 2.2 weeks for Groups 1 and 2, respectively. Group differences were significant (all p-values <0.05) for the following: proportion of males, Caucasians, siblings, multiple births, maternal smoking, smoking during pregnancy, household smokers, >5 household individuals, birth weight, and enrolment age. Overall, infants received 92.6 % of expected injections. Group 1 received significantly more injections, but a greater proportion of Group 2 received injections within recommended intervals. The hospitalization rates were similar for Groups 1 and 2 for respiratory illness (4.7 % vs. 3.7 %, p = 0.1) and RSV (1.5 % vs. 1.4 %, p = 0.3). Neither the time to first respiratory illness [hazard ratio = 0.9, 95 % confidence interval (CI) 0.7-1.2, p = 0.5] nor to first RSV hospitalization (hazard ratio = 1.3, 95 % CI 0.8-2.2, p = 0.3) were different. Compliance with RSV prophylaxis is high. Despite the higher number of palivizumab doses in infants ≤32 completed weeks GA, the two groups' respiratory illness and RSV-positive hospitalization rates were similar.

Respiratory syncytial virus infection augments NOD2 signaling in an IFN-β-dependent manner in human primary cells

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants, with remarkable variability in disease severity. An exaggerated proinflammatory response and influx of leukocytes is part of the pathogenesis of severe RSV disease. Here, we show an increase in proinflammatory cytokine production by human immune cells after stimulation with RSV and muramyl dipeptide (MDP), which is recognized by nucleotide-binding oligomerization domain containing 2 (NOD2). PBMCs from Crohn's disease patients homozygous for the 3020insC mutation in the NOD2 gene did not show a synergistic response to stimulation with RSV and MDP, suggesting that NOD2 is essential for the observed synergy. Further experiments aimed at identifying the viral ligand indicated that viral RNA plays an essential role in the recognition of RSV. Stimulation with RSV or Poly(I:C) induced IFN-β expression, which resulted in an increased expression of the viral receptors TLR3 and RIG-I, as well as an increased NOD2 expression. Our data indicate that IFN-β induction by viral RNA is an essential first step in the increased proinflammatory response to MDP. We hypothesize that the enhanced proinflammatory response to MDP following RSV infection may be an important factor in determining the outcome of the severity of disease.

Prevalence and Characteristics of Human Metapneumovirus Infection Among Hospitalized Children at High Risk for Severe Lower Respiratory Tract Infection

BACKGROUND

Human metapneumovirus (HMPV) is a significant cause of respiratory tract infections. Little is known about HMPV in children who are at high risk for lower respiratory tract infection (LRTI).

METHODS

To determine the prevalence of HMPV in high-risk children and to identify HMPV risk factors, children ≤24 months with prematurity, chronic lung disease, and/or congenital cardiac disease who were hospitalized with LRTI were prospectively enrolled. Nasopharyngeal aspirates were tested for HMPV, respiratory syncytial virus (RSV), influenza A and B, and parainfluenza types 1-3. Demographics, medical history, and outcomes for those with HMPV and RSV were compared. A multivariate analysis was performed to determine HMPV risk factors.

RESULTS

Over 4 years, 1126 eligible children were enrolled. Pathogens were identified in 61% of subjects. HMPV was identified in 9.0%, second to RSV (45%). Coinfection with HMPV and RSV occurred in <1% of subjects. Subjects infected with HMPV were older (8.2 vs 4.0 months, P < .001), were born more prematurely (27 vs 33 weeks, P < .001), and more commonly had chronic lung disease (59.3% vs 21.8%, P < .001) compared with subjects infected with RSV. In a multivariate analysis that compared children infected with HMPV to all others, increasing age and household exposure to children ages 6-12 were associated with an increased risk, whereas birth at older gestational age and exposure to children age >12 were associated with a decreased risk.

CONCLUSIONS

HMPV was detected in 9% of high-risk children who were hospitalized with lower respiratory tract disease, representing the second most common virus in this population. Compared with all other subjects (including RSV-infected), subjects infected with HMPV were older but were born more prematurely.

High concentrations of amniotic fluid proinflammatory cytokines in healthy neonates are associated with low risk of respiratory syncytial virus bronchiolitis

BACKGROUND

The burden of respiratory syncytial virus (RSV) bronchiolitis in individual children and their families, the medical system and society is considerable. Mechanisms underlying RSV bronchiolitis in healthy term infants are largely unknown. Sterile intraamniotic inflammation and chorioamnionitis have been associated with increased lung volume and compliance.

OBJECTIVE

The aim of this study was to determine whether high amniotic fluid interleukin-8 (IL-8), and tumor necrosis factor-α protect against RSV bronchiolitis in healthy term infants.

METHODS

We conducted a prospective birth cohort study of healthy term newborns, born after uncomplicated pregnancy. Amniotic fluid was collected during labor. In case of medical attention for respiratory symptoms during the first year of life, a nose-throat swab was taken to establish the presence of respiratory viruses by polymerase chain reaction.

RESULTS

Physician-attended RSV infection was observed in 27 (9.3%) of 292 children at median age 6 months. Amniotic fluid concentrations of IL-8 were higher in children without physician-attended RSV infection than in children with physician-attended RSV infection (11.1 versus 5.5 ng/mL; P = 0.002). Similarly, in children without physician-attended RSV, the proportion of detectable amniotic fluid tumor necrosis factor-α was higher (159/265 [60%] versus 8/27 [30%]; P = 0.002). Among children with physician-attended RSV infection, amniotic fluid IL-8 was inversely correlated to the number of wheezing days during the first year of life (ρ = -0.38; P = 0.048).

