Population-based Influenza and Respiratory Syncytial Virus Hospitalizations and In-hospital Mortality Rates Among Mexican Children Less Than Five Years of Age

BACKGROUND

Population-based information regarding the impact of respiratory syncytial virus (RSV) and influenza on hospital admissions and mortality is scant for many countries.

METHODS

Prospective testing of RSV and influenza virus was undertaken in patients <5 years old admitted to hospital with acute respiratory infection (ARI) between July, 2014 and June, 2015, and mortality rates for children living in 3 municipalities in the state of San Luis Potosí were calculated.

RESULTS

During the 12-month study period, 790 children living in these municipalities were admitted with ARI. RSV was detected in 245 (31%) and influenza in 47 (5.9%). History of preterm birth was recorded for 112 children on admission. For children <5 years old, ARI-, RSV- and influenza-associated admission rates were 23.2, 7.2 and 1.4 (per 1000 population), respectively. The corresponding admission rates per 1000 infants <1 year old were 78, 25.2 and 4.4. Preterm infant admission rates were 2 times higher than those of term infants. Six children died; RSV was detected in 4 (66.6%) of the deceased, while no deaths were associated with influenza. ARI and RSV in-hospital mortality rates for children <5 years were 0.18 and 0.12 per 1000 population. ARI and RSV mortality rates in preterm infants were 7 and 14 times higher than in term infants, respectively.

CONCLUSIONS

RSV was associated with both high admission and in-hospital mortality rates in children <5 years old. Specific interventions, such as active or passive immunization, to prevent RSV infections are required to reduce ARI-associated infant mortality.

Infection of respiratory syncytial viruses (RSV) in the Czech Republic - analysis of hospitalizations and deaths in 2017-2022

OBJECTIVES

Given the lack of data on the seriousness of respiratory syncytial virus (RSV) infections in the Czech Republic, an analysis was made of available data on hospitalizations and the hospitalization risk was estimated by age group.

METHODS

Data from the National Registry of Reimbursed Health Services and the National Registry of Hospitalizations were used for the analyses. Hospitalizations and deaths due to RSV infection (diagnoses J12.1, J20.5, J21.0) from 2017-2022 were analyzed by age group.

RESULTS

Over the six-year period, there were 6,138 hospitalizations with the above diagnoses, ranging between years from 307 to 2,162. The estimated overall hospitalization risk per 100,000 population and year for diagnoses J12.1, J20.5, and J21.0 was 9.64, varying between 2.87 (2020) and 20.56 (2021). Age-group analysis showed the highest risk for children under 6 months of age (891.6/100,000 population and year) and the lowest for 20-34-year-olds (0.1/100,000 population and year). Children under 1 year of age accounted for 63.1% of hospitalizations with the above diagnoses. For patients 65 years and older, the annual hospitalization rates varied between 3.3-15.3%. The most frequent cause of RSV-associated hospitalizations was bronchitis, diagnosed in 55.4% of patients. Among those hospitalized with diagnoses J12.1, J20.5, and J21.0, 38 deaths were reported, representing a case fatality rate of 0.62%. The highest case fatality rate (6.5%) was observed in the age group 35-49 years.

CONCLUSIONS

RSV-associated hospitalizations have been reported in all age groups in the Czech Republic. The highest RSV-associated hospitalization risk in 2017-2022 was estimated among children under 6 months of age. Passive surveillance using the available registries could currently provide the basis for measures specifically tailored to the youngest age categories. Data on the hospitalization of adults, particularly senior citizens, must be improved and complemented with active surveillance.

Respiratory Syncytial Virus-attributable Deaths in a Major Pediatric Hospital in New South Wales, Australia, 1998-2018

BACKGROUND

Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infection and an important contributor to child mortality. In this study, we estimated the frequency and described the clinical features of RSV-attributable deaths in Australian children.

METHODS

We conducted a retrospective observational study of RSV-associated deaths in hospitalized children <16 years of age over a 21-year period (1998-2018) in a pediatric tertiary/quaternary referral hospital in New South Wales (NSW), Australia. RSV-associated deaths were identified, reviewed, and classified according to RSV contribution to death. For 'RSV-attributable' deaths, we estimated frequency, case fatality ratio (CFR), and population death rate. We described demographic and clinical features of cases.

RESULTS

There were 20 RSV-attributable deaths. RSV was considered the primary cause of death for five cases and a contributory cause for 15 cases. The CFR among hospitalized cases was 0.2% (20/9779). The annual death rate was 0.6 per 10,000 hospitalized children. The population death rate was 1.2 (95% confidence interval 0.5-2.7) per million children <16 years of age in NSW. The median age at death was 28.7 months (interquartile range 8.8-75.0). All children had at least one medical comorbidity. Over half the deaths occurred in children ≥2 years of age (11, 55%). RSV healthcare-associated infection (RSV-HAI) was common (11, 55%).

CONCLUSIONS

RSV-attributable death is infrequent in this setting. Deaths occurred exclusively in children with medical comorbidity and a high proportion were RSV-HAI. Children with medical comorbidity, including those ≥2 years of age, should be prioritized for targeted prevention of RSV disease.

Infant deaths from respiratory syncytial virus in Lusaka, Zambia from the ZPRIME study: a 3-year, systematic, post-mortem surveillance project

Background

Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infections and a key driver of childhood mortality. Previous RSV burden of disease estimates used hospital-based surveillance data and modelled, rather than directly measured, community deaths. Given this uncertainty, we conducted a 3-year post-mortem prevalence study among young infants at a busy morgue in Lusaka, Zambia—the Zambia Pertussis RSV Infant Mortality Estimation (ZPRIME) study.

Methods

Infants were eligible for inclusion if they were aged between 4 days and less than 6 months and were enrolled within 48 h of death. Enrolment occurred mainly at the University Teaching Hospital of the University of Zambia Medical School (Lusaka, Zambia), the largest teaching hospital in Zambia. We extracted demographic and clinical data from medical charts and official death certificates, and we conducted verbal autopsies with the guardian or next of kin. RSV was identified using reverse transcriptase quantitative PCR and stratified by age, time of year, and setting (community vs facility deaths). By combining the PCR prevalence data with syndromic presentation, we estimated the proportion of all infant deaths that were due to RSV.

Findings

The ZPRIME study ran from Aug 31, 2017, to Aug 31, 2020, except for from April 1 to May 6, 2020, during which data were not collected due to restrictions on human research at this time (linked to COVID-19). We enrolled 2286 deceased infants, representing 79% of total infant deaths in Lusaka. RSV was detected in 162 (7%) of 2286 deceased infants. RSV was detected in 102 (9%) of 1176 community deaths, compared with 10 (4%) of 236 early facility deaths (<48 h from admission) and 36 (5%) of 737 late facility deaths (≥48 h from admission). RSV deaths were concentrated in infants younger than 3 months (116 [72%] of 162 infants), and were clustered in the first half of each year and in the poorest and most densely populated Lusaka townships. RSV caused at least 2·8% (95% CI 1·0–4·6) of all infant deaths and 4·7% (1·3–8·1) of community deaths.

Interpretation

RSV was a major seasonal cause of overall infant mortality, particularly among infants younger than 3 months of age. Because most RSV deaths occurred in the community and would have been missed through hospital-based surveillance, the global burden of fatal RSV has probably been underestimated.

Funding

Bill & Melinda Gates Foundation.

Viral burden and diversity in acute respiratory tract infections in hospitalized children in wet and dry zones of Sri Lanka

The present study was done to identify the viral diversity, seasonality and burden associated with childhood acute respiratory tract infection (ARTI) in Sri Lanka. Nasopharyngeal aspirates (NPA) of hospitalized children (1 month-5 years) with ARTI were collected in 2 centers (wet and dry zones) from March 2013 to August 2014. Respiratory viral antigen detection by immunofluorescence assay (IFA) was used to identify the infecting viruses. IFA negative 100 NPA samples were tested for human metapeumovirus (hMPV), human bocavirus and corona viruses by polymerase chain reaction. Of the 443 and 418 NPAs, 37.2% and 39.4% were positive for any of the 8 different respiratory viruses tested from two centers studied. Viral co-infection was detected with respiratory syncytial virus (RSV) in both centers. Peak viral detection was noted in the wet zone from May-July 2013 and 2014 and in the dry zone from December-January 2014 suggesting a local seasonality for viral ARTI. RSV showed a clear seasonality with a direct correlation of monthly RSV infections with rainy days in the wet zone and an inverse correlation with temperature in both centers. The case fatality rate was 2.7% for RSV associated ARTI. The overall disability adjusted life years was 335.9 and for RSV associated ARTI it was 241.8. RSV was the commonly detected respiratory virus with an annual seasonality and distribution in rainy seasons in the dry and wet zones of Sri Lanka. Identifying the virus and seasonality will contribute to employ preventive measures and reduce the empirical use of antibiotics in resource limited settings.

