Characteristic findings of pediatric inpatients with pandemic (H1N1) 2009 virus infection among severe and nonsevere illnesses

Total alkaloids from Alstonia scholaris inhibit influenza a virus replication and lung immunopathology by regulating the innate immune response

BACKGROUND

Alstonia scholaris is a folk medicine used to treat cough, asthma and chronic obstructive pulmonary disease in China. Total alkaloids (TA) from A. scholaris exhibit anti-inflammatory properties in acute respiratory disease, which suggests their possible anti-inflammatory effect on influenza virus infection.

PURPOSE

To assess the clinical use of TA by demonstrating their anti-influenza and anti-inflammatory effects and the possible mechanism underlying the effect of TA on influenza A virus (IAV) infection in vitro and to reveal the inhibitory effect of TA on lung immunopathology caused by IAV infection.

METHODS

Antiviral and anti-inflammatory activities were assessed in Madin-Darby canine kidney (MDCK) and A549 cells and U937-derived macrophages infected with influenza A/PR/8/34 (H1N1) virus. Proinflammatory cytokine levels were measured by real-time quantitative PCR and Bio-Plex assays. The activation of innate immune signaling induced by H1N1 virus in the absence or presence of TA was detected in A549 cells by Western blot. Furthermore, mice were infected intranasally with H1N1 virus and treated with TA (50, 25 and 12.5 mg/kg/d) or oseltamivir (60 mg/kg/d) for 5 days in vivo. The survival rates and body weight were recorded, and the viral titer, proinflammatory cytokine levels, innate immune cell populations and histopathological changes in the lungs were analyzed.

RESULTS

TA significantly inhibited viral replication in A549 cells and U937-derived macrophages and markedly reduced cytokine and chemokine production at the mRNA and protein levels. Furthermore, TA blocked the activation of pattern recognition receptor (PRR)- and IFN-activated signal transduction in A549 cells. Critically, TA also increased the survival rate, reduced the viral titer, suppressed proinflammatory cytokine production and innate immune cell infiltration and improved lung histopathology in a lethal PR8 mouse model.

CONCLUSION

TA exhibits anti-viral and anti-inflammatory effects against IAV infection by interfering with PRR- and IFN-activated signal transduction.

The role of pneumonia and secondary bacterial infection in fatal and serious outcomes of pandemic influenza a(H1N1)pdm09

BACKGROUND

The aim of this study was to estimate the prevalence of pneumonia and secondary bacterial infections during the pandemic of influenza A(H1N1)pdm09.

METHODS

A systematic review was conducted to identify relevant literature in which clinical outcomes of pandemic influenza A(H1N1)pdm09 infection were described. Published studies (between 01/01/2009 and 05/07/2012) describing cases of fatal or hospitalised A(H1N1)pdm09 and including data on bacterial testing or co-infection.

RESULTS

Seventy five studies met the inclusion criteria. Fatal cases with autopsy specimen testing were reported in 11 studies, in which any co-infection was identified in 23% of cases (Streptococcus pneumoniae 29%). Eleven studies reported bacterial co-infection among hospitalised cases of A(H1N1)2009pdm with confirmed pneumonia, with a mean of 19% positive for bacteria (Streptococcus pneumoniae 54%). Of 16 studies of intensive care unit (ICU) patients, bacterial co-infection identified in a mean of 19% of cases (Streptococcus pneumoniae 26%). The mean prevalence of bacterial co-infection was 12% in studies of hospitalised patients not requiring ICU (Streptococcus pneumoniae 33%) and 16% in studies of paediatric patients hospitalised in general or pediatric intensive care unit (PICU) wards (Streptococcus pneumoniae 16%).

CONCLUSION

We found that few studies of the 2009 influenza pandemic reported on bacterial complications and testing. Of studies which did report on this, secondary bacterial infection was identified in almost one in four patients, with Streptococcus pneumoniae the most common bacteria identified. Bacterial complications were associated with serious outcomes such as death and admission to intensive care. Prevention and treatment of bacterial secondary infection should be an integral part of pandemic planning, and improved uptake of routine pneumococcal vaccination in adults with an indication may reduce the impact of a pandemic.

