Contribution of influenza and respiratory syncytial virus to community cases of influenza-like illness: an observational study

Possible outcomes of reassortment in vivo between wild type and live attenuated influenza vaccine strains

Reassortment of influenza viruses in nature has been well documented. Genetic reassortment plays a key role in emergence of new influenza A strains, including pandemic viruses. Permissive host can be simultaneously coinfected with multiple influenza viruses. During genetic reassortment gene segments are exchanged between parental viruses that may lead to some enhancement of virulence of reassortant progeny. At present, vaccination with live attenuated cold-adapted (ca) reassortant vaccine (LAIV) is used as an effective public health measure for influenza prophylaxis. However, there are concerns about a potential of simultaneous infection of human host with ca and wild type (wt) influenza viruses which might produce progeny that contain novel, more virulent genotypes. The aim of this study was to investigate potential consequences of reassortment of wt with LAIV strains in vivo. We demonstrated that reassortment of wt viruses with ca strains in guinea pigs have resulted in progeny virus which caused reduced macroscopic lesions of chicken embryos. According to phenotypical data 95% (19 out of 20) isolated reassortants were restricted in replication at elevated temperature of 40°C. None of reassortants were more virulent than wt parents, or revealed significantly higher macroscopic lesions than wt parental viruses. Our results suggest that genetic reassortment between wt and vaccine strain is unlikely to lead to virulent reassortant progeny. These findings provide additional support of LAIV safety data.

The microarray technology: facts and controversies

Molecular diagnostic techniques for viral testing have undergone rapid development in recent years. They are becoming more widely used than the classical virological assays in the majority of clinical virology laboratories, and now represent a new method for the diagnosis of human viral infections. Recently, new techniques based on multiplex RT‐PCR amplification followed by microarray analysis have been developed and evaluated. On the basis of amplification of viral genome‐specific fragments by multiplex RT‐PCR and their subsequent detection via hybridization with microorganism‐specific binding probes on solid surfaces, they allow simultaneous detection and identification of multiple viruses in a single clinical sample. The management of viral central nervous system and respiratory tract infections currently represents the two main applications of the microarrays in routine virological practice. Microarrays have shown reliable results in comparison with those of referenced (RT)‐PCR assays, and appear to be of major interest for the detection of a broad range of respiratory and neurotropic viruses, assessment of the pathogenicity of newly discovered or neglected viruses, and identification of multiple viral infections in clinical samples. Despite several limitations observed during the different studies performed, this new technology might improve the clinical management of patients by enlarging the range of the viruses detected, in particular in cases of severe infections leading to patient hospitalization in the intensive‐care unit. They might also help in the prevention of nosocomial transmission in hospital departments by contributing to the development of new epidemiological surveillance systems for viral infections.

Neuraminidase inhibitors for preventing and treating influenza in children (published trials only)

BACKGROUND

During epidemics, influenza attack rates in children may exceed 40%. Options for prevention and treatment currently include the neuraminidase inhibitors zanamivir and oseltamivir. Laninamivir octanoate, the prodrug of laninamivir, is currently being developed.

OBJECTIVES

To assess the efficacy, safety and tolerability of neuraminidase inhibitors in the treatment and prevention of influenza in children.

SEARCH METHODS

For this update we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1) which includes the Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to January week 2, 2011) and EMBASE (January 2010 to January 2011).

SELECTION CRITERIA

Double-blind, randomised controlled trials (RCTs) comparing neuraminidase inhibitors with placebo or other antiviral drugs in children aged up to and including 12 years. We also included safety and tolerability data from other types of studies.

DATA COLLECTION AND ANALYSIS

Four review authors selected studies, assessed study quality and extracted data for the current and previous versions of this review. We analysed data separately for oseltamivir versus placebo, zanamivir versus placebo and laninamivir octanoate versus oseltamivir.

MAIN RESULTS

Six treatment trials involving 1906 children with clinical influenza and 450 children with influenza diagnosed on rapid near-patient influenza testing were included. Of these 2356 children, 1255 had laboratory-confirmed influenza. Three prophylaxis trials involving 863 children exposed to influenza were also included. In children with laboratory-confirmed influenza oseltamivir reduced median duration of illness by 36 hours (26%, P < 0.001). One trial of oseltamivir in children with asthma who had laboratory-confirmed influenza showed only a small reduction in illness duration (10.4 hours, 8%), which was not statistically significant (P = 0.542). Laninamivir octanoate 20 mg reduced symptom duration by 2.8 days (60%, P < 0.001) in children with oseltamivir-resistant influenza A/H1N1. Zanamivir reduced median duration of illness by 1.3 days (24%, P < 0.001). Oseltamivir significantly reduced acute otitis media in children aged one to five years with laboratory-confirmed influenza (risk difference (RD) -0.14, 95% confidence interval (CI) -0.24 to -0.04). Prophylaxis with either zanamivir or oseltamivir was associated with an 8% absolute reduction in developing influenza after the introduction of a case into a household (RD -0.08, 95% CI -0.12 to -0.05, P < 0.001). The adverse event profile of zanamivir was no worse than placebo but vomiting was more commonly associated with oseltamivir (number needed to harm = 17, 95% CI 10 to 34). The adverse event profiles of laninamivir octanoate and oseltamivir were similar.

AUTHORS' CONCLUSIONS

Oseltamivir and zanamivir appear to have modest benefit in reducing duration of illness in children with influenza. However, our analysis was limited by small sample sizes and an inability to pool data from different studies. In addition, the inclusion of data from published trials only may have resulted in significant publication bias. Based on published trial data, oseltamivir reduces the incidence of acute otitis media in children aged one to five years but is associated with a significantly increased risk of vomiting. One study demonstrated that laninamivir octanoate was more effective than oseltamivir in shortening duration of illness in children with oseltamivir-resistant influenza A/H1N1. The benefit of oseltamivir and zanamivir in preventing the transmission of influenza in households is modest and based on weak evidence. However, the clinical efficacy of neuraminidase inhibitors in 'at risk' children is still uncertain. Larger high-quality trials are needed with sufficient power to determine the efficacy of neuraminidase inhibitors in preventing serious complications of influenza (such as pneumonia or hospital admission), particularly in 'at risk' groups.

MF59™-adjuvanted seasonal influenza vaccine in young children

Influenza is a viral disease of the upper respiratory tract, which is manifested in seasonal epidemic waves associated with excess morbidity and mortality. Although efforts at prevention have traditionally been focused on the elderly, interest is growing on the specific features of influenza disease in children and the opportunities for prevention in this age group. Owing to recent improvements in surveillance schemes and diagnostic tools it has been realized that young children experience a burden of morbidity due to influenza as high or higher than the elderly and that children possibly act as a source of influenza infection and determinants of the intensity and the spread of influenza in the community, and as a result, the proposition that children should be preferentially targeted for influenza vaccination is gaining acceptance in many industrialized countries. Traditional seasonal inactivated influenza vaccines have performed poorly in the very young and the live-attenuated influenza vaccines, which are highly efficacious in this age group, have been associated with a poor safety profile in those less than 2 years of age. MF59™-adjuvanted influenza vaccines that were traditionally used in the elderly show a very promising safety and efficacy profile in the pediatric population that could overcome the limitations of the other currently available influenza vaccines for use in this age group.

Respiratory viruses involved in influenza-like illness in a Greek pediatric population during the winter period of the years 2005-2008

Viruses are the major cause of pediatric respiratory tract infection and yet many suspected cases of illness remain uncharacterized. This study aimed to determine the distribution of several respiratory viruses in children diagnosed as having influenza‐like illness, over the winter period of 2005–2008. Molecular assays including conventional and real time PCR protocols, were employed to screen respiratory specimens, collected by clinicians of the Influenza sentinel system and of outpatient pediatric clinics, for identification of several respiratory viruses. Of 1,272 specimens tested, 814 (64%) were positive for at least one virus and included 387 influenza viruses, 160 rhinoviruses, 155 respiratory syncytial viruses, 95 adenoviruses, 81 bocaviruses, 47 parainfluenza viruses, 44 metapneumoviruses, and 30 coronaviruses. Simultaneous presence of two or three viruses was observed in 173 of the above positive cases, 21% of which included influenza virus and rhinovirus. The majority of positive cases occurred during January and February. Influenza virus predominated in children older than 1 year old, with type B being the dominant type for the first season and subtypes A/H3N2 and A/H1N1 the following two winter seasons, respectively. Respiratory syncytial virus prevailed in children younger than 2 years old, with subtypes A and B alternating from year to year. This is the most comprehensive study of the epidemiology of respiratory viruses in Greece, indicating influenza, rhinovirus and respiratory syncytial virus as major contributors to influenza‐like illness in children. J. Med. Virol. 83:1841–1848, 2011. © 2011 Wiley‐Liss, Inc.