Exacerbation of Influenza A Virus Disease Severity by Respiratory Syncytial Virus Co-Infection in a Mouse Model

Influenza A virus (IAV) and respiratory syncytial virus (RSV) are leading causes of childhood infections. RSV and influenza are competitive in vitro. In this study, the in vivo effects of RSV and IAV co-infection were investigated. Mice were intranasally inoculated with RSV, with IAV, or with both viruses (RSV+IAV and IAV+RSV) administered sequentially, 24 h apart. On days 3 and 7 post-infection, lung tissues were processed for viral loads and immune cell populations. Lung functions were also evaluated. Mortality was observed only in the IAV+RSV group (50% of mice did not survive beyond 7 days). On day 3, the viral loads in single-infected and co-infected mice were not significantly different. However, on day 7, the IAV titer was much higher in the IAV+RSV group, and the RSV viral load was reduced. CD4 T cells were reduced in all groups on day 7 except in single-infected mice. CD8 T cells were higher in all experimental groups except the RSV-alone group. Increased airway resistance and reduced thoracic compliance were demonstrated in both co-infected groups. This model indicates that, among all the infection types we studied, infection with IAV followed by RSV is associated with the highest IAV viral loads and the most morbidity and mortality.

Clinical outcomes of adults hospitalized for laboratory confirmed respiratory syncytial virus or influenza virus infection

Objectives

Respiratory syncytial virus (RSV) can cause severe disease in adults, but far less is known than for influenza. The aim of our study was to compare the disease course of RSV infections with influenza infections among hospitalized adults.

Methods

We retrieved clinical data from an ongoing surveillance of adults hospitalized with RSV or influenza virus infection in two acute care hospitals in North-Eastern Switzerland during the winter seasons 2017/2018 and 2018/2019. Our main analysis compared the odds between RSV and influenza patients for admission to an intensive care unit (ICU) or in-hospital death within 7 days after admission.

Results

There were 548 patients, of whom 79 (14.4%) had an RSV and 469 (85.6%) an influenza virus infection. Both groups were similar with respect to age, sex, smoking status, nutritional state, and comorbidities. More RSV patients had an infiltrate on chest radiograph on admission (46.4% vs 29.9%, p = .007). The proportion of patients with RSV who died or were admitted to ICU within seven days after admission was 19.0% compared to 10.2% in influenza patients (p = .024). In multivariable analysis, a higher leukocyte count (adjusted OR 1.07, 95% CI 1.02–1.13, p = .013) and the presence of a pneumonic infiltrate (aOR 3.41, 95% CI 1.93–6.02) significantly increased the risk for experiencing the adverse primary outcome while the effect of the underlying viral pathogen became attenuated (aOR 1.18, 95% CI 0.58–2.41, p = .0.655).

Conclusions

Our results suggest that RSV is responsible for clinical courses at least as severe as influenza in adults. This supports the need for better guidance on diagnostic strategies as well as on preventive and therapeutic measures for hospitalized adults with RSV infection.

Surveillance of respiratory syncytial virus infections in adults, Austria, 2017 to 2019

Respiratory syncytial virus (RSV) testing is generally available in most care centres, but it is rarely performed because clinicians' seldom suspect RSV to be the underlying pathogen in adults with respiratory disease. Here, we evaluate the impact of broad combined influenza/RSV testing on the clinical practice. Overall, 103 patients were tested positively for RSV. Our study indicates that positively tested patients were mostly of advanced age and suffered from chronic diseases. Mortality was significant in our cohort and higher in patients with advanced age. Further, we report a significant increase in detected RSV cases but also in detection rate. Together, these findings suggest that implementation of a combined influenza/RSV testing led to a significant increase in detection rate, supported clinicians establishing the correct diagnosis and allowed a safe and controlled handling of RSV patients.

Estimated Burden of Community-Onset Respiratory Syncytial Virus-Associated Hospitalizations Among Children Aged <2 Years in the United States, 2014-15

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of hospitalizations in young children. We estimated the burden of community-onset RSV-associated hospitalizations among US children aged <2 years by extrapolating rates of RSV-confirmed hospitalizations in 4 surveillance states and using probabilistic multipliers to adjust for ascertainment biases.

METHODS

From October 2014 through April 2015, clinician-ordered RSV tests identified laboratory-confirmed RSV hospitalizations among children aged <2 years at 4 influenza hospitalization surveillance network sites. Surveillance populations were used to estimate age-specific rates of RSV-associated hospitalization, after adjusting for detection probabilities. We extrapolated these rates using US census data.

RESULTS

We identified 1554 RSV-associated hospitalizations in children aged <2 years. Of these, 27% were admitted to an intensive care unit, 6% needed mechanical ventilation, and 5 died. Most cases (1047/1554; 67%) had no underlying condition. Adjusted age-specific RSV hospitalization rates per 100 000 population were 1970 (95% confidence interval [CI],1787 to 2177), 897 (95% CI, 761 to 1073), 531 (95% CI, 459 to 624), and 358 (95% CI, 317 to 405) for ages 0-2, 3-5, 6-11, and 12-23 months, respectively. Extrapolating to the US population, an estimated 49 509-59 867 community-onset RSV-associated hospitalizations among children aged <2 years occurred during the 2014-2015 season.

CONCLUSIONS

Our findings highlight the importance of RSV as a cause of hospitalization, especially among children aged <2 months. Our approach to estimating RSV-related hospitalizations could be used to provide a US baseline for assessing the impact of future interventions.

Palivizumab and prevention of childhood respiratory syncytial viral infection: protocol for a systematic review and meta-analysis of breakthrough infections

INTRODUCTION

Childhood respiratory syncytial virus (RSV) infection is a global phenomenon that can lead to fatal respiratory illness. Palivizumab is a drug that is routinely used in affluent countries as a prophylaxis against RSV infection; nevertheless, breakthrough infections are often reported. In light of new findings on potential RSV resistance to palivizumab, an up-to-date synthesis of evidence on effectiveness is needed. Furthering existing reviews, a broadened scope to better reflect effectiveness in a 'real world' clinical context is also important. This systematic review and meta-analysis will enhance our understanding of the effectiveness of palivizumab in varying populations of children. Findings from this review will inform recommendations for best practices regarding palivizumab use for childhood RSV infection as well as research priorities in RSV vaccine development.

METHODS AND ANALYSIS

We will conduct a systematic review of primary population-based studies that examine the incidence of palivizumab breakthrough infections in children, published between 1997 to present. In collaboration with a research librarian, four electronic databases (MEDLINE, Embase, Cochrane Library, Web of Science) and additional sources will be searched. Study screening and quality assessment will be performed in duplicate. Data will be extracted by one reviewer, with partial and random verification by a second reviewer. The primary outcomes to assess breakthrough RSV infection will be hospitalisation, length of stay and the need for intensive care unit admission and mechanical ventilation in children receiving palivizumab. The secondary outcome will be RSV-associated mortality. We will conduct a meta-analysis using pooled effectiveness data, and include subgroup analyses by patient comorbidities and drug compliance. Sensitivity analyses for risk of bias and study design will also be performed.

ETHICS AND DISSEMINATION

This systematic review will only include data from previously published literature and is therefore exempt from ethics approval. Final results will be disseminated through peer-reviewed publication and presented at academic conferences and scientific meetings engaging paediatric researchers and healthcare providers. Should findings from this review necessitate updates to current clinical practice guidelines, we intend to establish a working group to engage relevant health administrators and decision makers.