Influenza burden, prevention, and treatment in asthma-A scoping review by the EAACI Influenza in asthma task force

To address uncertainties in the prevention and management of influenza in people with asthma, we performed a scoping review of the published literature on influenza burden; current vaccine recommendations; vaccination coverage; immunogenicity, efficacy, effectiveness, and safety of influenza vaccines; and the benefits of antiviral drugs in people with asthma. We found significant variation in the reported rates of influenza detection in individuals with acute asthma exacerbations making it unclear to what degree influenza causes exacerbations of underlying asthma. The strongest evidence of an association was seen in studies of children. Countries in the European Union currently recommend influenza vaccination of adults with asthma; however, coverage varied between regions. Coverage was lower among children with asthma. Limited data suggest that good seroprotection and seroconversion can be achieved in both children and adults with asthma and that vaccination confers a degree of protection against influenza illness and asthma-related morbidity to children with asthma. There were insufficient data to determine efficacy in adults. Overall, influenza vaccines appeared to be safe for people with asthma. We identify knowledge gaps and make recommendations on future research needs in relation to influenza in patients with asthma.

Possible explanations for why some countries were harder hit by the pandemic influenza virus in 2009 - a global mortality impact modeling study

BACKGROUND

A global pandemic mortality study found prominent regional mortality variations in 2009 for Influenza A(H1N1)pdm09. Our study attempts to identify factors that explain why the pandemic mortality burden was high in some countries and low in others.

METHODS

As a starting point, we identified possible risk factors worth investigating for Influenza A(H1N1)pdm09 mortality through a targeted literature search. We then used a modeling procedure (data simulations and regression models) to identify factors that could explain differences in respiratory mortality due to Influenza A(H1N1)pdm09. We ran sixteen models to produce robust results and draw conclusions. In order to assess the role of each factor in explaining differences in excess pandemic mortality, we calculated the reduction in between country variance, which can be viewed as an effect-size for each factor.

RESULTS

The literature search identified 124 publications and 48 possible risk factors, of which we were able to identify 27 factors with appropriate global datasets. The modelling procedure indicated that age structure (explaining 40% of the mean between country variance), latitude (8%), influenza A and B viruses circulating during the pandemic (3-8%), influenza A and B viruses circulating during the preceding influenza season (2-6%), air pollution (pm10; 4%) and the prevalence of other infections (HIV and TB) (4-6%) were factors that explained differences in mortality around the world. Healthcare expenditure, levels of obesity, the distribution of antivirals, and air travel did not explain global pandemic mortality differences.

CONCLUSIONS

Our study found that countries with a large proportion of young persons had higher pandemic mortality rates in 2009. The co-circulation of influenza viruses during the pandemic and the circulation of influenza viruses during the preceding season were also associated with pandemic mortality rates. We found that real time assessments of 2009 pandemic mortality risk factors (e.g. obesity) probably led to a number of false positive findings.

Pathogenic analysis of the pandemic 2009 H1N1 influenza A viruses in ferrets

The pandemic 2009 H1N1 influenza A virus emerged in humans and caused the first influenza pandemic of the 21st century. Mexican isolates, A/Mexico/4108/2009 (H1N1) (Mex4108) and A/Mexico/InDRE4478/2009 (H1N1) (Mex4487) derived from a mild case and from a cluster of severe cases, showed heterogeneity in virulence in a cynomolgus macaque model. To compare the more pathogenic differences, we generated recombinant viruses and compared their virulence in ferrets. Ferrets infected with recombinant Mex4487 displayed a slightly higher rate of viral replication and severe pneumonia in the early stage of infection. In contrast, prolonged lower virus shedding of recombinant Mex4108 than that of recombinant Mex4487 was detected in throat swabs. Thus, Mex4487 induces severe pneumonia in infected individuals, whereas Mex4108 might have wide-spreading potential with mild disease.

Identification, Management, and Clinical Characteristics of Hospitalized Patients with Influenza-Like Illness during the 2009 H1N1 Influenza Pandemic, Cook County, Illinois

Objective.

To describe the identification, management, and clinical characteristics of hospitalized patients with influenza-like illness (ILI) during the peak period of activity of the 2009 pandemic strain of influenza A virus subtype H1N1 (2009 H1N1).

Design.

Retrospective review of electronic medical records.

Patients and Setting.