The unmet need in the elderly: how immunosenescence, CMV infection, co-morbidities and frailty are a challenge for the development of more effective influenza vaccines

Influenza remains the single most important cause of excess disability and mortality during the winter months. In spite of widespread influenza vaccination programs leading to demonstrated cost-savings in the over 65 population, hospitalization and death rates for acute respiratory illnesses continue to rise. As a person ages, increased serum levels of inflammatory cytokines are commonly recorded (TNF-α, IL-1, IL-6). Termed "inflammaging", this has been linked to persistent cytomegalovirus (CMV) infection and immune senescence, while increased anti-inflammatory cytokines (IL-10, TGF-β) are possibly associated with more healthy aging. Paradoxically, a shift with aging toward an anti-inflammatory (IL-10) response and decline in the IFN-γ:IL-10 ratio in influenza-challenged peripheral blood mononuclear cells is associated with a decline in the cytolytic capacity of CD8+ T cells responsible for clearing influenza virus from infected lung tissue. Thus, it is seemingly counter intuitive that the immune phenotype of healthy aging predicts a poor cell-mediated immune response and more serious outcomes of influenza. Herein we postulate a mechanistic link between the accumulation of late-stage, potentially terminally differentiated T cells, many or most of which result from CMV infection, and the immunopathogenesis of influenza infection, mediated by granzyme B in older adults. Further, adjuvanted influenza vaccines that stimulate inflammatory cytokines and suppress the IL-10 response to influenza challenge, would be expected to enhance protection in the 65+ population.

Neuraminidase inhibitors for preventing and treating influenza in children

BACKGROUND

During epidemics, influenza attack rates in children may exceed 40%. Options for prevention and treatment currently include the neuraminidase inhibitors zanamivir and oseltamivir. Laninamivir octanoate, the prodrug of laninamivir, is currently being developed.

OBJECTIVES

To assess the efficacy, safety and tolerability of neuraminidase inhibitors in the treatment and prevention of influenza in children.

SEARCH METHODS

For this update we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1) which includes the Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to January week 2, 2011) and EMBASE (January 2010 to January 2011).

SELECTION CRITERIA

Double-blind, randomised controlled trials (RCTs) comparing neuraminidase inhibitors with placebo or other antiviral drugs in children aged up to and including 12 years. We also included safety and tolerability data from other types of studies.

DATA COLLECTION AND ANALYSIS

Four review authors selected studies, assessed study quality and extracted data for the current and previous versions of this review. We analysed data separately for oseltamivir versus placebo, zanamivir versus placebo and laninamivir octanoate versus oseltamivir.

MAIN RESULTS

Six treatment trials involving 1906 children with clinical influenza and 450 children with influenza diagnosed on rapid near-patient influenza testing were included. Of these 2356 children, 1255 had laboratory-confirmed influenza. Three prophylaxis trials involving 863 children exposed to influenza were also included. In children with laboratory-confirmed influenza oseltamivir reduced median duration of illness by 36 hours (26%, P < 0.001). One trial of oseltamivir in children with asthma who had laboratory-confirmed influenza showed only a small reduction in illness duration (10.4 hours, 8%), which was not statistically significant (P = 0.542). Laninamivir octanoate 20 mg reduced symptom duration by 2.8 days (60%, P < 0.001) in children with oseltamivir-resistant influenza A/H1N1. Zanamivir reduced median duration of illness by 1.3 days (24%, P < 0.001). Oseltamivir significantly reduced acute otitis media in children aged one to five years with laboratory-confirmed influenza (risk difference (RD) -0.14, 95% confidence interval (CI) -0.24 to -0.04). Prophylaxis with either zanamivir or oseltamivir was associated with an 8% absolute reduction in developing influenza after the introduction of a case into a household (RD -0.08, 95% CI -0.12 to -0.05, P < 0.001). The adverse event profile of zanamivir was no worse than placebo but vomiting was more commonly associated with oseltamivir (number needed to harm = 17, 95% CI 10 to 34). The adverse event profiles of laninamivir octanoate and oseltamivir were similar.

AUTHORS' CONCLUSIONS

Oseltamivir and zanamivir appear to have modest benefit in reducing duration of illness in children with influenza. However, our analysis was limited by small sample sizes and an inability to pool data from different studies. Oseltamivir reduces the incidence of acute otitis media in children aged one to five years but is associated with a significantly increased risk of vomiting. One study demonstrated that laninamivir octanoate was more effective than oseltamivir in shortening duration of illness in children with oseltamivir-resistant influenza A/H1N1. The benefit of oseltamivir and zanamivir in preventing the transmission of influenza in households is modest and based on weak evidence. However, the clinical efficacy of neuraminidase inhibitors in 'at risk' children is still uncertain. Larger high-quality trials are needed with sufficient power to determine the efficacy of neuraminidase inhibitors in preventing serious complications of influenza (such as pneumonia or hospital admission), particularly in 'at risk' groups.

Etiology and clinical characteristics of influenza-like illness (ILI) in outpatients in Beijing, June 2010 to May 2011

Background

Since May 2009, exposure of the population of Beijing, China to pH1N1 has resulted in an increase in respiratory illnesses. Limited information is available on the etiology and clinical characteristics of the influenza-like illness (ILI) that ensued in adults following the pH1N1 pandemic.

Methods

Clinical and epidemiological data of ILI in adults was collected. A total of 279 throat swabs were tested for twelve respiratory viruses using multiplex RT-PCR. Clinical characteristics of influenza A in outpatients versus test-negative patients were compared using Pearson's χ2 and the Mann-Whitney U test. 190 swabs were tested for pH1N1 by virus isolation. Consultation rates for ILI were compared between 2009 and 2010.

Results

One or two virus were detected in 29% of the samples. Influenza A virus (FLU-A) accounted for 22.9% (64/279). Other viruses were present at a frequency less than 3.0%. Cough was significantly associated with Influenza A virus infection (χ2, p<0.001). The positive rate of FLU-A was consistent with changes in the ILI rate during the same period and there was a significant reduction in the incidence of ILI in 2010 when compared to 2009. During the 2010–2011 influenza season, the incidence peaked in January 2011 in Beijing and north China.

Conclusions

Exposure to pH1N1 had no impact on typical influenza seasonal peaks, although FLU-A remained the predominant virus for 2010 in Beijing. Symptomatically, cough was associated with FLU-A infection. The positive rate of influenza virus was consistent with changes in the ILI rate during the same period and there was a significant reduction in the incidence of ILI in 2010 when compared to that of 2009.

Pilot study of influenza vaccine effectiveness in urban Australian children attending childcare

BACKGROUND

Influenza outbreaks in the childcare setting are a significant cause of excess winter morbidity. This study explored methods of follow up and sample collection for a proposed randomised controlled trial of influenza vaccination in children attending childcare.

METHODS

The study was conducted in four Sydney childcare centres during 2007. Healthy children aged 6-59 months eligible for vaccination were recruited in two centres, with another two acting as controls. Data on influenza-like illness (ILI: ≥37.8°C plus at least one respiratory symptom) occurrence were collected weekly. In those children with an ILI, parents were asked to collect nasal swabs and send via surface mail for viral polymerase chain reaction. Vaccine efficacy (VE) for ILI was estimated overall and for subgroups aged 6-23 and 24-59 months using the formula VE = 1 - relative risk (RR).

RESULTS

Sixty-three per cent (151/238) of eligible children had parents give consent. Sixty-three children received influenza vaccine and 88 participated as controls. Of 26 specimens returned, a virus was detected in 18 (69%); none with influenza. Two symptomatic children had positive near-patient influenza tests in general practice (one a vaccine failure). The RR with 95% confidence interval in all children and those aged 6-23 months were less than one, 0.56 (0.32-1.02) and 0.46 (0.15-1.45), respectively.