PROSPERO REGISTRATION NUMBER

CRD42019122120.

In- and Out-of-hospital Mortality Associated with Seasonal and Pandemic Influenza and Respiratory Syncytial Virus in South Africa, 2009-2013

Background

Estimates of influenza- and respiratory syncytial virus (RSV)-associated mortality burden are important to guide policy for control. Data are limited on the contribution of out-of-hospital deaths to this mortality.

Methods

We modeled excess mortality attributable to influenza and RSV infection by applying regression models to weekly deaths from national vital statistics from 2009 through 2013, using influenza and RSV laboratory surveillance data as covariates. We fitted separate models for in- and out-of-hospital deaths.

Results

There were 509791 average annual deaths in South Africa, of which 44% (95% confidence interval [CI] 43%-45%) occurred out-of-hospital. Seasonal influenza and RSV all-cause mortality rates were 23.0 (95% CI 11.0-30.6) and 13.2 (95% CI 6.4-33.8) per 100000 population annually (2.3% [95%CI 2.3%-2.4%] and 1.3% [95% CI 1.2%-1.4%] of all deaths respectively). The peak mortality rate was in individuals aged ≥75 years (386.0; 95% CI 176.5-466.3) for influenza and in infants (143.4; 95% CI 0-194.8) for RSV. Overall, 63% (95% CI 62%--65%) of seasonal influenza and 48% (95% CI 47%-49%) of RSV-associated deaths occurred out-of-hospital. Among children aged <5 years, RSV-associated deaths were more likely to occur in-hospital, whereas influenza-associated deaths were more likely to occur out-of-hospital. The mortality rate was 6.7 (95% CI 6.4-33.8) in the first influenza A(H1N1)pdm09 wave in 2009 and 20.9 (95% CI 6.4-33.8) in the second wave in 2011, with 30% (95% CI 29%-32%) of A(H1N1)pdm09-associated deaths in 2009 occurring out-of-hospital.

Discussion

More than 45% of seasonal influenza- and RSV-associated deaths occur out-of-hospital in South Africa. These data suggest that hospital-based studies may substantially underestimate mortality burden.

Supplemental Oxygen-Free Days in Hematopoietic Cell Transplant Recipients With Respiratory Syncytial Virus

Background

Clinically meaningful endpoints for respiratory syncytial virus (RSV) treatment trials are lacking for hematopoietic cell transplant (HCT) recipients. We evaluated supplemental oxygen use among HCT recipients with RSV infection.

Methods

Subjects were grouped according to the presence of upper respiratory tract infection (URTI) without lower respiratory tract infection (LRTI), URTI progressing to LRTI, and LRTI at presentation. LRTI was defined as a positive lower respiratory tract sample with or without radiographic abnormality (defined as proven or probable LRTI, respectively) or a positive upper respiratory tract sample with radiographic abnormality (possible LRTI). Supplemental oxygen–free days were defined as any day while alive after diagnosis of RSV infection during which ≤2 L of supplemental oxygen per minute was received.

Results

Among 230 patients, supplemental oxygen use by day 28 after the first diagnosis of RSV infection was lowest in patients presenting with URTI (31 of 197 [16%]). Supplemental oxygen use was lower in patients with possible LRTI (12 of 45 [27%]) than in those with proven/probable LRTI (29 of 42 [69%]). Patients presenting with proven/probable LRTI had a median of 16 fewer supplemental oxygen–free days than those presenting with URTI (P < .0001). Death only occurred among patients with proven/probable LRTI (11 of 42 [26%]).

Conclusions

Confirmation of RSV infection in the lower respiratory tract provides prognostic information that may help prioritize therapies. Supplemental oxygen–free days as a clinical endpoint may allow smaller sample sizes for trials evaluating RSV antivirals.

The epidemiology of medically attended respiratory syncytial virus in older adults in the United States: A systematic review

Objective

This review was undertaken to assess the historical evidence of the disease incidence and burden of laboratory-confirmed respiratory syncytial virus (RSV) in medically attended older adults.

Design

A qualitative systematic literature review was performed; no statistical synthesis of the data was planned, in anticipation of expected heterogeneity across studies in this population.

Methods

A literature search of PubMed, Embase, and the Cochrane Library was conducted for studies of medically attended RSV in older adults (≥ 50 years) published in the last 15 years. Two independent reviewers screened titles and abstracts based on predefined inclusion and exclusion criteria.

Results

From 10 studies reporting incidence proportions, RSV may be the causative agent in up to 12% of medically attended acute respiratory illness in older adults unselected for comorbidities, with variations in clinical setting and by year. In multiple studies, medically attended–RSV incidence among older adults not selected for having underlying health conditions increased with increasing age. Of prospectively followed lung transplant recipients, 16% tested positive for RSV. In hospitalized adults with chronic cardiopulmonary diseases, 8% to 13% were infected with RSV during winter seasons (8%-13%) or metapneumovirus season (8%). Hospitalizations for RSV in older adults typically lasted 3 to 6 days, with substantial proportions requiring intensive care unit admission and mechanical ventilation. Among older adults hospitalized with RSV, the mortality rate was 6% to 8%.

Conclusions

Protection of older adults against RSV could reduce respiratory-related burden, especially as age increases and the prevalence of comorbidities (especially cardiopulmonary comorbidities) grows.

Estimating influenza and respiratory syncytial virus-associated mortality in Western Kenya using health and demographic surveillance system data, 2007-2013

Background

Influenza and respiratory syncytial virus (RSV) associated mortality has not been well-established in tropical Africa.

Methods

We used the negative binomial regression method and the rate-difference method (i.e. deaths during low and high influenza/RSV activity months), to estimate excess mortality attributable to influenza and RSV using verbal autopsy data collected through a health and demographic surveillance system in Western Kenya, 2007–2013. Excess mortality rates were calculated for a) all-cause mortality, b) respiratory deaths (including pneumonia), c) HIV-related deaths, and d) pulmonary tuberculosis (TB) related deaths.

Results

Using the negative binomial regression method, the mean annual all-cause excess mortality rate associated with influenza and RSV was 14.1 (95% confidence interval [CI] 0.0–93.3) and 17.1 (95% CI 0.0–111.5) per 100,000 person-years (PY) respectively; and 10.5 (95% CI 0.0–28.5) and 7.3 (95% CI 0.0–27.3) per 100,000 PY for respiratory deaths, respectively. Highest mortality rates associated with influenza were among ≥50 years, particularly among persons with TB (41.6[95% CI 0.0–122.7]); and with RSV were among <5 years. Using the rate-difference method, the excess mortality rate for influenza and RSV was 44.8 (95% CI 36.8–54.4) and 19.7 (95% CI 14.7–26.5) per 100,000 PY, respectively, for all-cause deaths; and 9.6 (95% CI 6.3–14.7) and 6.6 (95% CI 3.9–11.0) per 100,000 PY, respectively, for respiratory deaths.

Conclusions

Our study shows a substantial excess mortality associated with influenza and RSV in Western Kenya, especially among children <5 years and older persons with TB, supporting recommendations for influenza vaccination and efforts to develop RSV vaccines.

Lower Respiratory Tract Diseases Caused by Common Respiratory Viruses among Stem Cell Transplantation Recipients: A Single Center Experience in Korea

PURPOSE

To describe the incidence, clinical courses, and risk factors for mortality of lower respiratory tract diseases (LRDs) caused by common respiratory viruses (CRVs) in stem cell transplantation (SCT) recipients.

MATERIALS AND METHODS

We retrospectively reviewed the medical records of 1038 patients who received SCT between January 2007 and August 2011 at a single center in Korea.

