Survey of severe respiratory syncytial virus infection in Kyoto Prefecture from 2003 to 2007

Disease burden of respiratory syncytial virus infection in the pediatric population in Japan

INTRODUCTION

Respiratory syncytial virus (RSV) is one of the most common causes of lower respiratory tract infections in children aged <5 years and is associated with long-term respiratory morbidities such as recurrent wheezing and asthma, decreased lung function, and allergic sensitization. The objective of this review was to evaluate the epidemiology and burden of RSV infection in the pediatric population in Japan.

METHODS

Studies indexed in PubMed and ICHUSHI databases during January 2010-December 2020 were manually reviewed. Data on proportion of RSV infections, seasonality, length of stay (LoS), mortality, medical expenses, and palivizumab use were extracted from the selected articles.

RESULTS

Ninety-three articles were included (PubMed, 64; ICHUSHI, 29). The proportion of patients/samples with an RSV infection was 5.5%-66.7%, and 6.0%-29.9% in the inpatient and outpatient departments, respectively. RSV infections generally occurred during autumn/winter; however, recently the peak has shifted to summer. The LoS was variable and depended on factors such as age, infection severity, wheezing, and RSV subgroups. Mortality rates varied from <1% to 19% depending on the infection severity. The average daily hospitalization and intensive care unit cost was JPY 34,548 while intensive care unit incurred an additional cost of JPY 541,293. Palivizumab was indicated for high-risk infants and 0%-3% of patients required hospitalization despite palivizumab use.

CONCLUSIONS

RSV imposes a significant burden on the Japanese healthcare system, suggesting a need to create awareness among caregivers of children, pregnant women and healthcare professionals to ensure early recognition of infection and adequate treatment or prophylaxis.

Increased Platelet-Derived Growth Factor and Cytokine Levels in the Cerebrospinal Fluid of Patients of Sudden Unexpected Death with or without Viral Infection

OBJECTIVE

To clarify the pathogenesis of sudden unexpected natural death (SUD) as well as biomarkers to differentiate the underlying diseases, by performing cytokine analysis in the acute phase of pediatric patients in whom viral infection led to SUD.

METHODS

An acute phase cytokine analysis of pediatric patients in whom viral infection led to SUD was performed, and the data obtained were compared with those from SUD patients not associated with viral infections. Subjects included 4 boys aged 1-16 mo who died of cardiopulmonary arrest associated with viral infections. The causative viruses were identified as enterovirus, parainfluenza virus, respiratory syncytial virus, and rotavirus. The 4 other infants/children (aged 2-12 mo) died of non-infectious episodes, i.e., 1, 2, and 1 died of drowning, falling, and a traffic accident, respectively. Cerebrospinal fluid samples (CSF) of the subjects were collected during cardiopulmonary resuscitation or within 24 h of the events.

RESULTS

The infection-induced sudden death group showed elevated CSF levels of inflammatory cytokines and chemokines. No increase was observed in interleukin-10 levels. Furthermore, in the infection-induced sudden death group, platelet-derived growth factor levels correlated with inflammatory cytokine levels.

CONCLUSIONS

Infection-associated SUD may be differentiated from noninfectious SUD by measuring the levels of acute phase-inflammatory cytokines and chemokines at the onset of SUD.

Bacterial co-infection of the respiratory tract in ventilated children with bronchiolitis; a retrospective cohort study

Background

Viral bronchiolitis is the most common cause of respiratory failure requiring invasive ventilation in young children. Bacterial co-infections may complicate and prolong paediatric intensive care unit (PICU) stay. Data on prevalence, type of pathogens and its association with disease severity are limited though. These data are especially important as bacterial co-infections may be treated using antibiotics and could reduce disease severity and duration of PICU stay. We investigated prevalence of bacterial co-infection and its association with disease severity and PICU stay.

Methods

Retrospective cohort study of the prevalence and type of bacterial co-infections in ventilated children performed in a 14-bed tertiary care PICU in The Netherlands. Children less than 2 years of age admitted between December 2006 and November 2014 with a diagnosis of bronchiolitis and requiring invasive mechanical ventilation were included. Tracheal aspirates (TA) and broncho-alveolar lavages (BAL) were cultured and scored based on the quantity of bacteria colony forming units (CFU) as: co-infection (TA > 10^{^5}/BAL > 10^{^4} CFU), low bacterial growth (TA < 10^{^5}/BAL < 10^{^4} CFU), or negative (no growth). Duration of mechanical ventilation and PICU stay were collected using medical records and compared against the presence of co-infection using univariate and multivariate analysis.

Results

Of 167 included children 63 (37.7%) had a bacterial co-infection and 67 (40.1%) low bacterial growth. Co-infections occurred within 48 h from intubation in 52 out 63 (82.5%) co-infections. H.influenza (40.0%), S.pneumoniae (27.1%), M.catarrhalis (22.4%), and S.aureus (7.1%) were the most common pathogens. PICU stay and mechanical ventilation lasted longer in children with co-infections than children with negative cultures (9.1 vs 7.7 days, p = 0.04 and 8.1vs 6.5 days, p = 0.02).

Conclusions

In this large study, bacterial co-infections occurred in more than a third of children requiring invasive ventilation for bronchiolitis and were associated with longer PICU stay and mechanical ventilation. These findings support a clinical trial of antibiotics to test whether antibiotics can reduce duration of PICU stay.