Hospitalized patients who presented to the emergency department during the period October 18 through November 14, 2009, at 4 hospitals in Cook County, Illinois, with the capacity to perform real-time reverse-transcriptase polymerase chain reaction testing for influenza.

Methods.

Vital signs and notes recorded within 1 calendar day after emergency department arrival were reviewed for signs and symptoms consistent with ILI. Cases of ILI were classified as recognized by healthcare providers if an influenza test was performed or if influenza was mentioned as a possible diagnosis in the physician notes. Logistic regression was used to determine the patient attributes and symptoms that were associated with ILI recognition and with influenza infection.

Results.

We identified 460 ILI case patients, of whom 412 (90%) had ILI recognized by healthcare providers, 389 (85%) were placed under airborne or droplet isolation precautions, and 243 (53%) were treated with antiviral medication. Of 401 ILI case patients tested for influenza, 91 (23%) had a positive result. Fourteen (3%) ILI case patients and none of the case patients who tested positive for influenza had sore throat in the absence of cough.

Conclusions.

Healthcare providers identified a high proportion of hospitalized ILI case patients. Further improvements in disease detection can be made through the use of advanced electronic health records and efficient diagnostic tests. Future studies should evaluate the inclusion of sore throat in the ILI case definition.

Early therapy with neuraminidase inhibitors for influenza A (H1N1) pdm 2009 infection

BACKGROUND

Neuraminidase inhibitors have been reported to decrease mortality in patients infected with influenza A (H1N1) pdm 2009 (H1N1 pdm09), but it is not clear whether they are effective against H1N1pdm09 in apparently healthy children.

METHODS

The effect of early treatment with neuraminidase inhibitors on 70 otherwise healthy children with possible H1N1 pdm09 (pH1N1pdm09) infection was investigated. The children were simultaneously treated with a neuraminidase inhibitor (oseltamivir or zanamivir) and maoto, a Japanese traditional herbal medicine, which had been reported to be effective against seasonal influenza. Clinical severity was assessed using patient history, namely the worst values for clinical vital signs and laboratory data on admission. After refining these parameters with univariate, decision tree and multiple regression analysis, mean covariance structure equation analysis was used to investigate the association of estimated clinical severity to the selected parameters.

RESULTS

Total path analysis using a Bayesian method indicated that the estimated clinical severity of pH1N1pdm09 was positively associated with maximum body temperature, pulse rate, respiration rate, duration necessary for defervescence, admission duration and log urinary β2-microglobulin/creatinine level, and negatively associated with age and the presence and duration of treatment with the neuraminidase inhibitor in the outpatient clinic.

CONCLUSIONS

This study provides the first clinical evidence that early treatment with neuraminidase inhibitors in outpatient clinic decreased the estimated clinical severity of pH1N1pdm09 in apparently otherwise healthy pediatric inpatients.

Risk factors for need of mechanical ventilation in children with influenza A(H1N1)pdm09

OBJECTIVE

The pandemic caused by influenza A(H1N1)pdm09 virus peaked between July and August of 2009 in southern Brazil, with the highest incidence in children and young adults. In the post-pandemic period, there was an increase in the incidence of cases during the winter months of 2011 and 2012 in Brazil, similar to seasonal influenza virus. Since infections due to pandemic influenza are still occurring, the present study aimed to investigate the risk factors for worse outcome in children.

METHODS

A retrospective cohort study was performed by reviewing the charts of hospitalized patients younger than 14 years with reverse transcription-polymerase chain reaction (RT-PCR) positive for influenza A(H1N1)pdm09 during the first pandemic wave in six Brazilian tertiary centers. Need for mechanical ventilation was defined as the severity of outcome; age, chronic diseases, bacterial and viral co-detection, chest radiograph findings, and use of oseltamivir were possible predictors.

RESULTS

In the present study, 120 patients were included. In a multivariate analysis, chronic diseases (prevalence ratio: 2.613, 95% CI: 1.267-5.386) and viral co-detection (prevalence ratio: 2.43, 95% CI: 1.203-4.905) were statistically associated with worse outcome (p<0.05).

CONCLUSIONS

The presence of chronic diseases as predictors reinforces previous finding. Furthermore, viral co-detection was found to be a risk factor. Further studies are necessary to confirm this association.