RESULTS

Seventy-one CRV-LRDs were identified in 67 (6.5%) patients. The human parainfluenza virus (HPIV) was the most common causative pathogen of CRV-LRDs at 100 days [cumulative incidence estimate, 23.5%; 95% confidence interval (CI), 3.3-43.7] and 1 year (cumulative incidence estimate, 69.2%; 95% CI, 45.9-92.5) following SCT. The 30-day overall mortality rates due to influenza-LRDs, respiratory syncytial virus-LRDs, HPIV-LRDs, and human rhinovirus-LRDs were 35.7, 25.8, 31.6, and 42.8%, respectively. Co-pathogens in respiratory specimens were detected in 23 (33.8%) patients. The overall mortality at day 30 after CRV-LRD diagnosis was 32.8% (22/67). High-dose steroid usage (p=0.025), a severe state of immunodeficiency (p=0.033), and lymphopenia (p=0.006) were significantly associated with death within 30 days following CRV-LRD diagnosis in a univariate analysis. Multivariate logistic regression analysis revealed that high-dose steroid usage [odds ratio (OR), 4.05; 95% CI, 1.12-14.61; p=0.033] and lymphopenia (OR, 6.57; 95% CI, 1.80-24.03; p=0.004) were independent risk factors for mortality within 30 days of CRV-LRDs.

CONCLUSION

CRV-LRDs among SCT recipients showed substantially high morbidity and mortality rates. Therefore, the implement of an active diagnostic approaches for CRV infections is required for SCT recipients with respiratory symptoms, especially those receiving high-dose steroids or with lymphopenia.

Child pneumonia - focus on the Western Pacific Region

Worldwide, pneumonia is the leading cause of death in infants and young children (aged <5 years). We provide an overview of the global pneumonia disease burden, as well as the aetiology and management practices in different parts of the world, with a specific focus on the WHO Western Pacific Region. In 2011, the Western Pacific region had an estimated 0.11 pneumonia episodes per child-year with 61,900 pneumonia-related deaths in children less than 5 years of age. The majority (>75%) of pneumonia deaths occurred in six countries; Cambodia, China, Laos, Papua New Guinea, the Philippines and Viet Nam. Historically Streptococcus pneumoniae and Haemophilus influenzae were the commonest causes of severe pneumonia and pneumonia-related deaths in young children, but this is changing with the introduction of highly effective conjugate vaccines and socio-economic development. The relative contribution of viruses and atypical bacteria appear to be increasing and traditional case management approaches may require revision to accommodate increased uptake of conjugated vaccines in the Western Pacific region. Careful consideration should be given to risk reduction strategies, enhanced vaccination coverage, improved management of hypoxaemia and antibiotic stewardship.

Deaths associated with respiratory syncytial and influenza viruses among persons ≥5 years of age in HIV-prevalent area, South Africa, 1998-2009(1)

We estimated deaths attributable to influenza and respiratory syncytial virus (RSV) among persons >5 years of age in South Africa during 1998-2009 by applying regression models to monthly deaths and laboratory surveillance data. Rates were expressed per 100,000 person-years. The mean annual number of seasonal influenza-associated deaths was 9,093 (rate 21.6). Persons >65 years of age and HIV-positive persons accounted for 50% (n = 4,552) and 28% (n = 2,564) of overall seasonal influenza-associated deaths, respectively. In 2009, we estimated 4,113 (rate 9.2) influenza A(H1N1)pdm09-associated deaths. The mean of annual RSV-associated deaths during the study period was 511 (rate 1.2); no RSV-associated deaths were estimated in persons >45 years of age. Our findings support the recommendation for influenza vaccination of older persons and HIV-positive persons. Surveillance for RSV should be strengthened to clarify the public health implications and severity of illness associated with RSV infection in South Africa.

Detection of Multiple Respiratory Viruses Associated With Mortality and Severity of Illness in Children

OBJECTIVE

Respiratory viral infection is a common source of morbidity and mortality in children. Coinfection with multiple viruses occurs frequently; however, the clinical significance of concomitant viral pathogens is unclear. We hypothesized that presence of more than one respiratory virus is associated with increased morbidity and mortality when compared with children with a single respiratory virus.

DESIGN

Retrospective cohort study.

SETTING

A tertiary care hospital.

PATIENTS

All children at Duke Children's Hospital over a 2-year period with isolation of a virus on an extended viral respiratory panel result. Demographic data, comorbidities, and details of hospital encounter were recorded.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Two hundred thirty-five hospital encounters demonstrated positive extended viral respiratory panels. Immunocompromised status (37%) and respiratory comorbidities (23%) were common. Twenty-eight patients (12%) tested positive for multiple viruses, with adenovirus (23/28) and respiratory syncytial virus (15/28) most prevalent in patients with multiple viruses. Viral codetection was associated with increased use of noninvasive ventilation (p = 0.02), extracorporeal membrane oxygenation (p = 0.02), increased likelihood of moderate or severe illness (p = 0.005), and increased mortality (p = 0.01). Subgroup analysis demonstrated that this mortality association persisted for children with normal immune function (p = 0.003) and children with no comorbidities (p = 0.007).

CONCLUSIONS

Children with multiple respiratory viruses may be at increased risk of moderate or severe illness and mortality, with previously healthy children potentially being at greatest risk. Further studies are indicated to determine the significance and generalizability of this finding and to better understand the pathophysiology of viral coinfection.

Respiratory Syncytial Virus Bronchiolitis in Children up to 5 Years of Age in Spain: Epidemiology and Comorbidities: An Observational Study

This epidemiological survey in Spain estimates the burden of respiratory syncytial virus (RSV) infection in children up to 5 year of age during a 15-year period (1997-2011). Observational retrospective survey was conducted by reviewing data of the National Surveillance System for Hospital Data, including >98% of Spanish hospitals. All hospitalizations related to RSV infection for children up to 5 years, reported during 1997-2011 period, were analyzed. Codes were selected by using the International Classification of Diseases 9th Clinical Modification 466.0-466.19, 480.1, and 079.6. A total of 326,175 and 286,007 hospital discharges for children up to 5 and 2 years of age were reported during the study period. The annual incidence was 1072 and 2413 patients per 100,000, respectively. The average length of hospital stay was 5.7 (standard deviation 8.2) days. Four hundred forty-six deaths were reported; of those, 403 occurred in children <2 years and 355 (80%) occurred in children <12 months of age. Hospitalization and mortality rates were significantly higher in boys and decrease significantly with age. The higher rate of hospitalization and mortality rates were found in the first year of life. Annual average cost for National Health Care System was € 47 M with a mean hospitalization cost of €2162. The average length of hospitalization and costs were significantly higher in high-risk children. RSV infections in children up to 5 year of age still pose a significant health threat in Spain, especially in the infants. The development of preventive, diagnostic, and therapeutic guidelines focused in children with comorbidities may help reduce the hospital and economic burden of the disease.

Mechanical ventilation drives inflammation in severe viral bronchiolitis

Introduction

Respiratory insufficiency due to severe respiratory syncytial virus (RSV) infection is the most frequent cause of paediatric intensive care unit admission in infants during the winter season. Previous studies have shown increased levels of inflammatory mediators in airways of mechanically ventilated children compared to spontaneous breathing children with viral bronchiolitis. In this prospective observational multi-center study we aimed to investigate whether this increase was related to disease severity or caused by mechanical ventilation.

Materials and Methods

Nasopharyngeal aspirates were collected <1 hour before intubation and 24 hours later in RSV bronchiolitis patients with respiratory failure (n = 18) and non-ventilated RSV bronchiolitis controls (n = 18). Concentrations of the following cytokines were measured: interleukin (IL)-1α, IL-1β, IL-6, monocyte chemotactic protein (MCP)-1 and macrophage inflammatory protein (MIP)-1α.

Results

Baseline cytokine levels were comparable between ventilated and non-ventilated infants. After 24 hours of mechanical ventilation mean cytokine levels, except for MIP-1α, were elevated compared to non-ventilated infected controls: IL-1α (159 versus 4 pg/ml, p<0.01), IL-1β (1068 versus 99 pg/ml, p<0.01), IL-6 (2343 versus 958 pg/ml, p<0.05) and MCP-1 (174 versus 26 pg/ml, p<0.05).

Conclusions

Using pre- and post-intubation observations, this study suggests that endotracheal intubation and subsequent mechanical ventilation cause a robust pulmonary inflammation in infants with RSV bronchiolitis.