CONCLUSIONS

This study demonstrated the feasibility and utility of parent-collected and mailed respiratory specimens for VE research in the childcare setting. Two-thirds of parent-collected swabs proved positive for at least one virus. Finding ways to reduce reluctance of parents to submit samples could improve the representativeness of samples collected and the power of the study. No evidence was found for influenza VE, but point estimates were in the direction of protection.

Signs and symptoms predicting influenza in children: a matched case-control analysis of prospectively collected clinical data

We aimed to determine whether there are signs or symptoms that could help clinicians to distinguish between influenza and other respiratory infections. The clinical data for this matched case-control analysis were derived from a 2-year prospective cohort study of respiratory infections among children aged≤13 years. At any signs of respiratory infection, the children were examined and nasal swabs were obtained for virologic analyses. Cases were 353 children with laboratory-confirmed influenza and controls were 353 children with respiratory symptoms who tested negative for influenza. Cases and controls were matched for gender, age, and timing of the visit. In the multivariate conditional logistic regression analyses, fever was the only sign that independently predicted influenza virus infection, with odds ratios ranging from 13.55 (95% confidence interval [CI], 6.90-26.63) to 50.10 (95% CI, 16.25-154.45), depending on the degree of fever. In all analyses, the predictive capability of fever increased with incremental elevations in the child's temperature. The likelihood ratio of fever≥40.0°C in predicting influenza was 6.00 (95% CI, 2.80-12.96). Among unselected children seen as outpatients during influenza outbreaks, fever is the only reliable predictor of influenza virus infection. The optimal use of influenza-specific antiviral drugs in children may require virologic confirmation.

Highly frequent infections with human rhinovirus in healthy young children: a longitudinal cohort study

BACKGROUND

Human rhinoviruses (HRVs) are an important cause of respiratory tract infections.

OBJECTIVES

We questioned whether the high prevalence rates of HRVs found in epidemiological studies is due to long-term individual continuity or a result of frequent infections with different HRV subtypes.

STUDY DESIGN

In a 6-month winter period 18 healthy controls, aged 0-7 years, were at least sampled every two weeks for HRV-PCR, irrespective of respiratory symptoms. All HRV positive samples were genotyped to determine HRV diversity.

RESULTS

In total 272 samples were collected. HRV was found in 101/272 (37%) samples. Genotyping revealed 27 different HRV subtypes. A median of 3.0 different HRV subtypes was found per child. Re-infections and continuity with identical HRV sequences were observed. The number of HRVs were higher in the youngest age group (p=0.01) and they had more different HRV subtypes (p=0.05) compared to oldest age group.

CONCLUSIONS

We found a high HRV exposition with a considerable diverse population of HRV subtypes in young children. These results have major implications for future research into the pathogenic role of HRV in respiratory diseases. Characterisation of subtypes will be necessary to discriminate between prolonged continuity and re-infections in patients with respiratory diseases.

Influenza surveillance among outpatients and inpatients in Morocco, 1996-2009

BACKGROUND

There is limited information about the epidemiology of influenza in Africa. We describe the epidemiology and seasonality of influenza in Morocco from 1996 to 2009 with particular emphasis on the 2007-2008 and 2008-2009 influenza seasons. Successes and challenges of the enhanced surveillance system introduced in 2007 are also discussed.

METHODS

Virologic sentinel surveillance for influenza virus was initiated in Morocco in 1996 using a network of private practitioners that collected oro-pharyngeal and naso-pharyngeal swabs from outpatients presenting with influenza-like-illness (ILI). The surveillance network expanded over the years to include inpatients presenting with severe acute respiratory illness (SARI) at hospitals and syndromic surveillance for ILI and acute respiratory infection (ARI). Respiratory samples and structured questionnaires were collected from eligible patients, and samples were tested by immunofluorescence assays and by viral isolation for influenza viruses.

RESULTS

We obtained a total of 6465 respiratory specimens during 1996 to 2009, of which, 3102 were collected during 2007-2009. Of those, 2249 (72%) were from patients with ILI, and 853 (27%) were from patients with SARI. Among the 3,102 patients, 98 (3%) had laboratory-confirmed influenza, of whom, 85 (87%) had ILI and 13 (13%) had SARI. Among ILI patients, the highest proportion of laboratory-confirmed influenza occurred in children less than 5 years of age (3/169; 2% during 2007-2008 and 23/271; 9% during 2008-2009) and patients 25-59 years of age (8/440; 2% during 2007-2009 and 21/483; 4% during 2008-2009). All SARI patients with influenza were less than 14 years of age. During all surveillance years, influenza virus circulation was seasonal with peak circulation during the winter months of October through April.

CONCLUSION

Influenza results in both mild and severe respiratory infections in Morocco, and accounted for a large proportion of all hospitalizations for severe respiratory illness among children 5 years of age and younger.

Effectiveness and safety of influenza vaccination in children: European perspective

Accumulating evidence for the substantial burden of influenza in children has increased interest in the vaccination of young children against influenza. So far, however, few European countries have issued official recommendations to vaccinate healthy children, which is largely due to the popular belief that inactivated influenza vaccines are ineffective in young children. Virologically confirmed studies performed during different seasons have yielded widely varying estimates for vaccine effectiveness and suggested that the match between the vaccine and the circulating strains of influenza viruses is one of the key drivers of the effectiveness of the vaccine. In seasons with good antigenic match, inactivated influenza vaccines are clearly effective also in children younger than 2 years of age. The live attenuated influenza vaccine provides even greater effectiveness in children, but the overall potential of this vaccine is limited by its licensure for only children older than 2 years of age. The safety record of seasonal inactivated influenza vaccines is excellent even in the youngest children.

Epidemiology of influenza-like illness during Pandemic (H1N1) 2009, New South Wales, Australia

To rapidly describe the epidemiology of influenza-like illness (ILI) during the 2009 winter epidemic of pandemic (H1N1) 2009 virus in New South Wales, Australia, we used results of a continuous population health survey. During July-September 2009, ILI was experienced by 23% of the population. Among these persons, 51% were unable to undertake normal duties for <3 days, 55% sought care at a general practice, and 5% went to a hospital. Factors independently associated with ILI were younger age, daily smoking, and obesity. Effectiveness of prepandemic seasonal vaccine was ?20%. The high prevalence of risk factors associated with a substantially increased risk for ILI deserves greater recognition.

Excess mortality associated with influenza epidemics in Portugal, 1980 to 2004

Background

Influenza epidemics have a substantial impact on human health, by increasing the mortality from pneumonia and influenza, respiratory and circulatory diseases, and all causes. This paper provides estimates of excess mortality rates associated with influenza virus circulation for 7 causes of death and 8 age groups in Portugal during the period of 1980–2004.

Methodology/Principal Findings

We compiled monthly mortality time series data by age for all-cause mortality, cerebrovascular diseases, ischemic heart diseases, diseases of the respiratory system, chronic respiratory diseases, pneumonia and influenza. We also used a control outcome, deaths from injuries. Age- and cause-specific baseline mortality was modelled by the ARIMA approach; excess deaths attributable to influenza were calculated by subtracting expected deaths from observed deaths during influenza epidemic periods. Influenza was associated with a seasonal average of 24.7 all-cause excess deaths per 100,000 inhabitants, approximately 90% of which were among seniors over 65 yrs. Excess mortality was 3–6 fold higher during seasons dominated by the A(H3N2) subtype than seasons dominated by A(H1N1)/B. High excess mortality impact was also seen in children under the age of four years. Seasonal excess mortality rates from all the studied causes of death were highly correlated with each other (Pearson correlation range, 0.65 to 0.95, P<0.001) and with seasonal rates of influenza-like-illness (ILI) among seniors over 65 years (Pearson correlation rho>0.64, P<0.05). By contrast, there was no correlation with excess mortality from injuries.

Conclusions/Significance

Our excess mortality approach is specific to influenza virus activity and produces influenza-related mortality rates for Portugal that are similar to those published for other countries. Our results indicate that all-cause excess mortality is a robust indicator of influenza burden in Portugal, and could be used to monitor the impact of influenza epidemics in this country. Additional studies are warranted to confirm these findings in other settings.