A Portable Infection Screening System Designed for Onboard Entry Screening Based on Multi-Parameter Vital Signs

After outbreak of severe acute respiratory syndrome (SARS) in 2003, many international airport quarantines adopted fever-based screening to identify infected individuals using infrared thermography to control global pandemic. Unfortunately, the sensitivity of fever-based screening system did not exceed 70.4% at Narita International Airport. In order to achieve accurate onboard entry screening for highly contagious infectious diseases, the authors developed a portable system designed for onboard entry screening with linear discriminant analysis. Within several tens of seconds, the system automatically discriminates infected individuals from normal subjects using measured heart rate, respiratory rate, as well as facial surface temperature determined by thermography. The size of system is small enough to be placed on airplane tray tables. The authors tested on 68 subjects including 12 influenza patients to evaluate the system. The result showed sensitivity of 91.7% and specificity of 92.9%. The system seems to be promising for onboard infection screening to safeguard public health.

IgG3 deficiency and severity of 2009 pandemic H1N1 influenza

BACKGROUND

The severity of the 2009 pandemic H1N1 influenza (H1N1 pdm 09) in immune deficient children is unknown. The aim of the present study was to investigate this in a case of complete IgG3 deficiency complicated by pneumonia and asthma attack.

METHODS

The clinical parameters of the IgG3 deficiency patient were compared with those of four control patients using 95% confidence intervals. These control patients were selected from 71 patients admitted due to pneumonia or bronchitis caused by H1N1 pdm 09, and were chosen according to age, absence of pretreatment with oseltamivir before admission, presence of a past history of asthma, use of antibiotics, and combination of inhalation of a beta2 agonist and treatment with i.v. methylprednisolone for asthma attack.

RESULTS

The IgG3 deficiency patient had significantly longer duration of admission and period of oseltamivir, with a significantly decreased pulse oxygen saturation and increased maximum serum C-reactive protein, creatine kinase and urinary excretion of β2-microglobulin/creatinine, compared with the controls (P < 0.05).

CONCLUSIONS

Complete IgG3 deficiency is possibly associated with severity of the clinical course of pneumonia and asthma attack in children suffering from H1N1 pdm 09.

Differential pathological and immune responses in newly weaned ferrets are associated with a mild clinical outcome of pandemic 2009 H1N1 infection

Young children are typically considered a high-risk group for disease associated with influenza virus infection. Interestingly, recent clinical reports suggested that young children were the smallest group of cases with severe pandemic 2009 H1N1 (H1N1pdm) influenza virus infection. Here we established a newly weaned ferret model for the investigation of H1N1pdm infection in young age groups compared to adults. We found that young ferrets had a significantly milder fever and less weight loss than adult ferrets, which paralleled the mild clinical symptoms in the younger humans. Although there was no significant difference in viral clearance, disease severity was associated with pulmonary pathology, where newly weaned ferrets had an earlier pathology improvement. We examined the immune responses associated with protection of the young age group during H1N1pdm infection. We found that interferon and regulatory interleukin-10 responses were more robust in the lungs of young ferrets. In contrast, myeloperoxidase and major histocompatibility complex responses were persistently higher in the adult lungs; as well, the numbers of inflammation-prone granulocytes were highly elevated in the adult peripheral blood. Importantly, we observed that H1N1pdm infection triggered formation of lung structures that resembled inducible bronchus-associated lymphoid tissues (iBALTs) in young ferrets which were associated with high levels of homeostatic chemokines CCL19 and CXCL13, but these were not seen in the adult ferrets with severe disease. These results may be extrapolated to a model of the mild disease seen in human children. Furthermore, these mechanistic analyses provide significant new insight into the developing immune system and effective strategies for intervention and vaccination against respiratory viruses.

Comparison of children hospitalized with seasonal versus pandemic influenza A, 2004-2009

BACKGROUND

The extent to which pandemic H1N1 influenza (pH1N1) differed from seasonal influenza remains uncertain.

METHODS

By using active surveillance data collected by the Immunization Monitoring Program, Active at 12 Canadian pediatric hospitals, we compared characteristics of hospitalized children with pH1N1 with those with seasonal influenza A. We compared demographics, underlying health status, ICU admission, and mortality during both pandemic waves versus the 2004/2005 through the 2008/2009 seasons; influenza-related complications and hospitalization duration during pH1N1 wave 1 versus the 2004/2005 through the 2008/2009 seasons; and presenting signs and symptoms during both pH1N1 waves versus the 2006/2007 through the 2008/2009 seasons.