Immunohistochemical detection of respiratory syncytial virus at autopsy

BACKGROUND

Respiratory syncytial virus (RSV) infection can be fatal in infants <1 year after birth. Morphological findings associated with infant death, however, are insufficient, and screening procedures are problematic. The aim of the present study was to establish a postmortem diagnosis of RSV pathogenicity.

METHODS

Serial forensic autopsies of 55 infants who suddenly died ≤1 year after birth due to viral pneumonia (n = 18), bacterial pneumonia (n = 12), or other diseases and trauma (n = 25) were assessed. Causes of viral pneumonia determined on immunochemical screening and histological staining of airway effusions consisted of RSV (n = 8) and other viruses (n = 10).

RESULTS

Bronchial epithelial and inflammatory cells in the interstitium around bronchioles and alveoli were immunopositive for RSV. Bronchial epithelium was more frequently positive for RSV (5/8, 62.5%) than for bacterial pneumonia and other causes of death (7/47, 14.9%); and intra-alveolar sites were also more frequently positive for RSV pneumonia (3/8, 37.5%) than for bacterial pneumonia and other causes of death (4/47, 8.5%). Screening immunoassays and immunohistochemical staining for RSV can serve as an index of RSV infection when serum antibody titers, viral identification and polymerase chain reaction (PCR) are not informative. Peribronchiolar interstitial RSV positivity was similar between RSV pneumonia (7/8, 87.5%) and other causes of death (34/47, 72.3%).

CONCLUSIONS

RSV was the cause of death in only eight infants because RSV infection was difficult to diagnose. Therefore, more deaths associated with RSV need to be investigated. Bronchial epithelium and intra-alveolar cells that are RSV immunopositive might augment RSV pathogenicity in viral pneumonia.

Clinical characteristics and risk factors of severe respiratory syncytial virus-associated acute lower respiratory tract infections in hospitalized infants

BACKGROUND

To investigate the clinical characteristics and analyze risk factors for severe respiratory syncytial virus (RSV) infection in hospitalized infants with acute lower respiratory tract infections (ALRIs).

METHODS

A retrospective review of the medical records of infants with RSV-associated ALRIs between March 1st, 2011 and February 29th, 2012 was conducted. Subjects were followed up over the phone or by outpatient visit six and twelve months after discharge.

RESULTS

Among 913 RSV-associated ALRIs infants, 288 (31.5%) had severe infections, which accounted for 4.2% of hospitalized children. The hospital RSV mortality rate was 1.0%. The proportions of cases with tachypnea, apnea, cyanosis, and fine rales were significantly higher in the severe ALRIs group (all P<0.001). Multivariate logistic regression showed that low-birth-weight [1.698 (1.028-2.805)], age less than 3 months old [3.385 (2.174-5.271)], congenital heart disease [1.667 (1.149-2.418)], bronchopulmonary dysplasia [8.505 (1.731-41.780)], and airway abnormalities [2.246 (1.008-5.005)] were independent risk factors for severe ALRIs. The incidence of bronchitis, pneumonia and readmission in the severe group was significantly higher than that of the non-severe group during the one-year follow-up (all P<0.001).

CONCLUSIONS

Younger age, low birth weight and underlying disease are associated with severe RSVassociated ALRIs. Furthermore, severe RSV infections may be associated with a higher frequency of subsequent bronchitis, pneumonia and re-hospitalization in the following year.

Epidemiology and risk factors for severe respiratory syncytial virus infections requiring pediatric intensive care admission in Hong Kong children

PURPOSE

Respiratory syncytial virus (RSV) is a common cause of lower respiratory tract infection in young children. However, there are limited data on severe RSV infection requiring pediatric intensive care unit (PICU) admission. This retrospective study described features of RSV-associated PICU admissions in Hong Kong and investigated factors for mortality and duration of PICU stay.

METHODS

Children with laboratory-confirmed RSV infection and admitted to the PICUs of all eight government hospitals in Hong Kong between January 2009 and June 2011 were identified from computerized auditing systems and PICU databases. RSV in respiratory samples was detected by direct immunofluorescence and/or viral culture. The relationships between mortality and PICU duration and demographic and clinical factors were analyzed.

RESULTS

A total of 118 (2.4 %) PICU admissions were identified among 4,912 RSV-positive pediatric cases in all hospitals. Sixty-five (55.6 %) patients were infants. PICU admissions were higher between October and March. Eight (6.8 %) patients died, but only two were infants. RSV-associated mortality was related to prior sick contact, presence of older siblings, neurodevelopmental conditions, chromosomal and genetic diseases, and bacterial co-infections, but none was significant following logistic regression analyses (odds ratio 9.36, 95 % confidence interval 0.91-96.03 for prior sick contact, p = 0.060). Chronic lung disease was the only risk factor for the duration of PICU admission (β = 0.218, p = 0.017).

CONCLUSIONS

The majority of RSV-infected children do not require PICU support. There is winter seasonality for RSV-associated PICU admission in Hong Kong. Prior sick contact is the only risk factor for RSV-associated mortality, whereas the presence of chronic lung disease is associated with longer PICU stay. The current risk-based approach of RSV prophylaxis may not be effective in reducing severe RSV infections.