Nationwide surveillance of 18 respiratory viruses in patients with influenza-like illnesses: a pilot feasibility study in the French Sentinel Network

The aim of the present study was to test the feasibility of integrating the diagnosis of 18 respiratory viruses into clinical surveillance of influenza‐like illness using a PCR‐DNA microarray detection assay. The study took place in the French Sentinel Network, a nationwide surveillance network of General Practitioners (GPs) representative of French GPs in terms age, location, and type of practice (urban/rural). Three virological laboratories also participated in the study. The study was planned for 5 weeks from January 25, 2010 to February 27, 2010. A subset of 150 Sentinel GPs, located in mainland France, was enrolled to collect clinical data and nasopharyngeal samples from every first patient of the week having a medical visit for influenza‐like illness defined as a sudden fever of 39°C or more with respiratory symptoms and myalgia. Sixty‐three GPs (42%) collected 103 samples while 87 GPs (58%) did not. GPs did not differ with respect to their age, gender, urban/rural distribution, or years of inscription in the Sentinel Network. Patients included were of a similar age and had similar vaccination characteristics, but were more frequently men than influenza‐like illness patients reported to the network during the study period. Sixty‐one viruses were detected from 56 of 96 (58%) interpretable samples. The respiratory viruses detected most frequently were metapneumovirus and respiratory syncytial virus. This study showed that virological diagnosis of 18 respiratory viruses can be combined with surveillance of clinical influenza‐like illness in general practice. Although feasibility has not been demonstrated yet, it will be evaluated over the winter of 2010–2011. J. Med. Virol. 83:1451–1457, 2011. © 2011 Wiley‐Liss, Inc.

Monitoring epidemic viral respiratory infections using one-step real-time triplex RT-PCR targeting influenza A and B viruses and respiratory syncytial virus

Rapid and specific diagnosis of influenza A/B and respiratory syncytial virus (RSV) viruses is needed for optimal management of patients with acute respiratory infections. In this study, a one‐step triplex real‐time RT‐PCR assay was developed for rapid diagnosis of influenza A/B and RSV infections to optimize diagnosis efficiency of acute respiratory infections. Cell‐culture supernatants and clinical samples were used to evaluate specificity and sensitivity of the assay. The assay was used routinely during two winter epidemics for testing respiratory specimens from 2,417 patients. The limit of detection in cell‐culture supernatant was 1–10 plaque forming units/input (influenza A/B) and 2 × 10⁻² 50% tissue culture infectious dose/input (RSV). In clinical samples, the assay was as sensitive as commercial molecular assays for the detection of each influenza A/B and RSV (Flu‐A/B and RSV‐A/B r‐gene™) individually, and far more sensitive than antigen detection. During the winter 2008–2009, the assay identified 145 RSV, 42 influenza A, and one mixed RSV‐influenza A infections among 298 patients. The next winter, the assay was used in two independent hospital laboratory settings. 776 patients were tested in one hospital and 1,343 in the other, resulting in 184 and 501 RSV, 133 and 150 influenza A, and 1 and 11 mixed RSV‐influenza A infections, respectively, being detected. This new user‐friendly assay allows rapid (within hours), effective molecular diagnosis of single or mixed infections involving influenza A (including seasonal A H1N1 and H3N2, and A(H1N1) 2009), influenza B, and RSV(A/B). The assay is very valuable for managing patients during winter epidemics when influenza and respiratory syncytial viruses co‐circulate. J. Med. Virol. 83:695–701, 2011. © 2011 Wiley‐Liss, Inc.

Inactivated influenza vaccines: recent progress and implications for the elderly

The current public health strategy for the containment of influenza is annual vaccination, which is recommended for the elderly and for those in risk factor categories that present the highest morbidity and mortality. However, because the immune response in the elderly is known to be less vigorous than in younger adults, research in the last decade has focused on improving the immune response to vaccination and increasing the protection of aged populations. The decreased efficacy of vaccines in the elderly is due to several factors, such as a decrease in the number of Langerhans cells, the limited capacity of dendritic cells to present antigen, defects in the expression of Toll-like receptors and the reduced expression of MHC class I and II molecules. Also, production of mature naive T cells by the thymus decreases with age. Among several approaches proposed to address the need for more immunogenic vaccines compared with conventional agents, the most well proven is the use of adjuvants. The first licensed adjuvant, aluminium-based mineral salts (alum), introduced in the 1920s, remains the standard worldwide adjuvant for human use and it has been widely used for almost a century. However, the addition of alum adjuvant to a split or subunit influenza vaccine has induced only marginal improvements. Other adjuvants have been developed and approved for human use since 1997; in particular, MF59, an oil-in-water adjuvant emulsion of squalene, which is able to increase immunogenicity of seasonal, pre-pandemic and pandemic subunit vaccines while maintaining acceptable safety and tolerability profiles. More recently, another oil-in-water emulsion, AS03, has been approved as a component of pre-pandemic H5N1 and pandemic H1N1 2009 vaccines. Besides adjuvants, several other strategies have been assessed to enhance antibody response in the elderly and other less responsive subjects, such as high-dose antigen vaccines, carrier systems (liposomes/virosomes) and the intradermal route of immunization. In particular, the potential of intradermal vaccination is well documented and the recent availability of an appropriate injection system, which combines simplicity, safety and ease of use, has allowed evaluation of the tolerability, safety and immunogenicity of the intradermal influenza vaccine in large numbers of subjects. Data that emerged from large clinical trials showed an improved immunogenicity compared with that of standard vaccine. Observational studies or comparisons between adjuvanted, intradermal or high-dose versus conventional vaccines are needed to evaluate whether the greater immunogenicity observed in a number of recent studies is correlated with greater protection against influenza and influenza-related complications and death.

Has estimation of numbers of cases of pandemic influenza H1N1 in England in 2009 provided a useful measure of the occurrence of disease?

BACKGROUND

Surveillance indicators of influenza activity have generally provided robust comparative trend data for England. These indicators became less reliable, however, for monitoring trends in activity, or comparisons with previous years, during the influenza pandemic in 2009 because of changes in the perception of risk and changes in the systems of healthcare delivery. An approach was developed to estimate the number of cases of influenza-like illness (ILI) occurring because of infection with pandemic influenza virus.

METHODS AND FINDINGS

The number of cases was estimated each week in England on the basis of total number of patients consulting healthcare services with ILI; estimates of the proportion of individuals in the community experiencing an ILI-seeking health care; and the proportion of these positive on laboratory testing. Almost 800,000 cases (range 375,000-1·6 million) of symptomatic ILI cases were estimated to have occurred over the course of the two waves of pandemic activity in England. More cases were estimated to have occurred in the second wave than in the first.

CONCLUSIONS

These results underestimate the total number of infections as they do not include asymptomatic infections nor those with mild illness not meeting the definition of a case of ILI. Nevertheless, the case number estimates provide a useful indicator of the trend in influenza activity and weekly data were extensively used in media reports. Although surveillance methods differ between countries, the approach of synthesising available data sources to produce an overall estimate of case numbers could be applied more widely to provide comparative data.

Monitoring influenza activity in the United States: a comparison of traditional surveillance systems with Google Flu Trends

BACKGROUND

Google Flu Trends was developed to estimate US influenza-like illness (ILI) rates from internet searches; however ILI does not necessarily correlate with actual influenza virus infections.

METHODS AND FINDINGS

Influenza activity data from 2003-04 through 2007-08 were obtained from three US surveillance systems: Google Flu Trends, CDC Outpatient ILI Surveillance Network (CDC ILI Surveillance), and US Influenza Virologic Surveillance System (CDC Virus Surveillance). Pearson's correlation coefficients with 95% confidence intervals (95% CI) were calculated to compare surveillance data. An analysis was performed to investigate outlier observations and determine the extent to which they affected the correlations between surveillance data. Pearson's correlation coefficient describing Google Flu Trends and CDC Virus Surveillance over the study period was 0.72 (95% CI: 0.64, 0.79). The correlation between CDC ILI Surveillance and CDC Virus Surveillance over the same period was 0.85 (95% CI: 0.81, 0.89). Most of the outlier observations in both comparisons were from the 2003-04 influenza season. Exclusion of the outlier observations did not substantially improve the correlation between Google Flu Trends and CDC Virus Surveillance (0.82; 95% CI: 0.76, 0.87) or CDC ILI Surveillance and CDC Virus Surveillance (0.86; 95%CI: 0.82, 0.90).

