Respiratory viral infections during the 2009-2010 winter season in Central England, UK: incidence and patterns of multiple virus co-infections.

Acute viral respiratory infections are the most common infections in humans. Co-infection with different respiratory viruses is well documented but not necessarily well understood. The aim of this study was to utilise laboratory data from the winter season following the 2009 influenza A(H1N1) outbreak to investigate rates of respiratory virus co-infections, virus prevalence in different age groups and temporal variations in virus detection. The Health Protection Agency Public Health Laboratory (HPA PHL) Birmingham, UK, routinely uses polymerase chain reaction (PCR) to detect common respiratory viruses. The results from specimens received for respiratory virus investigations from late September 2009 to April 2010 were analysed. A total of 4,821 specimen results were analysed. Of these, 323 (13.2 %) had co-detections of two viruses, 22 (0.9 %) had three viruses and four (0.2 %) had four viruses. Reciprocal patterns of positive or negative associations between different virus pairs were found. Statistical analysis confirmed the significance of negative associations between influenza A and human metapneumovirus (HMPV), and influenza A and rhinovirus. Positive associations between parainfluenza with rhinovirus, rhinovirus with respiratory syncytial virus (RSV) and adenovirus with rhinovirus, parainfluenza and RSV were also significant. Age and temporal distributions of the different viruses were typical. This study found that the co-detection of different respiratory viruses is not random and most associations are reciprocal, either positively or negatively. The pandemic strain of influenza A(H1N1) was notable in that it was the least likely to be co-detected with another respiratory virus

Impact of human metapneumovirus infection on in and outpatients for the years 2006-2008 in Southern Brazil

The human metapneumovirus (hMPV), member of the Paramyxoviridae family, has been reported as an important agent involved with acute respiratory infections (ARIs). The aim of this study is to identify hMPV as the etiological agent of ARIs on in and outpatients in the city of Curitiba, Southern Brazil, and describe clinical data of hMPV subtyping. A retrospective study was performed in 1,572 respiratory samples over a period of three years. hMPV was detected by reverse transcription-polymerase chain reaction and subtyping was performed by nucleotide sequencing. hMPV was present in 61 (3.9%) samples and subtypes A1, A2a, B1 and B2 were detected. The incidence of hMPV was higher in outpatients (5.9%), whose mean age was 19.7 years (range 6 months-75 years old), than in inpatients (3%), whose mean age was 7.6 months (range 1 month-26 years old). The outpatients had upper respiratory tract infections with flu-like symptoms and all hospitalized children had lower respiratory tract infections. A pediatric patient died from complications associated with hMPV A2a infection. hMPV has been reported as a respiratory pathogen in all age groups. No correlation was observed between viral subtype and disease severity in the samples of this study