CONCLUSIONS

High concentrations of amniotic fluid IL-8 and tumor necrosis factor-α are associated with low risk of RSV bronchiolitis in healthy term infants. We hypothesize that direct exposure of fetal lungs to proinflammatory signals induces local protection against viral infection during infancy.

Sunshine, rainfall, humidity and child pneumonia in the tropics: time-series analyses

Few studies have formally examined the relationship between meteorological factors and the incidence of child pneumonia in the tropics, despite the fact that most child pneumonia deaths occur there. We examined the association between four meteorological exposures (rainy days, sunshine, relative humidity, temperature) and the incidence of clinical pneumonia in young children in the Philippines using three time-series methods: correlation of seasonal patterns, distributed lag regression, and case-crossover. Lack of sunshine was most strongly associated with pneumonia in both lagged regression [overall relative risk over the following 60 days for a 1-h increase in sunshine per day was 0·67 (95% confidence interval (CI) 0·51-0·87)] and case-crossover analysis [odds ratio for a 1-h increase in mean daily sunshine 8-14 days earlier was 0·95 (95% CI 0·91-1·00)]. This association is well known in temperate settings but has not been noted previously in the tropics. Further research to assess causality is needed.

Plasmacytoid dendritic cell interferon-α production to R-848 stimulation is decreased in male infants

Background

Sex differences in response to microbial infections, especially viral ones, may be associated with Toll-like receptor (TLR)-mediated responses by plasmacytoid dendritic cells (pDCs).

Results

In this study, we identified sex differences in human infant pDC interferon-α production following challenge with the TLR7/8 agonist R-848. Male pDC responses were significantly lower than those of females during early infancy. This difference may be attributed to the androgen surge experienced by males during the early infancy period. Pretreatment of human pDCs with dihydrotestosterone produced a significant reduction in interferon-α production following R-848 challenge.

Conclusions

Androgen-mediated regulation of pDC TLR7-driven innate immune responses may contribute to the observed sex differences in response to infections during early infancy.

Prenatal exposure to bisphenol A and child wheeze from birth to 3 years of age

BACKGROUND

Bisphenol A (BPA), an endocrine-disrupting chemical that is routinely detected in > 90% of Americans, promotes experimental asthma in mice. The association of prenatal BPA exposure and wheeze has not been evaluated in humans.

OBJECTIVE

We examined the relationship between prenatal BPA exposure and wheeze in early childhood.

METHODS

We measured BPA concentrations in serial maternal urine samples from a prospective birth cohort of 398 mother-infant pairs and assessed parent-reported child wheeze every 6 months for 3 years. We used generalized estimating equations with a logit link to evaluate the association of prenatal urinary BPA concentration with the dichotomous outcome wheeze (wheeze over the previous 6 months).

RESULTS

Data were available for 365 children; BPA was detected in 99% of maternal urine samples during pregnancy. In multivariable analysis, a one-unit increase in log-transformed creatinine-standardized mean prenatal urinary BPA concentration was not significantly associated with child wheeze from birth to 3 years of age, but there was an interaction of BPA concentration with time (p = 0.003). Mean prenatal BPA above versus below the median was positively associated with wheeze at 6 months of age [adjusted odds ratio (AOR) = 2.3; 95% confidence interval (CI): 1.3, 4.1] but not at 3 years (AOR = 0.6; 95% CI: 0.3, 1.1). In secondary analyses evaluating associations of each prenatal BPA concentration separately, urinary BPA concentrations measured at 16 weeks gestation were associated with wheeze (AOR = 1.2; 95% CI: 1.0, 1.5), but BPA concentrations at 26 weeks of gestation or at birth were not.

CONCLUSIONS

Mean prenatal BPA was associated with increased odds of wheeze in early life, and the effect diminished over time. Evaluating exposure at each prenatal time point demonstrated an association between wheeze from 6 months to 3 years and log-transformed BPA concentration at 16 weeks gestation only.

Down syndrome and hospitalizations due to respiratory syncytial virus: a population-based study

OBJECTIVE

To assess the risk estimates for respiratory syncytial virus (RSV) hospitalization in children with Down syndrome (DS) and the clinical features and severity of RSV lower respiratory tract infection (LRTI) in hospitalized children.

STUDY DESIGN

Statewide hospitalization data for children with DS for 1995 through 2006 from the Colorado Health and Hospital Association database were combined with birth data from the Colorado Department of Public Health and Environment to obtain population-based estimates of RSV LRTI hospitalization for children with DS in the first 2 years of life. RSV hospitalization data for children with DS at the Children's Hospital Colorado for 2000 through 2006 were used to compare the course and severity of hospitalization of DS LRTI admissions with those of matched control subjects.

RESULTS

There were 85 RSV LRTI hospitalizations in 630 children born with DS in Colorado, with 50 having no concurrent underlying conditions identified. Children with DS had a significantly higher risk than did those without DS for being hospitalized with RSV LRTI (OR, 5.99; 95% CI, 6.68-5.38), even in the absence of other underlying conditions (OR 3.5; 95% CI, 3.10-4.12). In the case-control study, children with DS hospitalized for RSV presented more frequently with fever (P = .005), had consolidation reported more often on chest radiography (P = .003), and were given bronchodilator therapy more often during the hospital stay (P = .002).

CONCLUSIONS

Children with DS have a higher risk of being hospitalized with RSV LRTI even in the absence of coexisting risk factors. They present more often with fever and more often have radiographic consolidation detected on chest radiography.