CONCLUSIONS

This analysis demonstrates that while Google Flu Trends is highly correlated with rates of ILI, it has a lower correlation with surveillance for laboratory-confirmed influenza. Most of the outlier observations occurred during the 2003-04 influenza season that was characterized by early and intense influenza activity, which potentially altered health care seeking behavior, physician testing practices, and internet search behavior.

Incidence of influenza-related hospitalizations in different age groups of children in Finland: a 16-year study

BACKGROUND

children are frequently hospitalized with influenza-associated illnesses. Few virologically confirmed population-based studies of pediatric hospitalizations performed during several consecutive seasons are vailable.

METHODS

this 16-year retrospective study consisted of all children ≤ 16 years of age who were treated for virologically confirmed influenza at the Department of Pediatrics, Turku University Hospital, Finland, between July 1, 1988 and June 30, 2004. Calculation of the population-based rates of hospitalization in different age cohorts was based on children (n = 69,068) who lived within the 38 municipalities whose acute pediatric care was provided solely by Turku University Hospital.

RESULTS

during the study period, 401 children were hospitalized with virologically confirmed influenza. The average annual incidences of influenza-related hospitalizations were highest among children <6 months (276 [95% confidence interval, 220–336] per 100,000) and 6 to 11 months (173 [95% confidence interval, 129–220] per 100,000) of age. For both influenza A and B, the rates of hospitalization were highest among children younger than 1 year of age. Influenza A accounted for 82% and influenza B for 18% of all hospitalizations. A total of 40 (10.0%) children received treatment at the intensive care unit. Of all 401 children with confirmed influenza infection, only 216 (53.9%) had a discharge International Classification of Diseases code related to influenza.

CONCLUSIONS

the high incidence of influenza-associated hospitalization among infants less than 6 months of age underscores the need to find effective ways to prevent influenza in this age group, in which influenza vaccines are not currently licensed for use.

Cost-effectiveness of influenza vaccination of people aged 50-64 years in Australia: results are inconclusive

OBJECTIVE

Influenza cost-effectiveness studies use models for influenza clinical evolution based on a range of assumptions. We explore the importance of these assumptions and its implications in policy decisions.

METHODS

An influenza model was constructed to measure the cost-effectiveness of universal influenza vaccination of people over 50 years compared to current policy to vaccinate people over 65 years in Australia using available epidemiological data. We explored two scenarios, one with an Australian estimate of influenza like illness incidence, and one with a European estimate. Further, we estimated uncertainty of model structure and various parameter assumptions, and compared with a previous study.

RESULTS

The scenario and sensitivity analysis has shown the incremental cost-effectiveness ratio of the proposed compared to current policy varies from $112,000 to $6,000 per DALY. The model structure, parameter assumptions and limitations of existing epidemiological data lead to extensive unaccounted uncertainties in previous studies.

CONCLUSION

The lack of influenza epidemiological data makes the influenza cost-effectiveness studies that compare the universal influenza vaccinations of people over 50 years to current policy unreliable.

IMPLICATIONS

It is imperative to appraise unreliability of influenza cost-effectiveness studies in policy decisions. Research to acquire more data on influenza uncertainties in Australia should be funded.

Influenza surveillance in Shenzhen, the largest migratory metropolitan city of China, 2006–2009

Shenzhen is one of the largest migratory metropolitan cities in China. A standardized influenza surveillance system has been operating in Shenzhen for several years. The objectives of the present study were to describe the epidemiology of influenza in Shenzhen and to assess the impact of pandemic H1N1 on influenza activity. An average rate of 71 cases of influenza-like illness (ILI)/1000 consultations was reported, which was greater than the rate in the preceding 3 years. Laboratory surveillance showed that the annual proportion of specimens positive for influenza was 25·4% in 2009, representing a significant increase over the proportions of 5·4%, 11·6% and 12·2% in 2006, 2007 and 2008, respectively. A total of 414 ILI outbreaks were reported in 2009, which was a marked increase compared to the previous 3 years. Influenza activity reached a record high in Shenzhen in 2009. Seasonal A/H3N2 was the dominant strain during the summer and was gradually replaced by pandemic H1N1. A semi-annual cycle for influenza circulation began to appear due to the emergence of pandemic H1N1.

Including viral infection data supports an association between particulate pollution and respiratory admissions

OBJECTIVE

To refine and revise previous air pollution, climate and health time series analysis in Christchurch, New Zealand, introducing viral identification data (positive identification count and outbreak, defined as two of more positive tests).

METHOD

The effects on daily respiratory admissions for five years (1998-2002) of air pollution (PM(10) ), climate and virology (incorporating actual counts and outbreaks of influenza A and B (INF), para influenza virus type 3 (PIV) and respiratory syncytial virus (RSV) were examined using generalised additive models (GAMs), which are one of semiparametric models. Results were also compared with a model that included climate and air pollution parameters but without the inclusion of virology data. The data were analysed aggregately and then stratified by age group and season.

RESULTS

Different virology data detected various association levels. The highest estimates were a 3.93% (CI: 2.69-5.17) and a 3.88% (CI: 2.65-5.12) rise in respiratory admissions for a rise of 10 µg/m(3) annual PM(10) with outbreak and actual counts of PIV respectively for 0-19 years old with a three-day lag.

CONCLUSION

Refining a statistical model with the addition of virology data gives a similar estimation of the association between PM(10) levels and respiratory admissions to previous research. Use of the indicator of an outbreak of viral infection appears to be similar to actual count of viruses detected.

Altered cardiac rhythm in infants with bronchiolitis and respiratory syncytial virus infection

Background

Although the most frequent extra-pulmonary manifestations of respiratory syncytial virus (RSV) infection involve the cardiovascular system, no data regarding heart function in infants with bronchiolitis associated with RSV infection have yet been systematically collected. The aim of this study was to verify the real frequency of heart involvement in patients with bronchiolitis associated with RSV infection, and whether infants with mild or moderate disease also risk heart malfunction.

Methods

A total of 69 otherwise healthy infants aged 1-12 months with bronchiolitis hospitalised in standard wards were enrolled. Pernasal flocked swabs were performed to collect specimens for the detection of RSV by real-time polymerase chain reaction, and a blood sample was drawn to assess troponin I concentrations. On the day of admission, all of the infants underwent 24-hour Holter ECG monitoring and a complete heart evaluation with echocardiography. Patients were re-evaluated by investigators blinded to the etiological and cardiac findings four weeks after enrolment.

Results

Regardless of their clinical presentation, sinoatrial blocks were identified in 26/34 RSV-positive patients (76.5%) and 1/35 RSV-negative patients (2.9%) (p < 0.0001). The blocks recurred more than three times over 24 hours in 25/26 RSV-positive patients (96.2%) and none of the RSV-negative infants. Mean and maximum heart rates were significantly higher in the RSV-positive infants (p < 0.05), as was low-frequency power and the low and high-frequency power ratio (p < 0.05). The blocks were significantly more frequent in the children with an RSV load of ≥100,000 copies/mL than in those with a lower viral load (p < 0.0001). Holter ECG after 28 ± 3 days showed the complete regression of the heart abnormalities.

Conclusions

RSV seems associated with sinoatrial blocks and transient rhythm alterations even when the related respiratory problems are mild or moderate. Further studies are needed to clarify the mechanisms of these rhythm problems and whether they remain asymptomatic and transient even in presence of severe respiratory involvement or chronic underlying disease.

Respiratory syncytial virus and human rhinoviruses are the major causes of severe lower respiratory tract infections in Kuwait

Respiratory infections are very common in Kuwait, yet little is known about the cause of severe lower respiratory tract infections. This study was designed to investigate the viral cause of lower respiratory tract infections using sensitive molecular methods. PCR was applied to investigate 10 respiratory viruses in respiratory samples from 1,014 patients aged between 3 days to 76 years with acute lower respiratory tract infections. Of the 1,014 patients with lower respiratory tract infections, 288 (28.4%) had a viral infection. One hundred fifty‐five (53.8%) presented with bronchiolitis, 100 (43.7%) with pneumonia, and 33 (11.5%) with croup. One hundred six (36.8%) and 99 (34.4%) patients had evidence of respiratory syncytial virus and human rhinoviruses infections, respectively. Adenoviruses were detected in 44 (15.2%) patients, while influenza A virus in 21 (7.3%) patients. The majority of respiratory syncytial virus infections (84%) were among patients aged <1 year. Similarly, of the 99 patients infected by human rhinoviruses, 50 (50.5%) were also among this age group. In contrast, most of influenza A virus infections, 12 of 21 (57.1%), were among patients aged over 16 years. Parainfluenza virus‐2 and human coronaviruses were not detected in any of the patients' samples. Over the 3‐year period, most of the hospitalized patients were seen during the autumn and winter months from October through March. These data show that respiratory syncytial virus and human rhinoviruses may be the major causes of lower respiratory tract infections in children admitted to hospital in Kuwait. J. Med. Virol. 82:1462–1467, 2010. © 2010 Wiley‐Liss, Inc.