Viral respiratory burden in moderate-to-late preterm infants

More than 1 in 10 babies are born prematurely and most of them are born after gestational age 32 weeks. Mortality and morbidity are more common in these moderate-to-late preterm infants than in full-term children. In this review, mechanisms and epidemiology of long-term airway morbidity in moderate-to-late preterm infants will be discussed. We discuss the potential of viral respiratory infections to further aggravate abnormal lung function associated with preterm birth.

Mortality rates of human metapneumovirus and respiratory syncytial virus lower respiratory tract infections in hematopoietic cell transplantation recipients

Human metapneumovirus (HMPV), a common respiratory virus, can cause severe disease in pre- and post-hematopoietic cell transplantation (HCT) recipients. We conducted a retrospective cohort analysis in HCT patients with HMPV (n = 23) or respiratory syncytial virus (n = 23) detected in bronchoalveolar lavage samples by reverse transcription PCR between 2006 and 2011 to determine disease characteristics and factors associated with outcome. Mortality rates at 100 days were 43% for both HMPV and respiratory syncytial virus lower respiratory tract disease. Steroid therapy, oxygen requirement >2 L or mechanical ventilation, and bone marrow as cell source were significant risk factors for overall and virus-related mortality in multivariable models, whereas the virus type was not. The presence of centrilobular/nodular radiographic infiltrates was a possible protective factor for mechanical ventilation. Thus, HMPV lower respiratory tract disease is associated with high mortality in HCT recipients. Earlier detection in combination with new antiviral therapy is needed to reduce mortality among HCT recipients.

Challenges to evaluating respiratory syncytial virus mortality in Bangladesh, 2004-2008

Background

Acute lower respiratory illness is the most common cause of death among children, globally. Data are not available to make accurate estimates on the global mortality from respiratory syncytial virus (RSV), specifically.

Methods

Respiratory samples collected from children under 5 years of age during 2004 to 2008 as part of population-based respiratory disease surveillance in an urban community in Dhaka, Bangladesh were tested for RSV, human metapneumovirus (HMPV), human parainfluenza virus (PIV) types 1, 2, and 3, influenza and adenovirus by RT-PCR. Verbal autopsy data were used to identify children who died from respiratory illness in a nearby rural community. Significance of the correlation between detections and community respiratory deaths was determined using Spearman's coefficient.

Results

RSV activity occurred during defined periods lasting approximately three months but with no clear seasonal pattern. There was no significant correlation between respiratory deaths and detection of any of the respiratory viruses studied.

Conclusion

Outbreaks of respiratory viruses may not be associated with deaths in children in the study site; however, the few respiratory deaths observed and community-to-community variation in the timing of outbreaks may have obscured an association. An accurate assessment of respiratory virus-associated deaths will require detections and death data to come from the same location and a larger study population.

Mortality and morbidity of nosocomial respiratory syncytial virus (RSV) infection in ventilated children--a ten year perspective

BACKGROUND

Respiratory syncytial virus (RSV) is one of the most common pathogens involved in nosocomial infection in children. The aim of the study was to determine the impact of nosocomial RSV infection on mortality and pediatric intensive care unit (PICU) morbidity of ventilated children.

METHODS

This is a prospective observational cohort study of all children ventilated with RSV infection in a tertiary-referral PICU over a 10-year period. Determinants of the relationship of nosocomial (PICU-acquired and hospital ward-acquired) RSV infection to mortality and PICU morbidity were adjusted for by performing multiple regression analysis.

RESULTS

Of 525 RSV-positive children ventilated on PICU during the ten-year study period, 38 (7.2%) acquired their RSV infection following PICU admission and 38 (7.2%) had acquired RSV in hospital. Ten (26%) children that acquired RSV on PICU died (RR 6.4, 95%CI 3.2-12.9) and 11 (29%) with hospital ward-acquired infection died (RR 9.8, 95%CI 5.1-18.9), compared to 18 (4%) with community-acquired RSV infection. Nosocomial RSV infection was significantly and independently associated with death which was more strongly predicted by immunodeficiency and congenital heart disease (P<0.01). Nosocomial RSV infection was the strongest predictor for morbidity as reflected in duration of ventilation and length of stay on PICU (P<0.01).

CONCLUSION

Nosocomial RSV infection was independently associated with increased mortality and was the strongest predictor of duration of ventilation and length of stay in children on PICU. Decreasing nosocomial RSV infection would reduce deaths in ventilated children.

Part 4. Interaction between air pollution and respiratory viruses: time-series study of daily mortality and hospital admissions in Hong Kong

BACKGROUND

Populations in Asia are not only at risk of harm to their health through environmental degradation as a result of worsening pollution problems but also constantly threatened by recurring and emerging influenza epidemics and. pandemics. Situated in the area with the world's fastest growing economy and close to hypothetical epicenters of influenza transmission, Hong Kong offers a special opportunity for testing environmental management and public health surveillance in the region. In the Public Health and Air Pollution in Asia (PAPA*) project, the Hong Kong research team assessed the health effects of air pollution and influenza as well as the interaction between them. The team also assessed disparities in the health effects of air pollution between relatively deprived and more affluent areas in Hong Kong. The aim was to provide answers to outstanding research questions relating to the short-term effects of air pollution on mortality and hospital admissions; the health effects of influenza with a view to validating different measures of influenza activity according to virologic data; the confounding effects of influenza on estimates of the health effects of air pollution; the modifying effects of influenza on the health effects of air pollution; and the modifying effects of neighborhood social deprivation on the health effects of air pollution.

DATA

Data on mortality and hospital admissions for all natural causes, as well as the subcategories of cardiovascular diseases (CVD) and respiratory diseases (RD), were derived from the Hong Kong Census and Statistics Department and the Hospital Authority. Daily concentrations of nitrogen dioxide (NO2), sulfur dioxide (SO2), particulate matter with an aerodynamic diameter < or = 10 pm (PM10); and ozone (O3) were derived from eight monitoring stations with hourly data that were at least 75% complete during the study period. Three measures of influenza and respiratory syncytial virus (RSV) activity were derived from positive isolates of specimens in the virology laboratory of Queen Mary Hospital (QMH), the main clinical teaching center at The University of Hong Kong and part of the Hong Kong Hospital Authority network of teaching hospitals: influenza intensity (defined as the weekly proportion of positive isolates of influenza in the total number of specimens received for diagnostic tests); the presence of influenza epidemic (defined as a period when the weekly frequency of these positive isolates is > or = 4% of the annual total number of positive isolates [i.e., twice the expected mean value] in two or more consecutive weeks); and influenza predominance (defined as a period of influenza epidemic when the weekly frequency of RSV was less than 2% for two or more consecutive weeks). The weekly proportion of positive isolates of RSV in total specimens was determined in the same way as for influenza intensity. A social deprivation index (SDI) was defined by taking the average of the proportions of households or persons with the following six characteristics in each geographic area using the census statistics: unemployment; household income < U.S. $250 per month; no schooling at all; never-married status; one-person household; and subtenancy. A Poisson regression with quasi-likelihood to account for overdispersion was used to develop core models for daily health outcomes, with a natural spline smoothing function to filter out seasonal patterns and long-term trends in this time-series study of daily mortality and hospital admissions, and with adjustment for days of the week, temperature, and relative humidity (RH). Air pollutant concentration values were entered into the core model to assess the health effects of specific pollutants. The possible confounding effects of influenza were assessed by observing changes in magnitude of the effect estimate when each influenza measurement was entered into the model; and interactions between air pollution and influenza were assessed by entering the terms for the product of the air pollutant concentration and a measurement of influenza activity into the model. A Poisson regression analysis was performed to assess the effects of air pollution in each area belonging to low, middle, or high social deprivation strata according to the tertiles of the SDI. The differences in air pollution effects were tested by a case-only approach. RESULTS The excess risk (ER) estimates for the short-term effects of air pollution on mortality and hospitalization for broad categories of disease were greater in those 65 years and older than in the all-ages group and were consistent with other studies. The biggest health impacts were seen at the extremes of the age range. The three measures employed for influenza activity based on virologic data-one based on a proportion and the other two using frequencies of positive influenza isolates-were found to produce consistent health impact estimates, in terms of statistical significance. In general, we found that adjustment for influenza activity in air pollution health effect estimations took account of relatively small confounding effects. However, we conclude that it is worthwhile to make the adjustment in a sensitivity analysis and to obtain the best possible range of effect estimates from the data, especially for respiratory hospitalization. Interestingly, interaction effects were found between influenza activity and air pollution in the estimated risks for hospitalization for RD, particularly for 03. These results could be explained in terms of the detrimental effects of both influenza viruses and air pollutants, which may be synergistic or competing with each other, though the mechanism is still unknown. The results deserve further study and the attention of both public health policy makers and virologists in considering prevention strategies. IMPLICATIONS In Hong Kong, where air pollution may pose more of a health threat than in North American and Western European cities, the effects of air pollution also interact with influenza and with residence in socially deprived areas, potentially leading to additional harm. Asian governments should be aware of the combined risks to the health of the population when considering environmental protection and management in the context of economic, urban, and infrastructure development. This is the first study in Asia to examine the interactions between air pollution, influenza, and social deprivation from an epidemiologic perspective. The biologic mechanisms are still unclear, and further research is needed.