High risk for RSV bronchiolitis in late preterms and selected infants affected by rare disorders: a dilemma of specific prevention

Respiratory syncytial virus (RSV) is the most frequent aetiologic agent that causes bronchiolitis and lower respiratory tract infection in infants. These infections may be severe and even life-threatening in selected high-risk populations. Traditional, well-established, high-risk populations are preterm infants with or without chronic lung disease and children with congenital heart disease. For these children, RSV prophylaxis using palivizumab, a monoclonal anti-RSV humanised antibody against the F-protein of RSV, has proven safe and efficacious in preventing RSV-related hospitalisation. Recently, a number of rare medical conditions have been associated with the risk of severe RSV infections. Evidence of safety and efficacy of RSV prophylaxis in these populations is lacking. Given the low incidence of these conditions, randomised trials are not feasible. A practical, opinion-based approach to this dilemma is offered in this paper. It is proposed that these rare disorders may qualify for RSV prophylaxis if the association between a specific condition and the risk of severe RSV infection is confirmed in at least 3 independent publications, of which at least 1 includes a prospective cohort study. To facilitate pharmaco-economic analyses, at least one of the three studies must also report on the absolute risk of severe RSV infection in the specified illness. The authors believe that qualification criteria will enable caregivers to target RSV prophylaxis more effectively in children with rare conditions and the proposed approach provides direction for future epidemiological studies on the risk of severe RSV infection in children with these uncommon, medical illnesses.

Seasonality of infant feeding practices in three Brazilian birth cohorts

Background We assessed the influence of season of birth on duration of breastfeeding and other feeding patterns in three population-based birth cohort studies in the city of Pelotas, Southern Brazil.

Methods In 1982, 1993 and 2004, all hospital-born children in the city were enrolled in three cohort studies (n = 5914, 5249 and 4287, respectively). Children and their mothers were periodically visited in the first 2 years of life, to collect information on the duration of breastfeeding and the ages at which different types of foods were introduced on a regular basis. Two independent variables were studied: month of birth and mean environmental temperature in the first month of life. Survival analyses and chi-squared tests were used to evaluate the associations. Temperature-based slope indices of inequality were also calculated.

Results Duration of breastfeeding was lower among children born from April to June (months preceding winter) and spending their first month of life in colder temperatures. The influence of season of birth on breastfeeding patterns and the introduction of cow's milk differed according to maternal education, with the strongest effects among children belonging to less educated mothers. Early introduction of fruits (1982 and 1993 cohorts) and vegetables (1982 cohort) were also associated with lower environmental temperature in the first month of life, but not with trimester of birth.

Conclusion Colder temperatures adversely affect duration of breastfeeding and feeding patterns in infancy, especially among the poorest. This finding should be considered in breastfeeding promotion programmes.

Risk factors for severe respiratory syncytial virus lower respiratory tract infection

RSV infection is a leading cause of lower respiratory tract infection, especially in High-risk infants with a history of prematurity, bronchopulmonary dysplasia (BPD), congenital heart disease (CHD), neuromusculair impairment, immunodeficiency, and Down syndrome. Host related risk factors that have been identified to be associated with severe RSV related lower respiratory tract infection include young age below 6 months at the beginning of RSV season, multiple birth, male sex, low socioeconomic status and parental education, crowded living conditions, young siblings, maternal smoking and indoor smoke pollution, malnutrition/small for gestational age, family history of atopy or asthma, low cord serum RSV antibody titers, and living at altitude.Risk factors increasing the risk of acquisition of RSV have been identified to be birth before and/or during RSV season, day care attendance, presence of older siblings in school or day-care, and lack of breast feeding. Some of these risk factors are discussed controversially and some of them are found continuously throughout the literature.Given the high cost of RSV prophylaxis, especially for the large population of late preterm infants, algorithms and risk score systems have been published that could identify high-risk infants for treatment with palivizumab out of this gestational age group. Several models reported on an average sensitivity and specificity of 70 percent and, thus, are helpful to identify infants at high risk for severe RSV infection and need for prophylaxis with palivizumab.

Respiratory syncytial virus infection in children with neuromuscular impairment

Clinically obvious reasons why children with neurological impairment (NMI) may be more severely affected in case of a viral respiratory tract infection include reduced vital capacity due to muscular weakness or spastic scoliosis, disturbed clearance of respiratory excretions (weak coughing and dysphagia), inability to comply actively with physiotherapeutic interventions, recurrent micro-aspirations (gastroesophageal reflux disease, vomiting related to coughing), a history of frequent exposure to antibiotics and health care institutions, colonization with resistant pathogens, impaired immunologic defence mechanisms due to severe malnutrition and cachexia, and early clinical deterioration in case of high fever with metabolic acidosis and hypercapnia, and maybe associated seizures or febrile convulsions.

Data from the literature suggests that in all children with NMI, who have to be hospitalized with severe clinical deterioration due to an airway infection, at least one specimen of nasopharyngeal secretions should be sent as soon as possible to a virologic laboratory to detect viral pathogens. Children with severe NMI and those mechanically ventilated for other reasons being hospitalized during the RSV season must be strictly protected against nosocomial RSV infection by means of standard and droplet precautions. Finally, children with severe NMI and age below 24 months of life should receive passive immunization with palivizumab following international recommendations.

Respiratory syncytial virus load, viral dynamics, and disease severity in previously healthy naturally infected children

BACKGROUND

Respiratory syncytial virus (RSV) disease severity was thought to be a result of host immunopathology but alternatively may be driven by high-level viral replication. The relationships between RSV load, viral clearance dynamics, and disease severity have not been carefully evaluated.

METHODS

Previously healthy RSV-infected children <2 years old were recruited. RSV load was measured in respiratory secretions by fresh quantitative culture over 3 hospital days. Measures of disease severity were hospital admission, duration of hospitalization, requirement for intensive care, and respiratory failure.