Respiratory syncytial virus infections in the adult asthmatic--mechanisms of host susceptibility and viral subversion

Respiratory syncytial virus (RSV), a single-stranded RNA virus of the Paramyxoviridae family, is a major cause of bronchiolitis in infants and is also conjectured to be an early-life influence on the development of asthma. Although the data supporting a role for RSV in bronchiolitis in children are robust and evidence to support its role in juvenile asthmatics exists, RSV's role in asthma pathogenesis in adults is not as clearly defined. The authors review the literature to further elucidate RSV's impact on adult asthmatics, including its importance as a cause of asthma exacerbations. They examine the morbidity associated with RSV infection and how the immune response may differ between adult asthmatics and nonasthmatics. They review the responses by specific cell types from adults with asthma that are stimulated by RSV. They also consider the role of early-life exposure to RSV and its contribution to asthma in adults. Lastly, they review the mechanisms by which RSV evades normal host immune responses and subverts these responses to its benefit.

Rapid detection of respiratory tract viral infections and coinfections in patients with influenza-like illnesses by use of reverse transcription-PCR DNA microarray systems

We prospectively tested 95 nasal swabs or nasopharyngeal aspirates taken from 56 adults and 39 children visiting the Reims University Medical Centre (northern France) for influenza-like illnesses (ILI) during the early stage of the French influenza A/H1N1v pandemic (October 2009). Respiratory samples were tested using a combination of two commercially available reverse transcription-PCR (RT-PCR) DNA microarray systems allowing rapid detection of influenza A virus strains, including the new A/H1N1v strain as well as 20 other common or newly discovered respiratory viruses. Concomitantly, a generic and classical real-time RT-PCR assay was performed to detect all circulating influenza A virus strains in the same samples. Of the 95 respiratory samples tested, 30 (31%) were positive for the detection of influenza A/H1N1v virus infection by both RT-PCR DNA microarray and classical real-time RT-PCR detection assays. Among the infections, 25 (83%) were monoinfections, whereas 5 (17%) were multiple infections associating influenza A/H1N1v virus with coronavirus (CoV), human bocavirus (HBoV), respiratory syncytial virus (RSV), or human rhinoviruses (HRVs). Of the 95 respiratory samples tested, 35 (37%) were positive for respiratory viruses other than influenza A/H1N1v virus. Among these infections, we observed 30 monoinfections (HRVs [63%], parainfluenza viruses [PIVs] [20%]), influenza A/H3N2 virus [6%], coronavirus [4%], and HBoV [4%]) and 5 multiple infections, in which HRVs and PIVs were the most frequently detected viruses. No specific single or mixed viral infections appeared to be associated significantly with secondary hospitalization in infectious disease or intensive care departments during the study period (P > 0.5). The use of RT-PCR DNA microarray systems in clinical virology practice allows the rapid and accurate detection of conventional and newly discovered viral respiratory pathogens in patients suffering from ILI and therefore could be of major interest for development of new epidemiological survey systems for respiratory viral infections.

Ten years of global evolution of the human respiratory syncytial virus BA genotype with a 60-nucleotide duplication in the G protein gene

The emergence of natural isolates of human respiratory syncytial virus group B (HRSV-B) with a 60-nucleotide (nt) duplication in the G protein gene in Buenos Aires, Argentina, in 1999 (A. Trento et al., J. Gen. Virol. 84:3115-3120, 2003) and their dissemination worldwide allowed us to use the duplicated segment as a natural tag to examine in detail the evolution of HRSV during propagation in its natural host. Viruses with the duplicated segment were all clustered in a new genotype, named BA (A. Trento et al., J. Virol. 80:975-984, 2006). To obtain information about the prevalence of these viruses in Spain, we tested for the presence of the duplicated segment in positive HRSV-B clinical samples collected at the Severo Ochoa Hospital (Madrid) during 12 consecutive epidemics (1996-1997 to 2007-2008). Viruses with the 60-nt duplication were found in 61 samples, with a high prevalence relative to the rest of B genotypes in the most recent seasons. Global phylogenetic and demographic analysis of all G sequences containing the duplication, collected across five continents up until April 2009, revealed that the prevalence of the BA genotype increased gradually until 2004-2005, despite its rapid dissemination worldwide. After that date and coinciding with a bottleneck effect on the population size, a relatively new BA lineage (BA-IV) replaced all other group B viruses, suggesting further adaptation of the BA genotype to its natural host.

Influenza in outpatient ILI case-patients in national hospital-based surveillance, Bangladesh, 2007-2008

BACKGROUND

Recent population-based estimates in a Dhaka low-income community suggest that influenza was prevalent among children. To explore the epidemiology and seasonality of influenza throughout the country and among all age groups, we established nationally representative hospital-based surveillance necessary to guide influenza prevention and control efforts.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted influenza-like illness and severe acute respiratory illness sentinel surveillance in 12 hospitals across Bangladesh during May 2007-December 2008. We collected specimens from 3,699 patients, 385 (10%) which were influenza positive by real time RT-PCR. Among the sample-positive patients, 192 (51%) were type A and 188 (49%) were type B. Hemagglutinin subtyping of type A viruses detected 137 (71%) A/H1 and 55 (29%) A/H3, but no A/H5 or other novel influenza strains. The frequency of influenza cases was highest among children aged under 5 years (44%), while the proportions of laboratory confirmed cases was highest among participants aged 11-15 (18%). We applied kriging, a geo-statistical technique, to explore the spatial and temporal spread of influenza and found that, during 2008, influenza was first identified in large port cities and then gradually spread to other parts of the country. We identified a distinct influenza peak during the rainy season (May-September).

CONCLUSIONS/SIGNIFICANCE

Our surveillance data confirms that influenza is prevalent throughout Bangladesh, affecting a wide range of ages and causing considerable morbidity and hospital care. A unimodal influenza seasonality may allow Bangladesh to time annual influenza prevention messages and vaccination campaigns to reduce the national influenza burden. To scale-up such national interventions, we need to quantify the national rates of influenza and the economic burden associated with this disease through further studies.

The level and duration of RSV-specific maternal IgG in infants in Kilifi Kenya

Background

Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infection in infants. The rate of decay of RSV-specific maternal antibodies (RSV-matAb), the factors affecting cord blood levels, and the relationship between these levels and protection from infection are poorly defined.

Methods

A birth cohort (n = 635) in rural Kenya, was studied intensively to monitor infections and describe age-related serological characteristics. RSV specific IgG antibody (Ab) in serum was measured by the enzyme linked immunosorbent assay (ELISA) in cord blood, consecutive samples taken 3 monthly, and in paired acute and convalescent samples. A linear regression model was used to calculate the rate of RSV-matAb decline. The effect of risk factors on cord blood titres was investigated.

Results

The half-life of matAb in the Kenyan cohort was calculated to be 79 days (95% confidence limits (CL): 76–81 days). Ninety seven percent of infants were born with RSV-matAb. Infants who subsequently experienced an infection in early life had significantly lower cord titres of anti-RSV Ab in comparison to infants who did not have any incident infection in the first 6 months (P = 0.011). RSV infections were shown to have no effect on the rate of decay of RSV-matAb.

Conclusion

Maternal-specific RSV Ab decline rapidly following birth. However, we provide evidence of protection against severe disease by RSV-matAb during the first 6–7 months. This suggests that boosting maternal-specific Ab by RSV vaccination may be a useful strategy to consider.