RESULTS

We identified 1265 pH1N1 cases (351 in wave 1, 914 in wave 2) and 1319 seasonal influenza A cases (816 from 2006/2007 through 2008/2009). Median ages were 4.8 (pH1N1) and 1.7 years (seasonal influenza A); P < .0001. Preexisting asthma was overrepresented in pH1N1 relative to seasonal influenza A (13.8% vs 5.5%; adjusted P < .0001). Symptoms more often associated with pH1N1 wave 1 versus seasonal influenza A were cough, headache, and gastrointestinal symptoms (adjusted P < .01 for each symptom). pH1N1 wave 1 cases were more likely to have radiologically confirmed pneumonia (adjusted odds ratio = 2.1; 95% confidence interval = 1.1-3.8) and longer median length of hospital stay (4 vs 3 days; adjusted P = .003) than seasonal influenza A. Proportions of children requiring intensive care and deaths in both pH1N1 waves (14.6% and 0.6%, respectively) were not significantly different from the seasonal influenza A group (12.7% and 0.5%, respectively).

CONCLUSIONS

pH1N1 in children differed from seasonal influenza A in risk factors, clinical presentation, and length of hospital stay, but not ICU admission or mortality.

Clinical Characteristics of Pandemic Influenza A (H1N1) 2009 Pediatric Infection in Busan and Gyeongsangnam-do: One Institution

Background

This study investigated the clinical characteristics and risk factors of the severity of pandemic influenza A (H1N1) 2009 infection in pediatric patients in Busan and Gyeongsangnam-do.

Methods

Cases of influenza A (H1N1) 2009 in patients under the age of 18 years, confirmed by reverse transcription polymerase chain reaction, at Pusan National University Hospital and Pusan National University Yangsan Hospital from the last week of August 2009 through the last week of February 2010 were retrospectively analyzed.

Results

Of the 3,777 confirmed cases of influenza A (H1N1) 2009, 2,200 (58.2%) were male and 1,577 (41.8%) were female. The average age of the patients was 8.4±4.8 years. The total cases peaked during 44th to 46th week. Most of the patients were in the 5- to 9-year-old age group. Oseltamivir was administered to 2,959 (78.3%) of the patients. 221 patients (5.9%) were hospitalized, age an average of 6.7±4.5 years. The average duration of hospitalization was 7.4±5.6 days. One hundred cases (45.2%) had pneumonia. Risk factors for hospitalization included male gender, <2 years of age, and underlying disease. Children with asthma were at very high risk of hospitalization, over 20 times the non-asthmatic children (odds ratio [OR], 21.684; confidence interval [CI], 13.295~39.791). Likewise the children with neurologic deficits faced a 16 times higher risk (OR, 15.738; CI, 7.961~31.111). Ten of the patients (4.5%) were admitted to the intensive care unit, and eight (3.6%) required mechanical ventilation.

Conclusion

Of the pediatric patients with pandemic influenza A (H1N1) 2009, most of the patients were in the 5- to 9-year-old age group. Risk factors for hospitalization included male gender, <2 years of age, and underlying disease. The most common complication was pneumonia. The very high risk of severe morbidity in children with asthma or neurologic disease shows the critical importance of targeted vaccine coverage, special awareness and swift care by both guardians and primary care providers.

Correlates of vaccine protection from influenza and its complications

Despite use of influenza vaccines for more than 65 y, influenza and its complications are a major cause of morbidity and mortality worldwide. Most deaths during influenza virus infections are due to underlying co-morbidities or secondary bacterial pneumonia. The measures of immune response currently used for licensure of influenza vaccines are relevant mainly for protection from viral infection in healthy adults. Development of new or improved influenza vaccines will require a definition of novel, and specific correlates of protection. These correlates should associate immune responses with outcomes that are relevant to specific risk groups, such as asthma exacerbation, hospitalization or disruptions to care or daily activities. Assessment of vaccine effectiveness for both viral and bacterial vaccines should include measures of impact on secondary bacterial pneumonia.