RESULTS

Multivariate logistic regression models revealed independent predictors of increased duration of hospitalization: male sex, lower weight, and higher viral load on any day. Viral loads at day 3 were more significantly associated with requirement for intensive care and respiratory failure than were viral loads at earlier time points. Faster RSV clearance was independently associated with shorter hospitalization.

DISCUSSION

These observations challenge the immunopathology-based pathogenesis paradigm. They also have major therapeutic implications, suggesting that application of antiviral agents early in the disease course, even at a time when viral replication is at its highest, might improve subsequent morbidity by significantly lowering viral load and direct viral cytopathic effects, and aborting the potential downstream immunopathology.

Comparison of biomarkers and parent report of tobacco exposure to predict wheeze

OBJECTIVE

To identify the optimal measure of active and passive prenatal tobacco exposure to predict wheeze in early life.

STUDY DESIGN

We conducted a birth cohort study of 398 mother-infant dyads enrolled during the second trimester of pregnancy and followed through age 2 years. We measured tobacco exposure with maternal report, serum cotinine level, and meconium cotinine level. We assessed wheeze with parent report every 6 months. We used a repeated measures logistic regression model.

RESULTS

Of 367 children with respiratory data, 26% percent had parent reported active or passive prenatal maternal tobacco exposure, but cotinine was detected in 61% of mothers during pregnancy. Compared with children of mothers in the fifth percentile of tobacco exposure, children of mothers in the 95th percentile had increased odds of wheeze when exposure was measured with maternal serum cotinine level (adjusted OR, 2.6; 95% CI, 1.3-5.2; P < .006) versus meconium cotinine level (adjusted OR, 2.0; 95% CI, 1.0-4.0; P = .04) and total parent-reported exposure (adjusted OR, 1.7; 95% CI, 1.1-2.7; P = .01).

CONCLUSIONS

Serum cotinine, a biomarker of tobacco exposure, was more strongly associated with wheeze than parent-reported exposure. Studies that rely on parent report of prenatal tobacco exposure may underestimate risk of wheeze.

Impact of respiratory syncytial virus: the nurse's perspective

Respiratory syncytial virus (RSV) is a highly contagious virus, and is the major cause of lower respiratory tract infections in infants and toddlers worldwide. RSV infection poses serious health risks to young children during the first 2 years of life. Several infant populations have been classified as high risk, and additional risk factors are known to increase the likelihood of severe RSV infection. Treatment for active RSV infection is limited to the symptoms of infection rather than the underlying cause; therefore, it is critical to reduce the transmission of RSV. As nurses, we highlight the importance of educating healthcare professionals, both in the hospital and community settings, as well as parents and other caregivers about the risks and outcomes associated with RSV infection, and necessary measures to decrease the risk of infection. We also highlight the importance of the successful identification of those children who are at high risk of RSV infection. RSV prophylaxis (RSVP) with palivizumab has been shown to improve clinical outcome in infants who are considered high risk compared with those who have not received RSVP. The failure of healthcare staff and primary caregivers to protect children against an RSV infection can have lasting detrimental effects on the health and lives of affected children and their families.

The epidemiology of respiratory syncytial virus lower respiratory tract infections in children less than 5 years of age in Indonesia

BACKGROUND

Although the epidemiology of respiratory syncytial virus (RSV) lower respiratory tract infections (LRI) is well known in industrialized countries, the burden in developing Asian countries is not well studied.

METHODS

To define the burden of RSV disease in children <5 years of age in rural and urban Indonesia, infants and children were enrolled from peri-urban and rural subdistricts, in the following 2 cohorts: (a) a cross-sectional cohort of approximately 100 children from each of 2 subdistricts in the following 5 age groups: 3 to 5, 6 to 8, 9 to 11, 12 to 23, and 24 to 48 months; (b) a birth cohort of all newborns in both subdistricts during the 28 months of the study. All subjects were visited weekly at home. Children with World Health Organization-defined LRI or wheezing had a nasal wash for detection of RSV using an enzyme immunoassay and polymerase chain reaction.

RESULTS

Of the 2014 children studied, 1074 were in the cross-sectional and 940 in the newborn cohorts. Of the 802 episodes of LRI, 163 were caused by RSV. The RSV LRI incidence per 1000 child-years (C-Y) was higher in rural areas (57.25 vs. 38.54), P < 0.05. No RSV LRI occurred in the first 2 months of life and the peak incidence was in the 6- to 8-month-old infants (103/1000 C-Y). The rates were lowest in those <6 months, 16.5 per 1000 C-Y, compared with 83.1 per 1000 C-Y in those 6 to 11 months of age (P < 0.001), 66.99 in those 12 to 23 months of age, and 28.1 in 2- to 5-year-olds.

CONCLUSIONS

In Indonesia, the incidence of RSV LRI in the first 6 months of life is relatively low with most disease occurring in older children.

CARESS: the Canadian registry of palivizumab

BACKGROUND

Palivizumab is indicated for respiratory syncytial virus (RSV) prophylaxis in high-risk children. However, relatively little is known about the current use, compliance, and outcomes associated with this medication.

METHODS

A prospective, observational, registry based on 27 sites, with monthly follow-up of infants at high risk for RSV who received at least 1 dose of palivizumab during the 2005-2009 RSV seasons.

RESULTS

A total of 5286 children were enrolled (56.6% male; 71.7% white; average gestational age, 32.1 ± 5.5 weeks). Of them, 3741 patients (70.8%) were prophylaxed for prematurity only, 449 (8.5%) for bronchopulmonary dysplasia/chronic lung disease, 508 (9.6%) for congenital heart disease, and 588 (11.1%) for other reasons. Overall, 19,485 doses were given. On average, infants received 86.0% ± 28.4% of their expected number of injections; 71.2% of infants received their injections in the recommended time periods. Of the 5286 participants enrolled, 308 patients were hospitalized for respiratory tract illness (hospitalization rate, 5.8%). The RSV-hospitalization rate was calculated as 1.38%. Having siblings increased likelihood of hospitalization (66.9% vs. 55.7%, P < 0.005), and was significantly correlated with time to hospitalization in this cohort (P = 0.050).

