The 2009 pandemic influenza A(H1N1) coincides with changes in the epidemiology of other viral pathogens causing acute respiratory tract infections in children

BACKGROUND

In Germany, the outbreak of the novel pandemic 2009 influenza A(H1N1) virus A(H1N1)pdm09 caused a wave of high activity between November 2009 and January 2011. The aim of this study was to investigate the prevalence of 19 respiratory pathogens in children hospitalized for lower respiratory tract infections during the winter influenza seasons of 2009/2010 and 2010/2011 and to observe a possible impact of influenza A(H1N1)pdm09 on the epidemiology of other epidemic viruses.

MATERIALS AND METHODS

Specimens were nasopharyngeal aspirates which had been collected from children admitted to the participating hospitals in the area of Mainz, Wiesbaden, and Kiel, Germany, with acute community-acquired lower respiratory tract infections. The specimens were subjected to a previously described multiplex reverse transcription PCR assay to detect the following microorganisms: enterovirus, influenza virus types A and B, respiratory syncytial virus (RSV), parainfluenzavirus types 1-4, adenovirus, Mycoplasma pneumoniae, Chlamydophila pneumoniae, rhinovirus, human metapneumovirus (hMPV), coronavirus OC43 and 229E, influenza A(H1N1)pdm09, Bordetella pertussis, Bordetella parapertussis, and Legionella pneumophila.

RESULTS

A total of 3,998 clinical specimens were collected from July 2009 to March 2011, of which 296 were positive for A(H1N1)pdm09. An epidemic of seasonal influenza A or B was not observed in the 2009/2010 season, but a minor epidemic of seasonal influenza B was observed in January/February 2011. Influenza A(H1N1)pdm09 coincided with the absence of the seasonal influenza A of former years. The RSV and hMPV epidemics of 2009/2010 erupted several weeks later than expected based on data collected in the PID-ARI-Network during the past 10 years, whereas in the 2010/2011 influenza season they occurred as expected.

CONCLUSIONS

The emergence of the novel influenza A(H1N1)pdm09 virus may have been influenced the epidemiology of other epidemic viruses, such as the RSV and hMPV. No epidemic of seasonal influenza was observed in the 2009/2010 influenza season.

Validation of a multiplex reverse transcriptase PCR ELISA for the detection of 19 respiratory tract pathogens

INTRODUCTION

Since acute respiratory tract infections inflict a high burden of disease in children worldwide, a multiplex reverse transcription polymerase chain reaction combined with a microwell hybridization assay (m-RT-PCR-ELISA) to detect 19 different respiratory pathogens was developed and validated.

METHODS

A total of 430 respiratory specimens were retrospectively tested in parallel by both the advanced 19-valent m-RT-PCR-ELISA as well as by culture or individual RT-PCR assays used in clinical routine.

RESULTS

The mean (median) sensitivity of the m-RT-PCR-ELISA in the retrospective test was 93.3% (95.1%; range 83.3-100 %), and the mean (median) specificity was 99.8 and 100 % (range 98.6-100 %), respectively. The mean positive predictive value was 99.3 % (range 93.4-100 %) and the mean negative predictive value was 95.3 % (range 98.4-100 %). Feasibility and clinical value of the 19-valent method was prospectively shown on 16,231 incoming clinical specimens from patients between 0 and 16 years of age with acute respiratory tract infections admitted to pediatric hospitals or private practices from October 2003 to June 2010 in three regions in Germany (Kiel, Mainz, Freiburg; Freiburg to June 2007 only). At least one microorganism was detected in 10,765 of 16,231 (66.3 %) clinical specimens: 5,044 RV, 1,999 RSV, 1,286 AV, 944 EV, 737 seasonal IVA, 173 pandemic IVA H1N1-2009, 899 MPV, 518 CV, 383 PIV3, 268 PIV1, 259 Mpn, 205 IVB, 164 PIV2, 144 PIV4, 103 Bp, 29 Cpn and 29 Bpp, while reovirus and Lpn were not present in these specimens from a pediatric population. More than one organism could be detected in 13.4 % of the specimens.

CONCLUSIONS

The m-RT-PCR-ELISA evaluated here improves the spectrum for diagnosing respiratory infections and is a feasible instrument for individual diagnostic and epidemiological studies.

Burden of disease in hospitalized RSV-positive children in Germany

BACKGROUND

In spite of a large amount of data from other countries, those on the burden of disease attributed to respiratory syncytial virus (RSV) in Germany are lacking and are urgently needed.

METHOD

In a population-based cross-sectional study from July 1996 to June 1999 150 children from birth to 16 years of age hospitalized in Kiel and tested positive for RSV by polymerase chain reaction were investigated. Stepwise linear and logistic regression models were applied to predict a bacterial co-infection as well as the duration of hospitalization.

RESULTS

Pneumonia (54 %) and wheezing bronchitis (including bronchiolitis, 27 %) were the predominating diagnoses; 25 % had an underlying condition. Four patients needed nasal continuous airway pressure and one intermittent mandatory ventilation; none died. According to the surrogate markers CRP and immature neutrophil fraction, 20 % to 30 % were suspected to have a bacterial co-infection on admission; antibiotics were prescribed in 65 % of the patients. The average duration of hospitalization was 9 days and was best predicted by young age, the presence of an underlying condition, intercostal retractions and high CRP on admission.

CONCLUSIONS

Bacterial co-infection is the major confounder in burden of disease analyses in RSV. The decision not to administer antibiotics to children hospitalized with RSV can be risky, particularly when there is considerable diagnostic uncertainty. Within the realm of current clinical practice, complications and deaths related to RSV are rare in Germany.