Fatality rates in published reports of RSV hospitalizations among high-risk and otherwise healthy children

OBJECTIVE

To review the fatalities among children hospitalized with respiratory syncytial virus (RSV) infection, and identify factors leading to a fatal outcome.

RESEARCH DESIGN AND METHODS

Review of literature identified from a structured search of PubMed (1966-2009) using the following Medical Subject Headings: respiratory syncytial virus infection; hospitalized; infants; and risk factors. Publications were restricted to: English language; full papers; inclusion of > or =10 subjects; children aged < or =18 years, hospitalization for RSV infection; and deaths reported. Case fatality rates were defined as number of deaths divided by number of children hospitalized for RSV and were calculated for each study.

RESULTS

Thirty-six studies met the inclusion and exclusion criteria. Case fatality rates among children hospitalized for RSV ranged from 0 to 33%. In general, studies showed that subgroups of high-risk children (chronic lung disease [CLD] 3.5-23%, congenital heart disease [CHD] 2-37%, and prematurity 0-6.1%) had higher fatality rates than older or otherwise healthy children (consistently <1%). Presence of severe underlying comorbidities such as neuromuscular disease, immunosuppression, and malignancies was associated with death among term and/or older (>1 year) children. Higher fatality rates were reported for infants receiving intensive unit care (1.1-8.6%), extracorporeal life support (33%) or for those who acquired nosocomial RSV infection (0-12.2%). The majority of studies did not report cause of death and clinical details of the fatal cases were often not provided. Other limitations of this review include our search limits, the possibility of inherent bias in our methodology that could result in an under or over estimation of case-fatality rates, and potential publication bias.

CONCLUSIONS

Children at high risk for RSV (CLD, CHD and prematurity), those with severe underlying comorbidities, or those with nosocomial RSV appear to be at increased risk for death after RSV hospitalization. More data are needed on cause of death and how much is directly attributable to RSV.

Influenza- and respiratory syncytial virus-associated adult mortality in Soweto

BACKGROUND

Influenza and respiratory syncytial virus (RSV) infections cause seasonal excess mortality and hospitalisation in adults (particularly the elderly) in high-income countries. Little information exists on the impact of these infections on adults in Africa.

OBJECTIVES

To estimate influenza- and RSV-related adult mortality, stratified by age and hospitalisation in Soweto.

STUDY DESIGN

A retrospective hospital-based study in Soweto from 1997 to 1999 to estimate influenza- and RSV-related excess all-cause deaths and hospitalisation using a rate-difference method. The study was based on influenza seasons of varying severity, provided by surveillance data.

RESULTS

Influenza seasons were significantly associated with excess mortality in adults across all 3 years, except for 18 - 64-year-olds in 1998. Excess mortality was highest in those > or = 65 years of age: 82.8/100 000 population in the mild 1997 season and 220.9/100 000 in the severe 1998 season. Influenza significantly increased adult medical hospitalisation in the severe 1998 season alone. RSV did not significantly affect mortality or hospitalisation.

CONCLUSION

Influenza-related mortality was substantial and disproportionately affected the elderly. Influenza vaccination for the elderly warrants consideration. The RSV-related burden was not significantly increased but merits observation over a longer period.

A meta-analysis of the effect of antibody therapy for the prevention of severe respiratory syncytial virus infection

BACKGROUND

The primary objective of this meta-analytic study was to determine the impact of RSV-IGIV and palivizumab on risk of respiratory syncytial virus (RSV)-related hospitalization. Secondary objectives were to determine if antibody therapy decreases the risk of RSV infection, intensive care admission, mechanical ventilation, and mortality in high risk infant populations.

METHODS

We performed searches of electronic data bases from 1966 to April 2009. Inclusion and exclusion criteria were defined a priori. Inclusion criteria were as follows: 1) There was randomization between polyclonal or monoclonal antibodies and placebo or no therapy, and 2) Polyclonal or monoclonal antibodies were given as prophylaxis.

RESULTS

Of the six included studies, three utilized RSV-IGIV (total of 533 randomized to treatment groups) and three utilized palivizumab (total of 1,663 randomized to treatment groups). The absolute risk of hospitalization in the control arms was 12% and overall RR for all 2,196 children who received one of the antibody products was 0.53 (95% CI 0.43, 0.66), P < 0.00001. When looking only at the children who received palivizumab, the RR for hospitalization was 0.50 (95% CI 0.38, 0.66), P < 0.00001. For the children receiving RSV-IGIV, the RR for hospitalization was 0.59 (95% CI 0.42, 0.83, P < 0.002). The use of palivizumab resulted in a significant decrease in admission to the ICU (RR 0.29 (95% CI 0.14, 0.59; P = 0.0007). There was no significant reduction in the risk of mechanical ventilation or mortality with the use of antibody prophylaxis. Infants born at less than 35 weeks gestational age, and those with chronic lung and congenital heart disease all had a significant reduction in the risk of RSV hospitalization with children born under 35 weeks gestational age showing a trend towards the greatest benefit.

CONCLUSION

Both palivizumab and RSV-IGIV decrease the incidence of RSV hospitalization and ICU admission and their effect appears to be qualitatively similarly. There was neither a statistically significant reduction in the incidence of mechanical ventilation nor in all cause mortality. This meta-analysis separately quantifies the impact of RSV-IGIV and palivizumab on various measures of severe RSV disease and builds upon a previous study that was only able to examine the pooled effect of all antibody products together.

[Severe bronchiolitis. Epidemiology and clinical course of 284 patients]

INTRODUCTION

Bronchiolitis is the leading cause of hospital admission and a frequent cause of pediatric intensive care unit (PICU) admission among infants during the winter months. The objective of this study was to analyze the characteristics and clinical course of patients admitted to the PICU for bronchiolitis.

PATIENTS AND METHOD

We performed a descriptive, observational study by clinical chart review of all patients admitted to the PICU for severe bronchiolitis from November 1994 to March 2006.

RESULTS

A total of 284 patients were included. Most were admitted during December and January and 74% had respiratory syncytial virus (RSV) infection. At least one risk factor for severe disease was present in 68% of the patients: the most frequent risk factor was age < 6 weeks (45%), followed by prematurity (30%). Mechanical ventilation was required in 64 of the 284 patients (24%). Mortality was 1.8% and was associated with chronic pre-existing illness (p < 0.001). The factors associated with a greater risk of mechanical ventilation and a longer PICU stay were the association of two or more risk factors (42/284; 15%), the presence of apnea (73/284; 25.7%), and images of pulmonary consolidation or atelectasis on admission chest X-ray (157/284; 55%).

CONCLUSIONS

Most patients admitted for severe bronchiolitis to the PICU are healthy infants whose principal risk factor is young age. The main predictors of severe clinical course during PICU stay are the association of two or more risk factors, the presence of apnea, and pulmonary consolidation on admission chest X-ray. Bronchiolitis-associated mortality is low and is associated with pre-existing chronic illness.