CONCLUSIONS

The overall RSV-hospitalization rate in our study was within the range found in previous reports (1.3%-5.3%), although it did not mimic the declining rates of the US Palivizumab Outcomes Registry. This could be due to increased testing for RSV when hospitalized and increasing rates of prophylaxis of infants with underlying medical disorders.

Lower respiratory tract infections and gastrointestinal infections among mature babies in Japan

BACKGROUND

Epidemiologic evidence regarding the background factors of childhood infections in Japan is scarce. The aim of the present study was therefore to investigate the rates and associated factors of hospitalization for lower respiratory tract infections (LRTI) and gastrointestinal infections (GII) among children with birthweight ≥ 2500 g and ≥ 37 weeks of gestational age.

METHOD

The data for the study were collected at 18-month health checkups in one city in Japan. The community database included information on the main outcome (past hospitalization) and 16 host, environmental, and parenting factors. The Kaplan-Meier method and log-rank test were used to determine sex differences in hospital admission for infection, and the Cox regression model to analyze sex-specific factors associated with the hospitalization.

RESULTS

The proportion of children who were admitted to hospital before their 18-month checkup was 7.1% for LRTI and 2.2% for GII. Hospital admission for LRTI among boys was higher than girls. Multivariate analysis indicated the following LRTI-associated factors: child-care attendance (hazard ratio [HR]= 1.97) and three or more adults living together (HR = 2.63) for boys; and child-care attendance (HR = 4.30) and two or more children living together (HR = 4.57) for girls. GII-associated factors were maternal age <25 years (HR = 3.45) for boys, and hand washing by caregivers after lavatory use and diaper changing (HR = 6.93) for girls.

CONCLUSIONS

One out of 11 children was hospitalized because of LRTI or GII during their first 18 months, which was associated with a biologic factor (sex), environmental factors (child-care attendance and family size), and parenting practices (shorter duration of exclusive breast-feeding and caregivers' unfavorable hygiene practices).

Household tobacco smoke and admission weight predict severe bronchiolitis in infants independent of deprivation: prospective cohort study

OBJECTIVES

To examine demographic, environmental and clinical factors associated with severe bronchiolitis in infants admitted to hospital and quantify the independent effects of these factors.

DESIGN

Prospective cohort study.

SETTING

Alder Hey Children's Hospital, Liverpool, United Kingdom.

PARTICIPANTS

378 infants admitted to hospital with a diagnosis of bronchiolitis, of whom 299 (79%) were antigen positive to respiratory syncytial virus (RSV).

OUTCOME

Severity of disease during admission, defined as "no need for supplemental oxygen" (reference group), "any need for supplemental oxygen" and "any need for mechanical ventilation".

RESULTS

Univariate analysis found male sex (p = 0.035) and tobacco smoking by a household member (p<0.001) were associated with need for both supplemental oxygen and mechanical ventilation. Premature birth, low gestation, low birth weight, low admission weight and low corrected age on admission were also associated with need for mechanical ventilation (all p≤0.002). Deprivation scores (IMD 2004) were significantly higher in households where a member smoked compared to non-smoking households (p<0.001). The odds of smoking predicted by deprivation were 7 times higher (95%CI (3.59, 14.03)), when comparing the least and most deprived quintiles of the study population. Family history of atopic disease and deprivation score were not associated with severe disease. Multivariate multinomial logistic regression which initially included all covariates, found household tobacco smoking (adjusted OR = 2.45, 95%CI (1.60, 3.74) predicted need for oxygen supplementation. Household tobacco smoking (adjusted OR = 5.49, (2.78, 10.83)) and weight (kg) on admission (adjusted OR = 0.51, (0.40, 0.65)) were both significant predictors in the final model for mechanical ventilation. The same associations and similar size of effects were found when only children with proven RSV infection were included in analysis.

CONCLUSIONS

Low admission weight and householder tobacco smoking increased the risk of severe bronchiolitis in infants admitted to hospital. These effects were independent of a standard deprivation measure. NIHR Study Ref. DHCS/G121/10.

The impact of prophylaxis on paediatric intensive care unit admissions for RSV infection: a retrospective, single-centre study

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections and hospitalizations in children aged < 2 years. The aim of this retrospective, single-centre study was to examine the characteristics of patients admitted to a paediatric intensive care unit (PICU) with RSV infection following the implementation of a RSV prophylaxis programme. Electronic hospital medical records of all PICU admissions for RSV infection were searched from 2003 to 2009. Data on baseline demographics, underlying disease, criteria for hospitalization, respiratory diagnosis and management, complications and palivizumab prophylaxis were collected. A total of 181 patients were admitted with RSV infection, accounting for 5.7% of all admissions. Eighty-four percent were ≤ 2 years of age. Majority (70.2%) had no underlying medical illness, and 79.6% received antibiotics as part of their medical treatment. Comparison of children aged ≤ 2 years and those >2 years revealed that fewer of the younger cohort (20.4% versus 79.3%; p < 0.001) had an underlying medical condition. RSV infection occurred in 3.3% (n = 6) children who had received palivizumab prophylaxis, and there were two deaths. The results indicate that > 88% of all PICU admissions would not qualify for RSV prophylaxis under our established guidelines and 66% of the children aged ≤ 2 years were > 36 weeks gestation and are not currently targeted for prophylaxis. The number of high-risk infants admitted to PICU with RSV infection has likely plateaued, and further reductions in admission rates may only be realised with the use of universal, vaccine immunization programmes.