Effects of aging on the adaptive immune response to respiratory virus infections

Severe acute respiratory disease caused by respiratory virus infections in individuals aged 65 years and older and in high-risk adults, such as those with chronic cardiopulmonary disorders, is associated with increased hospitalization and mortality rates. Epidemiological studies have identified influenza virus and respiratory syncytial virus as the most frequent causes of virus-induced respiratory disease in elderly and high-risk adults. Studies in both humans and animal models have established fundamental defects in cell-mediated and humoral immune responses in aged individuals. However, it is not well understood how age specifically alters the immune response to respiratory pathogens. In this review, we will focus our discussion on the major causative agents of severe respiratory virus infections in elderly and high-risk adults and the age-associated defects in the immune response that probably contribute to the increased disease severity observed in these populations.

Respiratory syncytial virus and other respiratory viruses in the setting of bone marrow transplantation

PURPOSE OF REVIEW

Several epidemiologic studies have enhanced our understanding of the impact of respiratory viruses on bone marrow transplant recipients.

RECENT FINDINGS

Respiratory viral infections occur frequently following stem cell transplantation but present atypically. Many patients have asymptomatic infections. There is a growing armamentarium of antiviral agents currently under development, although prospective studies in transplant patients are needed.

SUMMARY

Respiratory viral infections occur frequently after hematopoietic stem cell transplant. Newer agents may prove useful in the prevention and treatment of respiratory viral infections in this population.

Monitoring the emergence of community transmission of influenza A/H1N1 2009 in England: a cross sectional opportunistic survey of self sampled telephone callers to NHS Direct

OBJECTIVE

To evaluate ascertainment of the onset of community transmission of influenza A/H1N1 2009 (swine flu) in England during the earliest phase of the epidemic through comparing data from two surveillance systems.

DESIGN

Cross sectional opportunistic survey.

STUDY SAMPLES

Results from self samples by consenting patients who had called the NHS Direct telephone health line with cold or flu symptoms, or both, and results from Health Protection Agency (HPA) regional microbiology laboratories on patients tested according to the clinical algorithm for the management of suspected cases of swine flu.

SETTING

Six regions of England between 24 May and 30 June 2009.

MAIN OUTCOME MEASURE

Proportion of specimens with laboratory evidence of influenza A/H1N1 2009.

RESULTS

Influenza A/H1N1 2009 infections were detected in 91 (7%) of the 1385 self sampled specimens tested. In addition, eight instances of influenza A/H3 infection and two cases of influenza B infection were detected. The weekly rate of change in the proportions of infected individuals according to self obtained samples closely matched the rate of increase in the proportions of infected people reported by HPA regional laboratories. Comparing the data from both systems showed that local community transmission was occurring in London and the West Midlands once HPA regional laboratories began detecting 100 or more influenza A/H1N1 2009 infections, or a proportion positive of over 20% of those tested, each week.

CONCLUSIONS

Trends in the proportion of patients with influenza A/H1N1 2009 across regions detected through clinical management were mirrored by the proportion of NHS Direct callers with laboratory confirmed infection. The initial concern that information from HPA regional laboratory reports would be too limited because it was based on testing patients with either travel associated risk or who were contacts of other influenza cases was unfounded. Reports from HPA regional laboratories could be used to recognise the extent to which local community transmission was occurring.

Epidemiological study of influenza virus infections in young adult outpatients from Buenos Aires, Argentina

Background  Influenza virus is the most common cause of influenza‐like illness (ILI) in adults. In Argentina, studies on influenza and other respiratory viruses were performed mostly in pediatric populations.

Objectives  To determine: (1) the frequency of influenza virus and other common respiratory viruses in adult outpatients with ILI, (2) whether the signs and symptoms predict viral etiology, (3) whether viral diagnosis changes clinical management or infection control measures and (4) to characterize the influenza strains circulating in the community.

Population and methods  Nasal and pharyngeal swabs from adult outpatients with ILI attending the emergency room during the winter seasons of 2004 and 2005 in Argentina were evaluated by immunofluorescence and RT‐PCR.

Results  Of 151 samples analyzed, 39 (26%) were influenza A positive, 5 (3·3%) influenza B positive and 4 (2·6%) respiratory syncytial virus positive by immunofluorescence. Two samples (1·3%) were human metapneumovirus positive by RT PCR. Cell culture detected six additional influenza viruses and one adenovirus positive sample. The sensitivity of immunofluorescence for influenza compared with culture was 70%. Symptoms did not predict etiology.

Conclusions  In this study, 40% of the patients with ILI had a specific viral infection and 83% were influenza viruses. Viral detection was necessary to determine the etiology as signs and symptoms were not different between patients with or without viral infection. Viral diagnosis was important to implement infectious control measures. Circulating influenza strains in this study were similar to the correspondent vaccine strains selected for the Southern hemisphere.

Respiratory syncytial virus: an important cause of acute respiratory illness among young adults undergoing military training

Background  Military recruits receiving training are vulnerable to acute respiratory disease and a significant proportion of illness is caused by unidentified pathogens. While some countries use surveillance programmes to monitor such illness, few data exist for recruits of the British Armed Forces.

Objectives  Through active surveillance of approximately 1000 Royal Navy trainees during 2001, we sought to describe and determine the aetiology of acute respiratory illness.

Methods  Standard viral culture was used together with serology and a novel highly sensitive real‐time PCR and molecular beacon probe assay for respiratory syncytial virus (RSV) detection.

Results  Among 54 Royal Navy recruits with respiratory symptoms adenovirus was identified in 35%, influenza viruses in 19% and RSV in 14%. All recruits were absent from training for almost a week, most of whom were confined to the sickbay.

Conclusions  This study is the first to document adenovirus and RSV as important causes of acute respiratory illness among Royal Navy trainees. The study findings demonstrate the clinical significance and challenges of diagnosing RSV infection in young adults.

Prevalence and seasonality of influenza-like illness in children, Nicaragua, 2005-2007

Case rates were high and had marked seasonal peaks.

Although information about seasonality and prevalence of influenza is crucial for development of effective prevention and control strategies, limited data exist on the epidemiology of influenza in tropical countries. To better understand influenza in Nicaragua, we performed a prospective 2-year cohort study of influenza-like illness (ILI) involving 4,276 children, 2–11 years of age, in Managua, during April 2005–April 2007. One peak of ILI activity occurred during 2005, in June–July; 2 peaks occurred during 2006, in June–July and November–December. The rate of ILI was 34.8/100 person-years. A household risk factor survey administered to a subset (61%) of participants identified the following risk factors: young age, asthma, and increasing person density in the household. Influenza virus circulation was confirmed during each ILI peak by laboratory testing of a subset of samples. Our findings demonstrate a high rate of ILI, with seasonal peaks, in children in Nicaragua.

[Comparison study of a real-time reverse transcription polymerase chain reaction assay with an enzyme immunoassay and shell vial culture for influenza A and B virus detection in adult patients]

INTRODUCTION

The age of the patients and the type of sample are major problems in the diagnosis of influenza. Most available diagnostic techniques are highly effective in pediatric patients and in nasopharyngeal aspirates. However, in the adult population and using throat swabs, these techniques are much less reliable.

AIM

We performed a prospective study comparing the efficacy of a commercial real-time reverse transcription PCR assay (RT-PCR) with that of an enzyme immunoassay (EIA) or shell vial culture (SV) in the detection of influenza A and B viruses in 125 throat swabs from adults with clinically suspected influenza during the 2007-2008 flu season.

MATERIAL AND METHODS

Throat swabs were subjected to rapid antigen detection for influenza viruses by means of a commercial dot-blot EIA. For the RT-PCR technique, RNA was extracted from 200 microL of each sample by the automated extraction system, EZ1 virus minikit (version 2.0). Genomic amplification of the extracted viral RNA was carried out using the OneStep RT-PCR FluA+FluB automated system with the SmartCycler amplification system. Each sample was inoculated into 2 SV of the MDCK cell line. Turnaround times were calculated from the time specimens were received in the laboratory to the time the result was reported to clinicians.

RESULTS

The EIA system detected 27 (21.6%) positive samples, RT-PCR 62 (49.6%) positive samples, and SV 56 (44.8%) positive samples. Among the 62 positive samples, EIA detected 27 (43.5%), RT-PCR 62 (100%) and SV 56 (90.3%). With the use of RT-PCR, 38.4% of the adults studied were diagnosed on the same day samples were received. Among the total, 67.2% of diagnostic results were obtained within the first 24 hours; turnaround time was 1.1 days.

CONCLUSION

The real-time RT-PCR method studied displayed high sensitivity and specificity in the detection of influenza virus in adult patients, when compared with the conventional techniques. With real-time RT-PCR, large numbers of samples can be rapidly tested and results provided the same day samples are received.