Influenza- and respiratory syncytial virus-associated mortality and hospitalisations

The aim of the current study was to estimate influenza- and respiratory syncytial virus (RSV)-associated mortality and hospitalisations, especially the influenza-associated burden among low-risk individuals < or =65 yrs old, not yet recommended for influenza vaccination in many European countries. Retrospectively during 1997-2003, Dutch national all-cause mortality and hospital discharge figures and virus surveillance data were used to estimate annual average influenza- and RSV-associated excess mortality and hospitalisation using rate difference methods. Influenza virus active periods were significantly associated with excess mortality among 50-64-yr-olds and the elderly, but not in younger age categories. Influenza-associated hospitalisation was highest and about equal for 0-1-yr-olds and the elderly, and also significant for low-risk adults. Hospitalisation among children was mostly due to respiratory conditions, and among adults cardiovascular complications were frequent. RSV-active periods were associated with excess mortality and hospitalisation among the elderly. The highest RSV-related excess hospitalisation was found in 0-1-yr-olds. Influenza-associated mortality was demonstrated in 50-64-yr-olds. Among low-risk individuals < or =65 yrs of age, influenza-associated hospitalisation rates were highest for 0-4-yr-olds, but also significant for 5-64-yr-olds. These data may further support extension of recommendations for influenza vaccination to include younger low-risk persons. The respiratory syncytial virus-associated burden was highest for young children but also substantial for the elderly.

Hospitalized children with respiratory syncytial virus infection and neuromuscular impairment face an increased risk of a complicated course

BACKGROUND

Respiratory syncytial virus (RSV) infection is an important cause of viral respiratory tract infection in children. In contrast to other confirmed risk factors that predispose to a higher morbidity and mortality, the particular risk of a preexisting neuromuscular impairment (NMI) in hospitalized children with RSV infection has not been prospectively studied in a multicenter trial.

METHODS

The DMS RSV Paed database was designed for the prospective multicenter documentation and analysis of all clinically relevant aspects of the management of inpatients with RSV infection. Patients with clinically relevant NMI were identified according to the specific comments of the attending physicians and compared with those without NMI.

RESULTS

This study covers 6 consecutive seasons; the surveillance took place in 14 pediatric hospitals in Germany from 1999 to 2005. In total, 1568 RSV infections were prospectively documented in 1541 pediatric patients. Of these, 73 (4.7%) patients displayed a clinically relevant NMI; 41 (56%) NMI patients had at least 1 additional risk factor for a severe course of the infection (multiple risk factors in some patients; prematurity in 30, congenital heart disease in 19, chronic lung disease 6 and immunodeficiency in 8). Median age at diagnosis was higher in NMI patients (14 vs. 5 months); NMI patients had a greater risk of seizures (15.1% vs. 1.6%), and a higher proportion in the NMI group had to be mechanically ventilated (9.6% vs. 1.9%). Eventually, the attributable mortality was significantly higher in the NMI group (5.5% vs. 0.2%; P < 0.001 for all). Multivariate logistic regression confirmed that NMI was independently associated with pediatric intensive care unit (PICU) admission (OR, 4.94; 95% CI, 2.69-8.94; P < 0.001] and mechanical ventilation (OR, 3.85; 95% CI, 1.28-10.22; P = 0.017).

CONCLUSION

This is the first prospective multicenter study confirming the hypothesis that children with clinically relevant NMI face an increased risk for severe RSV-disease. It seems reasonable to include NMI as a cofactor into the decision algorithm of passive immunization.

Palivizumab prophylaxis to prevent respiratory syncytial virus mortality after pediatric bone marrow transplantation: a decision analysis model

OBJECTIVE

Palivizumab, a monoclonal antibody against respiratory syncytial virus (RSV), has been demonstrated to be safe and effective in young children, but evidence is lacking as to whether palivizumab is effective in preventing RSV-induced morbidity and mortality in children who are immunosuppressed after bone marrow transplantation (BMT). As a randomized, double-blind, placebo-controlled trial is lacking, we chose to examine this issue with the use of decision analysis methodology.

METHODS

A decision tree was designed to determine mortality from RSV-related lung disease in children who received palivizumab after BMT. Probabilities were derived by meta-analysis methodology on the basis of the available literature. Sensitivity analyses were performed across a broad range of biologically plausible probabilities to judge the robustness of the results of the model.

RESULTS

The model revealed that there is a 10% increase in survival in BMT patients who receive palivizumab. The absolute survival rate increased from 83% to 92%. A practitioner would need to treat 12 children to save 1 post-BMT child from dying from RSV-related lung disease.

CONCLUSIONS

Decision analysis modeling demonstrates a decrease in mortality in pediatric BMT patients with the addition of palivizumab to protect against RSV-related lung disease. A well-designed, randomized controlled trial is necessary.

Molecular investigations of an outbreak of parainfluenza virus type 3 and respiratory syncytial virus infections in a hematology unit

A large simultaneous outbreak of respiratory syncytial virus (RSV) and parainfluenza type 3 (PIV-3) infections occurred on an adult hematology unit. Implementation of enhanced infection control was complicated by cocirculation of the two different viruses, with prolonged viral shedding from infected patients, and placed great pressure on health care staff; of 27 infected hematopoietic stem cell transplant patients, 9 died, and the unit was closed for 2 months. Retrospective molecular investigation of the virus strains involved in the outbreak was performed by analyzing part of the fusion gene of PIV-3 and part of the glycoprotein gene of RSV. Reverse transcription-PCR on nasopharyngeal aspirates from patients infected before and during the simultaneous outbreak generated amplicons for sequence analysis. A single strain of RSV and a single strain of PIV-3 had spread from person to person within the unit; 7 patients were infected with RSV, 22 were infected with PIV-3, and 4 were infected with both viruses. The PIV-3 outbreak had started at the beginning of August 3 months before the RSV outbreak; it had arisen when PIV-3 was introduced from the community by a patient and passed to another patient, who became chronically infected with the identical strain and, in spite of being nursed in isolation, was most likely the source from which widespread infection occurred in November. Had these early cases been linked to a common PIV-3 strain at the time of diagnosis, enhanced infection control precautions might have prevented the eventual extensive spread of PIV-3, making it much easier to deal with the later RSV outbreak.

The histopathology of fatal untreated human respiratory syncytial virus infection

The pathology of respiratory syncytial virus (RSV) infection was evaluated 1 day after an outpatient diagnosis of RSV in a child who died in a motor vehicle accident. We then identified 11 children with bronchiolitis from the Vanderbilt University autopsy log between 1925 and 1959 who met criteria for possible RSV infection in the preintensivist era. Their tissue was re-embedded and evaluated by routine hematoxylin and eosin and PAS staining and immunostaining with RSV-specific antibodies. Tissue from three cases was immunostain-positive for RSV antigen and was examined in detail. Small bronchiole epithelium was circumferentially infected, but basal cells were spared. Both type 1 and 2 alveolar pneumocytes were also infected. Although, not possible for archival cases, tissue from the index case was evaluated by immunostaining with antibodies to define the cellular components of the inflammatory response. Inflammatory infiltrates were centered on bronchial and pulmonary arterioles and consisted of primarily CD69+ monocytes, CD3+ double-negative T cells, CD8+ T cells, and neutrophils. The neutrophil distribution was predominantly between arterioles and airways, while the mononuclear cell distribution was in both airways and lung parenchyma. Most inflammatory cells were concentrated submuscular to the airway, but many cells traversed the smooth muscle into the airway epithelium and lumen. Airway obstruction was a prominent feature in all cases attributed to epithelial and inflammatory cell debris mixed with fibrin, mucus, and edema, and compounded by compression from hyperplastic lymphoid follicles. These findings inform our understanding of RSV pathogenesis and may facilitate the development of new approaches for prevention and treatment.