Viral and atypical bacterial detection in acute respiratory infection in children under five years

Background

Acute respiratory infection (ARI) is a leading cause of morbidity and mortality in children worldwide. This study aimed to determine the viral and atypical bacterial causes of different severities and clinical manifestations of ARI in preschool children from low-income families in North-East Brazil.

Methods

Clinical/demographic data and nasopharyngeal aspirates (NPA) were prospectively collected from children <5 years presenting with ARI over one year to a paediatric A&E department. Disease severity was grouped according to presence of lower respiratory tract signs, need for hospital admission and need for oxygen. Clinical manifestation of ARI was based on discharge diagnosis from hospital with four conditions predominating: bronchiolitis, pneumonia, episodic viral wheeze/asthma and upper respiratory tract infection. Multiplex PCR was used to detect 17 common respiratory viral and atypical bacterial pathogens in NPA.

Findings

407 children with a median age of eight months were recruited. Pathogens were detected in 85·5% samples with co-infection being particularly common (39·5%). Respiratory Syncytial Virus (RSV; 37%), Adenoviruses (AdV; 25%), Rhinoviruses (hRV; 19%), Bocavirus (hBoV; 19%), human Meta-pneumovirus (hMPV; 10%) and Mycoplasma pneumoniae (Mpp; 10%) were most prevalent. Detection and co-infection rates were similar in all severities and clinical manifestations of ARI apart from RSV, which was associated with more severe disease and specifically more severe cases of bronchiolitis, and Mpp, which was associated with more severe cases of pneumonia. Mpp was detected in 17% of children admitted to hospital with pneumonia.

Interpretation

This study underlines the importance of viral and atypical bacterial pathogens in ARI in pre-school children and highlights the complex epidemiology of these pathogens in this age group. Generally, viruses and atypical bacteria were detected in all severities and clinical manifestations of ARI but RSV and Mpp were associated with more severe cases of bronchiolitis and pneumonia respectively.

Serum vitamin D concentrations and associated severity of acute lower respiratory tract infections in Japanese hospitalized children

BACKGROUND

Vitamin D is an immunomodulatory molecule related to innate immunity that may contribute to the increased occurrence of acute lower respiratory infection (ALRI) in children, one of the most common reasons for hospitalization and intensive care unit admission. In the present study, the association between vitamin D deficiency and the severity of respiratory infection was evaluated by determining serum concentrations of 25-hydroxyvitamin D (25(OH)D) in a group of hospitalized children with ALRI.

METHODS

Of the 28 children admitted to Nihon University Nerima-Hikarigaoka Hospital with ALRI over the period November 2008–May 2009, 26 were diagnosed as having bronchiolitis and two were found to have pneumonia. A competitive protein binding radioimmunoassay was used to determine serum 25(OH)D concentrations.

RESULTS

Mean 25(OH)D concentrations in breast-fed children with ALRI (n = 7) were significantly lower than those in children with ALRI who were bottle fed/weaned (n = 6) or on a regular diet (n = 15; 14.6 ± 9.7, 28.9 ± 6.9 and 24.6 ± 8.8 ng/mL, respectively). There was a significant correlation between vitamin D deficiency (<15 ng/mL) and the need for supplementary oxygen and ventilator management.

CONCLUSION

Significantly more children with ALRI who needed supplementary oxygen and ventilator management were vitamin D deficient. These findings suggest that the immunomodulatory properties of vitamin D may influence the severity of ALRI.

A decade of respiratory syncytial virus epidemiology and prophylaxis: translating evidence into everyday clinical practice

Respiratory syncytial virus (RSV) is a common infection in infancy, with nearly all children affected by two years of age. Approximately 0.5% to 2.0% of all children are hospitalized with lower respiratory tract disease, of which 50% to 90% have bronchiolitis and 5% to 40% have pneumonia. Morbidity and mortality are highest in children with nosocomial infection and in those with underlying medical illnesses such as cardiac and chronic lung disease. Aboriginal children residing in remote northern regions are specifically considered to be at high risk for hospitalization due to RSV infection. Thorough hand washing and health education are the principal strategies in primary prevention. In the absence of a vaccine, palivizumab prophylaxis is currently the best intervention to reduce the burden of illness and RSV-related hospitalization in high-risk children. Health care professionals should provide palivizumab prophylaxis cost effectively in accordance with recommendations issued by pediatric societies and national advisory bodies. The present article reviews the epidemiology of RSV infection and the short- and long-term impact of disease in high-risk infants and special populations. Prevention strategies and treatment are discussed based on the existing scientific evidence, and future challenges in the management of RSV infection are addressed.

The multicenter Italian birth cohort study on incidence and determinants of lower respiratory tract infection hospitalization in infants at 33 weeks GA or more: preliminary results

BACKGROUND

Respiratory syncytial virus (RSV) causes respiratory infections during the first year of life. Very premature infants have more severe diseases and also 'late preterm infants' may be more susceptible to the infection.

AIM OF THE STUDY

To evaluate in an Italian cohort the incidence and risk factors of severe hospitalized lower respiratory tract infection (LRTI) induced or not by RSV during the first year of life.

METHODS

A cohort of 33(+0d)-34(+6d) wGA newborns paired with two sex- and age-matched 35(+0d)-37(+6d) wGA and ≥ 38(+0d) wGA newborns were enrolled. Hospitalization for LRTI induced or not by RSV during the first year of life was assessed through phone interview at the end of the RSV season (November-March) and at the completion of the first year of life. The parents were asked to report hospitalization for any reason.