Macrolide antibiotics inhibit respiratory syncytial virus infection in human airway epithelial cells

To examine the effects of macrolide antibiotics on RS virus infection in airways, human tracheal epithelial cells were pre-treated with bafilomycin A(1) and clarithromycin, and infected with RS virus. Viral titers in supernatant fluids and RNA of RS virus, and concentrations of cytokines in supernatant fluids, including interleukin-6 increased with time after infection. Bafilomycin A(1) and clarithromycin reduced viral titers in supernatant fluids of RS virus, RNA of RS virus, the susceptibility to RS virus infection, and concentrations of cytokines induced by virus infection. N-acetyl-S-geranylgeranyl-L-cysteine, an inhibitor for a small GTP binding protein of RhoA, isoform A of the Ras-homologus (Rho) family, an active form of which is associated with RS virus infection via binding to its fusion protein (F protein), reduced viral titers in supernatant fluids and RNA of RS virus. Bafilomycin A(1) and clarithromycin inhibited RhoA activation induced by lysophosphatidic acid in the cells. Fasudil, an inhibitor of Rho kinase, also reduced viral titers in supernatant fluids and RNA of RS virus. These findings suggest that macrolide antibiotics may inhibit RS virus infection, partly through the reduced expression of F protein receptor, activated RhoA, and the inhibition of subsequent Rho kinase activation in human airway epithelial cells.

Clinical presentation of influenza in unselected children treated as outpatients

BACKGROUND

Influenza causes a great disease burden on children especially in the outpatient setting. The signs and symptoms of influenza in unselected children treated as outpatients have not been previously published.

METHODS

We assessed the clinical presentation of influenza in a prospective study of respiratory infections in preenrolled cohorts of children < or =13 years of age during 2 consecutive respiratory seasons (2231 child-seasons of follow-up). We examined the children and obtained a nasal swab for the detection of influenza during every episode of illness, regardless of the presence or absence of fever or the severity of the symptoms.

RESULTS

Influenza was virologically confirmed in 372 children, of whom 353 (95%) providing complete data on the signs and symptoms were included in the analyses. A total of 95% of these children were febrile, and 50% had fever > or =39.0 degrees C. Among children <3 years of age, 20% had fever > or =40.0 degrees C. Seventy-seven percent of the children had cough and 78% had rhinitis. In children 7 to 13 years of age, only 39% had headache and 13% had myalgia.

CONCLUSIONS

High fever is a prominent sign of influenza in children, and the clinical presentation of influenza is most severe in children <3 years of age. Headache and myalgia are not typical features of influenza in outpatient children. Most children with influenza have rhinitis during the early phase of the illness, which makes the clinical diagnosis of influenza difficult especially in the youngest children.

Viral Infections

Although influenza remains indisputably the most significant viral pathogen in adults, other viruses such as respiratory syncytial virus, parainfluenza viruses, and human metapneumovirus are now recognized as significant pathogens in older populations.

Oseltamivir and zanamivir are antiviral agents that are effective for the treatment and prophylaxis of influenza A and B. For treatment and for optimal effect, therapy should be initiated within 48 h of symptom onset.

Infection with hepatitis viruses may be more severe in older adults with more fulminate disease as observed with acute hepatitis A and a more rapid progression to cirrhosis with hepatitis C.

Outbreaks of viral gastroenteritis are common in long-term care facilities, and infection may lead to death due to dehydration and oliguria.

The incidence of herpes zoster increases with advancing age and carries with it a significant risk of post herpetic neuralgia. The use of antiviral medications and corticosteroids may reduce the incidence and severity of chronic pain.

Common respiratory infections diagnosed in general practice

Acute respiratory infections are one of the most common causes for presentation to a general practitioner. The range of symptoms associated with each infection can be wide ranging in both presentation and severity, depending on age of the patient, underlying co-morbidities and other confounding factors. In this chapter we describe the most common respiratory infections ranging from relatively mild infections such as the common cold, through to more serious presentations including pneumonia. Data are presented from a general practitioner morbidity surveillance system based in England and Wales. Each acute respiratory syndrome is described in respect of seasonality, secular trends and microbiological aetiology providing an insight into the complex nature of these acute respiratory episodes. The more serious endpoints of acute respiratory infections are hospitalisation and death. Many acute respiratory infections are mild in nature and generally self-limiting and therefore do not commonly require further medical interventions. However, despite major advances in the prevention and treatment of acute respiratory infections in recent years, hospitalisation and deaths continue to exert pressures on national health resources and provide an economic burden in countries across the world on an annual basis.

[Lower respiratory tract infections with influenza and respiratory syncytial viruses in hospitalized elderly patients during the 2005-2006 winter season]

OBJECTIVES

To assess the proportion of lower respiratory tract infections (LRTI) attributable to influenza virus and respiratory syncytial virus (RSV) during the 2005-2006 winter period, among hospitalized elderly in a geriatric unit of a French hospital near Paris and and describe the characteristics of these infections.

METHODS

In a geriatric unit with 115 beds, distributed as 14 in acute care (ACF), 21 in rehabilitation and intermediate-care (RICF) and 80 in long-term-care-facilities (LTCF), all patients over age 65 with LRTI were enrolled during a winter. Clinical and biological parameters were recorded including paired serology for influenza virus and RSV.

RESULTS

54 LRTI concerned 47 patients were recorded. 50 paired serums were analysed. Influenza virus or RSV were found in 17 cases (34%). The distribution of the cases was as follows: Influenza A in 5 cases, Influenza B in 3 cases, a co-infection with influenza A and B in 4 cases, RSV in 3 cases and co-infections with influenza and RSV in 2 cases (influenza A and RSV in one case and influenza A and B and RSV in the other case). 7 cases concerned patients in ACF, in 3 cases patients were in RICF and in 7 cases patients were in LTCF. 15 cases were nosocomial infections. 11 patients infected by influenza virus were vaccined. It was concluded as bronchitis in 8 cases, interstitial pneumonia in 6 cases and alveolar pneumonia in 3 cases. Antibiotics were prescribed in 11 cases. In one case the evolution was unfavourable with death. Patients with influenza or RSV infections had significantly more rales and rhonchi compared with patients non infected by these virus (p<0.05).

CONCLUSION

Influenza and RSV are an important cause of LRTI in elderly during the winter months, influenza infections can occurring among vaccinated elderly. It seems necessary to achieve further clinical studies about LRTI in elderly and to study the impact of rapid diagnostic tests to improve the management of these infections.

Effects of influenza plus pneumococcal conjugate vaccination versus influenza vaccination alone in preventing respiratory tract infections in children: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To evaluate the effects of influenza vaccination with or without heptavalent pneumococcal conjugate vaccination on respiratory tract infections (RTIs) in children.

STUDY DESIGN

This was a randomized, double-blind, placebo-controlled trial comprising 579 children age 18 to 72 months with a previous history of physician-diagnosed RTI, recruited between 2003 and 2005. The children were assigned to 2 doses of parenteral inactivated trivalent subunit influenza plus heptavalent pneumococcal conjugate vaccination (TIV+PCV7), influenza plus placebo vaccination (TIV+plac), or control hepatitis B virus vaccination plus placebo (HBV+plac). Main outcome measures were febrile RTI and related polymerase chain reaction (PCR)-confirmed influenza, primary care visits, antibiotic prescriptions, and acute otitis media (AOM) episodes.

RESULTS

During influenza seasons, febrile RTI were reduced by 24% (95% confidence interval [CI] = 1% to 42%) in the TIV+PCV7 group and by 13% (95% CI = -12% to 32%) in the TIV+plac group compared with the control group. The occurrence of PCR-confirmed influenza was reduced by 52% (95% CI = 7% to 75%) in the TIV+PCV7 group and by 51% (95% CI = 3% to 75%) in the TIV+plac group. Episodes of AOM were reduced by 57% (95% CI = 6% to 80%) in the TIV+PCV7 group and by 71% (95% CI = 30% to 88%) in the TIV+plac group. Outside of the influenza seasons, no significant effects of vaccinations were demonstrated on the studied outcomes.

CONCLUSIONS

During influenza seasons, influenza vaccination with or without pneumococcal conjugate vaccination substantially reduced cases of confirmed influenza and AOM episodes.