Respiratory viral infections in adults with hematologic malignancies and human stem cell transplantation recipients: a retrospective study at a major cancer center

Community respiratory viruses (CRVs) have been recognized as a potential cause of pneumonia and death among hematopoietic stem cell transplantation (HSCT) recipients and patients with hematologic malignancies. We reviewed the Microbiology Laboratory records dated from July 1, 2000, to June 30, 2002, to identify patients who had respiratory specimens positive for influenza, parainfluenza, respiratory syncytial virus, or picornavirus. We identified 343 infections among patients with underlying hematologic malignancies and HSCT. We collected data on type of disease, age, sex, type of infection, neutrophil and lymphocyte counts, therapy, and outcome. Influenza, parainfluenza, and respiratory syncytial virus accounted for most cases and were approximately equal in frequency. Most infections occurred predominantly among recipients of allogeneic transplants. Infection progressed to pneumonia in 119 patients (35%) and occurred with similar frequency for the 3 viruses. Patients at greatest risk for developing pneumonia included those with leukemia, those aged more than 65 years, and those with severe neutropenia or lymphopenia. Lack of respiratory syncytial virus-directed antiviral therapy (p=0.025) and age (p=0.042) were associated with development of respiratory syncytial virus pneumonia, and an absolute lymphocyte count<or=200 cells/mL (p=0.049) was associated with development of influenza pneumonia. The overall mortality rate for CRV pneumonia was 15%. The only independent predictor of fatal outcome was an absolute lymphocyte count<or=200 cells/mL (p=0.03) in patients with influenza pneumonia.HSCT recipients and patients with hematologic malignancies who develop upper respiratory infection due to CRVs should be considered for antiviral therapy of proven efficacy to reduce the risk of pneumonia and death.

Clinical course of hospitalised children infected with human metapneumovirus and respiratory syncytial virus

AIM

To describe the clinical presentation and outcomes of hospitalised patients infected with human metapneumovirus (hMPV) and human respiratory syncytial virus (hRSV) in a tertiary hospital in Cape Town, South Africa.

METHODS

hMPV was identified in 17 respiratory specimens submitted for viral studies during the period 2001-2003. These patients' medical folders were retrospectively reviewed for clinical, radiological and laboratory data, together with a convenience sample of 20 hRSV-infected patients.

RESULTS

hMPV-infected patients were older than those infected with hRSV (P = 0.04) and required a longer hospital stay (P = 0.02). Presenting clinical signs and symptoms were similar between groups. Fourteen (87.5%) hMPV- and 16 (80%) hRSV-infected patients presented with co-morbid and/or immunosuppressive conditions (P > or = 0.5). The most common abnormalities on chest radiographs in both groups were bronchial wall thickening, focal consolidation and atelectasis. Six (37.5%) hMPV- and 11 (55%) hRSV-infected patients required admission to the paediatric intensive care unit (P > 0.1) with five (31.3%) hMPV- and eight (40%) hRSV-infected patients requiring intubation and ventilation (P > 0.5). Three (18.7%) hMPV-patients and three (15%) hRSV-infected patients died during this admission (P > 0.5). All hMPV-infected patients who died had significant co-morbid conditions.

CONCLUSIONS

These data confirm that hMPV is a significant respiratory pathogen in this setting, with similar presentation and outcome to hRSV infection. This is the largest report of hMPV infection causing significant morbidity, prolonged hospital stay and death, associated with underlying risk factors.

Respiratory syncytial virus infections in congenital heart defects--hospitalizations and costs

AIMS

To register hospitalizations for respiratory syncytial virus (RSV) infections and estimate costs of prophylaxis with humanized monoclonal antibodies (palivizumab) against RSV, compared to hospital care, in cases with congenital heart defects (CHDs).

METHODS

Population based study with prospective registration of CHDs. Costs for hospital treatment of RSV-infections in CHD-patients calculated by means of the Norwegian Diagnosis Related Groups system.

RESULTS

In 43 470 infants live born in the population through the 18-year period 1987-2004 a structural CHD was diagnosed in 527 (1.2%). A total of 898 (2.1%) hospitalizations for RSV-infections occurred in the study population 1987-2005. The hospital admittance rate was significantly higher for CHD-cases (4.8%) than for children without CHD (2%) (P = 0.002). Severe CHDs (need for surgery or catheter intervention) had a higher admittance rate (9.2%) compared to the group of remaining CHDs (3.3%) (P = 0.01). Number needed to treat with palivizumab to avoid one hospitalization for RSV-infection in cases of severe CHDs was calculated to 24, at costs of US dollar 195,000. The expenses for palivizuamab prophylaxis in severe CHDs were 31 times that of hospital treatment.

CONCLUSION

Prophylaxis with palivizumab in severe CHDs is not cost-effective.

Mortality in children from influenza and respiratory syncytial virus

STUDY OBJECTIVE

To quantify mortality attributable to influenza and respiratory syncytial virus (RSV) infection in children.

DESIGN AND METHODS

Comparison of death rates (all cause and certified respiratory) in England over winters 1989/90 to 1999/00 during and outside influenza and RSV circulation periods. Virus active weeks were defined from clinical and virological surveillance data. Excess deaths associated with weeks of either influenza or RSV activity over virus non-active weeks were estimated in each winter for age groups 1-12 months, 1-4, 5-9, and 10-14 years. The estimate obtained was allotted to influenza and RSV in the proportion derived from independent separate calculations for each virus.

MAIN RESULTS

Average winter respiratory deaths attributed to influenza in children 1 month-14 years were 22 and to RSV 28; and all cause deaths to influenza 78 and to RSV 79. All cause RSV attributed deaths in infants 1-12 months exceeded those for influenza every year except 1989/90; the average RSV and influenza attributed death rates were 8.4 and 6.7 per 100 000 population respectively. Corresponding rates for children 1-4 years were 0.9 and 0.8 and for older children all rates were 0.2 or less, except for an influenza rate of 0.4 in children 10-14 years.

CONCLUSIONS

Influenza and RSV account for similar numbers of deaths in children. The impact varies by winter and between age groups and is considerably underestimated if analysis is restricted to respiratory certified deaths. Summing the impact over the 11 winters studied, compared with influenza RSV is associated with more deaths in infants less than 12 months, almost equal numbers in children 1-4 years, and fewer in older children. Improved information systems are needed to investigate paediatric deaths.

Prospective study of healthcare utilisation and respiratory morbidity due to RSV infection in prematurely born infants

BACKGROUND

A study was undertaken to determine the impact of respiratory syncytial virus (RSV) infection, both in hospital and the community, on healthcare utilisation and respiratory morbidity in prematurely born infants and to identify risk factors for symptomatic RSV infection.

METHODS

A hospital and community follow up study was undertaken of 126 infants born before 32 weeks of gestational age. Healthcare utilisation (hospital admissions and general practitioner attendances) in the first year, respiratory morbidity at follow up (wheeze and cough documented by parent completed diary cards), and RSV positive lower respiratory tract infections (LRTIs) were documented. Nasopharyngeal aspirates were obtained for immunofluorescence and culture for RSV whenever the infants had an LRTI, either in the community or in hospital.

RESULTS

Forty two infants had an RSV positive LRTI (RSV group), 50 had an RSV negative LRTI (RSV negative LRTI group), and 32 infants had no LRTI (no LRTI group). Compared with the RSV negative LRTI and the no LRTI groups, the RSV group required more admissions (p=0.392, p<0.001) and days in hospital (p=0.049, p=0.006) and had more cough (p=0.05, p=0.038) and wheeze (p=0.003, p=0.003) at follow up. Significant risk factors for symptomatic RSV LRTI were number of siblings (p=0.035) and maternal smoking in pregnancy (p=0.005), for cough were number of siblings (p=0.002) and RSV LRTI (p=0.02), and for wheeze was RSV LRTI (p=0.019).

CONCLUSION

RSV infection, even if hospital admission is not required, is associated with increased subsequent respiratory morbidity in prematurely born infants.

The immune response to viral lower respiratory tract infection

Viruses are responsible for the majority of respiratory infections in childhood,causing considerable morbidity and mortality. It is estimated that in the United States approximately $ 652 million per year is spent on medical costs for respiratory syncytial virus (RSV) related disease alone (Paramore et al., 2004). Viruses cause a variety of respiratory diseases in children from the common cold to life-threatening pneumonia and bronchiolitis. The host reacts to a viral infection with a combination of innate and adaptive immune mechanisms, usually resulting in the clearance of the virus and clinical recovery. However, there is an accumulating evidence for a number of viral infections that the host immune response actually enhances disease in the course of clearing virus from the infected organs. Interestingly, the effectiveness of the immune response seems to be dependent on the age and probably genetic background of the child. This has important implications for treatment as well as vaccine development.