RESULTS

1064 neonates were enrolled (November 2009-October 2010), 697 had at least one phone follow-up by September 2010. Babies of 33(+0d)-34(+6d) wGA were more frequently conceived through assisted fertilization technologies, born from cesarean delivery had more frequently acute perinatal risk factors and were more frequently twins. After a mean 6 month-follow-up, we registered 29 hospitalizations for LRTI induced or not by RSV. Hospitalizations were slightly and non-significantly more frequent in 33(+0d)-37(+6d) wGA infants. The risk of hospitalization was significantly 60% reduced in breastfed babies and four folds significantly increased during the RSV season.

CONCLUSION

The very preliminary data of this ongoing study suggest that in 'late-preterm' infants some individual/environmental characteristics of the infants play a relevant role in determining the risk of severe RSV infection.

Environmental Modifiers of Chronic Lung Disease of Prematurity During Infancy

Chronic lung disease is a common complication of prematurity with substantial mortality and morbidity. Although the variation seen in bronchopulmonary dysplasia has a strong genetic component, the limited environmental variation in neonatal intensive care units may lead to underestimates of the contribution of environmental factors to lung disease variation. Once discharged from the hospital, preterm infants are exposed to a variety of environmental factors that likely worsen their disease. Recognition of these factors may lead to improved outcomes in this vulnerable population through more effective guidelines and counseling. This review examines the role of selected outpatient environmental factors on respiratory outcomes during infancy in preterm infants with lung disease.

Pattern recognition receptors and genetic risk for rsv infection: value for clinical decision-making?

Respiratory syncytial virus (RSV) causes respiratory tract infections, especially among young infants. Practically, all infants are infected during epidemics and the clinical presentation ranges from subclinical to fatal infection. Known risk factors for severe RSV infection include prematurity, age of <2 months, underlying chronic lung or heart diseases, serious neurological or metabolic disorders, immune deficiency (especially a disorder of cellular immunity), crowded living conditions, and indoor smoke pollution. Twin studies indicate that host genetic factors affect susceptibility to severe RSV infection. Pattern recognition receptors (PRRs) are the key mediators of the innate immune response to RSV. In the distal respiratory tract, RSV is recognized by the transmembrane Toll-like receptor 4 (TLR4) and adapter proteins, which lead to production of proinflammatory cytokines and subsequent activation of the adaptive immune response. Surfactant proteins A and D are able to bind both RSV and TLR4, modulating the inflammatory response. Genetic variations in TLR4, SP-A, and SP-D have been associated with the risk of severe RSV bronchiolitis, but the results have varied between studies. Both the homozygous hyporesponsive 299Gly genotype of TLR4 and the non-synonymous SP-A and SP-D polymorphism influence the presentation of RSV infection. The reported relative risks associated with these markers are not robust enough to justify clinical use. However, current evidence indicates that innate immune responses including pattern recognition receptors (PRRs) and other components in the distal airways and airspaces profoundly influence the innate immune responses, playing a key role in host resistance to RSV in young infants. This information is useful in guiding efforts to develop better means to identify the high-risk infants and to treat this potentially fatal infection effectively.

Prevention of serious respiratory syncytial virus-related illness. I: Disease pathogenesis and early attempts at prevention

Respiratory syncytial virus (RSV) was first described 160 years ago but was not officially recognized as a cause of serious illness in children until the late 1950s. It has been estimated that virtually all children have had at least one RSV infection by their second birthday. RSV is responsible for annual disease outbreaks, usually during a defined winter seasonal period that can vary by community and year. RSV is recognized as the leading cause of hospitalization among young children worldwide. Infants of young chronologic age and children with predisposing factors, such as premature birth, pulmonary disease, or congenital heart disease, are most susceptible to serious illness. Unlike other viruses, immunity to RSV infection is incomplete and short lived, and reinfection is common throughout life. Initial attempts to develop a vaccine in the 1960s met with unexpected and tragic results; many children vaccinated with a formalin-inactivated wild-type virus developed serious pulmonary disease upon subsequent natural infection. Numerous other vaccine technologies have since been studied, including vectored approaches, virus-like particles, DNA vaccines, and live attenuated virus vaccine. As of early 2010, only two companies or institutions had RSV vaccine candidates in early clinical trials, and no vaccine is likely to be licensed for marketing in the immediate future.

Clinical prediction rule for RSV bronchiolitis in healthy newborns: prognostic birth cohort study

OBJECTIVE

Our goal was to determine predictors of respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) among healthy newborns.

METHODS

In this prospective birth cohort study, 298 healthy term newborns born in 2 large hospitals in the Netherlands were monitored throughout the first year of life. Parents kept daily logs and collected nose/throat swabs during respiratory tract infections. The primary outcome was RSV LRTI, which was defined on the basis of the combination of positive RSV polymerase chain reaction results and acute wheeze or moderate/severe cough.

RESULTS

Of the 298 children, 42 (14%) developed RSV LRTI. Independent predictors for RSV LRTI were day care attendance and/or siblings, high parental education level, birth weight of >4 kg, and birth in April to September. The area under the receiver operating characteristic curve was 0.72 (95% confidence interval: 0.64-0.80). We derived a clinical prediction rule; possible scores ranged from 0 to 5 points. The absolute risk of RSV LRTI was 3% for children with scores of ≤2 (20% of all children) and 32% for children with all 4 factors (scores of 5; 8% of all children). Furthermore, 62% of the children with RSV LRTI experienced wheezing during the first year of life, compared with 36% of the children without RSV LRTI.

CONCLUSIONS

A simple clinical prediction rule identifies healthy newborns at risk of RSV LRTI. Physicians can differentiate between children with high and low risks of RSV LRTI and subsequently can target preventive and monitoring strategies toward children at high risk.