A retrospective cross-sectional study of risk factors and clinical spectrum of children admitted to hospital with pandemic H1N1 influenza as compared to influenza A

OBJECTIVE

To compare risk factors for severe disease as measured by admission to hospital and intensive care unit (ICU) and other clinical outcomes in children with pandemic H1N1 (pH1N1) versus those with seasonal influenza.

DESIGN

Retrospective analysis of children admitted to hospital with pH1N1 versus seasonal influenza A.

SETTING

Canadian tertiary referral children's hospital.

PARTICIPANTS

All laboratory-identified cases of pH1N1 in children younger than 18 years admitted to hospital in 2009 (n=176) and all seasonal influenza A cases admitted to hospital from influenza seasons 2004-2005 to 2008-2009 (n=200). Children with onset of symptoms more than 3 days after admission were excluded.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcomes include admission to hospital and ICU and need for mechanical ventilation. Secondary outcomes include length of stay in hospital and duration of supplemental oxygen requirement.

RESULTS

Children admitted with pH1N1 were older than seasonal influenza A admissions (hospital admission: 6.5 vs 3.3 years, p<0.01; ICU admission: 7.3 vs 3.6 years, p=0.02). Children hospitalised with pH1N1 were more likely to have a pre-existing diagnosis of asthma (15% vs 5%, p<0.01); however, there was no difference in the severity of pre-existing asthma between the two groups. After controlling for obesity, asthma (OR 4.59, 95% CI 1.42 to 14.81) and age ≥5 years (OR 2.87, 95% CI 1.60 to 5.16) were more common risk factors in admitted children with pH1N1. Asthma was a significant predictor of the need for intensive care in patients with pH1N1 (OR 4.56, 95% CI 1.16 to 17.89) but not in patients with seasonal influenza A.

CONCLUSION

While most pH1N1 cases presented with classic influenza-like symptoms, risk factors for severe pH1N1 disease differed from seasonal influenza A. Older age and asthma were associated with increased admission to hospital and ICU for children with pH1N1.

Mice with asthma are more resistant to influenza virus infection and NK cells activated by the induction of asthma have potentially protective effects

Purpose

This study was conducted in order to investigate whether the virulence of the influenza virus infection is affected by asthma in mice.

Methods

Mice with asthma or control mice were infected with influenza virus. The survival rate, body weight, virus titer, cytokine profile, and cell infiltration in bronchoalveolar lavage fluid (BALF) were measured. The NK cell cytotoxicity was determined by a co-culture system with YAC-1 cells, and the effects of NK cells were observed by depletion of NK cells using anti-asialoGM1 serum. The virus-specific CD8⁺ T cell killing assay was also performed.

Results

When asthmatic or control mice were infected with non- and sub-lethal doses of influenza virus, the asthmatic mice were more resistant to the virus than control mice with regard to the survival rate, the remission of body weight loss, and the virus burden. Anti-viral cytokines and the NK cell number were increased in the BALF of asthmatic mice before the infection. The NK cell cytotoxicity in the asthmatic mice was significantly enhanced compared to that in control mice, and the depletion of NK cells in asthmatic mice was abrogated both the improved survival rate and the recovery of the body weight loss. The antigen-specific CD8⁺ T cell killing activity in asthmatic mice was also significantly increased following the infection compared to that in control mice.

Conclusion

NK cell activated by the induction of asthma and the subsequently activated antigen-specific CD8⁺ T cells could promptly eliminate the viral-infected cells, thus leading to improvements in the morbidity and mortality of influenza virus infection.

Emergence of oseltamivir-resistant pandemic H1N1 in an immunocompetent child with severe status asthmaticus

INTRODUCTION

Pandemic influenza A (H1N1) may cause severe illness in pediatric patient with chronic lung disease.

CASE REPORT

We describe the emergence of oseltamivir resistance in an immunocompetent child with status asthmaticus triggered by pandemic influenza A (H1N1). This case highlights the possible relationship between influenza viral load and risk of resistance emergence in children with asthma. Influenza vaccination should continue to be emphasized as the mainstay of prevention in children with chronic lung disease.

CONCLUSION

Influenza virus can lead to severe status asthmaticus and can develop oseltamivir resistance in immunocompetent children.