Glucocorticoids for acute viral bronchiolitis in infants and young children

BACKGROUND

Previous systematic reviews have not shown clear benefit of glucocorticoids for acute viral bronchiolitis, but their use remains considerable. Recent large trials add substantially to current evidence and suggest novel glucocorticoid-including treatment approaches.

OBJECTIVES

To review the efficacy and safety of systemic and inhaled glucocorticoids in children with acute viral bronchiolitis.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library 2009, issue 4); MEDLINE (1950 to November 2009); EMBASE (1980 to Week 47 2009); LILACS (1982 to November 2009); Scopus® (1823 to November 2009); and IRAN MedEx (1998 to November 2009).

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing short-term systemic or inhaled glucocorticoids versus placebo or another intervention in children < 24 months with acute bronchiolitis (first episode with wheezing). Our primary outcomes were: admissions by days 1 and 7 for outpatient studies; and length of stay (LOS) for inpatient studies. Secondary outcomes included clinical severity parameters, healthcare use, pulmonary function, symptoms, quality of life and harms.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data on study and participant characteristics, interventions and outcomes. We assessed risk of bias and graded strength of evidence. Inpatient and outpatient results were meta-analysed separately using random-effects models. We pre-specified subgroup analyses, including the combined use of protocolised bronchodilators.

MAIN RESULTS

We included 17 trials (2596 participants); only two had low overall risk of bias. Baseline severity, glucocorticoid schemes, comparators and outcomes were heterogeneous. Glucocorticoids did not significantly reduce outpatient admissions by days 1 and 7 when compared to placebo (pooled risk ratios (RRs) 0.92; 95% CI 0.78 to 1.08; and 0.86; 95% CI 0.7 to 1.06, respectively). There was no benefit in LOS for inpatients (mean difference -0.18 days; 95% CI -0.39 to 0.04). Unadjusted results from a large factorial low risk of bias RCT found combined high-dose systemic dexamethasone and inhaled epinephrine reduced admissions by day 7 (baseline risk of admission 26%; RR 0.65, 95% CI 0.44 to 0.95; number needed to treat 11, 95% CI 7 to 76), with no differences in short-term adverse effects. No other comparisons showed relevant differences in primary outcomes.

AUTHORS' CONCLUSIONS

Current evidence does not support a clinically relevant effect of systemic or inhaled glucocorticoids on admissions or length of hospitalization. Combined dexamethasone and epinephrine may reduce outpatient admissions, but results are exploratory and safety data limited. Future research should further assess the efficacy, harms and applicability of combined therapy.

Real-time detection of influenza a, influenza B, and respiratory syncytial virus a and B in respiratory specimens by use of nanoparticle probes

Seasonal epidemics of influenza and respiratory syncytial virus are responsible for significant morbidity and mortality worldwide. Infrequently, novel or reemergent strains of influenza A virus have caused rapid, severe global pandemics resulting in millions of fatalities. The ability to efficiently and accurately detect and differentiate respiratory viruses is paramount for effective treatment, infection control, and epidemiological surveillance. We evaluated the ability of two FDA-cleared nucleic acid-based tests, the semiautomated respiratory virus nucleic acid test (VRNAT) and the fully automated respiratory virus nucleic acid test SP (RVNAT(SP)) (Nanosphere Inc., Northbrook, IL) to detect influenza A virus, influenza B virus, and respiratory syncytial virus A and B (RSV A/B) from clinical nasopharyngeal swab specimens. Detection of viral RNA in both tests is based on nucleic acid amplification followed by hybridization to capture probes immobilized on a glass slide. A novel technology utilizing gold nanoparticle-conjugated probes is utilized to detect the presence of captured target DNA. This microarray-based approach to detection has proven to be more sensitive than the traditional culture/direct fluorescent-antibody assay (DFA) method for detecting RSV and influenza viruses in clinical specimens, including the novel 2009 H1N1 strain. Specifically, we report 98.0% sensitivity and 96.5% specificity for the VRNAT compared to culture/DFA. Further, the VRNAT detected virus in an additional 58% of specimens that were culture negative. These data were confirmed using bidirectional sequencing. Evaluation of the fully automated RVNAT(SP), which is built on the same detection technology as the VRNAT but contains an updated processor enabling complete automation, revealed the two tests to be functionally equivalent. Thus, the RVNAT(SP) is a fully automated sample-to-result test capable of reliable detection of select respiratory viruses directly from clinical specimens in 3.5 h.

Association of higher adiposity and wheezing in infants with lower respiratory illnesses

AIM

The incidences of asthma and obesity have been steadily increasing over the past two decades, with several studies showing a relationship between these conditions. We investigated the influence of higher weight for height (WFH) Z-score on wheezing in infants with lower respiratory tract infections (LRTI).

METHODS

We reviewed the medical charts of all infants younger than l year of age who were admitted with the first episode of LRTI between 2000 and 2008. Subjects were classified into six groups according to WFH Z-score.

RESULTS

Wheezing was more frequent in infants with higher WFH Z-scores. Especially, wheezing infants aged 3-6 months and 6-9 months had significantly higher WFH Z-scores than had their non-wheezing counterparts (p = 0.05 and p < 0.01 respectively). Multivariate logistic regression showed that age (OR = 0.76, p < 0.001), male gender (OR = 1.61, p = 0.005) and WFH Z-score (OR = 1.12, p = 0.007) were independently associated with wheezing.

CONCLUSION

  In this study we could show that a higher WFH Z-score was independently associated with wheezing in infancy. Attainment of appropriate weight for age may reduce the risk of wheezing in infants with respiratory diseases.