engleski

Human metapneumovirus infection in Croatia

Acute respiratory tract infections (ARTIs) are the major cause of morbidity and mortality in children worldwide. Many viruses are responsible for ARTIs in children, including human metapneumovirus (HMPV), the virus that was first isolated by van den Hoogen et al. in 2001. The signs and symptoms of HMPV infection in infants resemble those induced by respiratory syncytial virus (RSV) infection. HMPV infection has been mainly associated with bronchiolitis, pneumonitis, asthma exacerbation and upper respiratory tract infections including acute otitis media. Several seroprevalence surveys indicated that virtually all children are infected by 5-10 years of age. In order to asses seroprevalence of HMPV in Croatia, a total of 137 serum specimens from Croatian people aged from 6 days to 51 years without respiratory symptoms were collected. Sera were examined using an indirect immunofluorescent assay. HMPV overall seropositivity rate of the studied samples was 77.4% (106/137). The seropositivity rate increased from 18.7% in children aged 6 months to 1 year to 100% in people over 20 years of age. Moreover, to determine the incidence of HMPV infection in hospitalized children with ARTI in the winter season 2005/2006 nasopharyngeal secretions (NPSs) were collected from 402 inpatients up to 5 years of age. NPSs were tested by real time RT-PCR assay targeting the nucleoprotein (N) gene of HMPV. NPSs were also tested for RSV, influenza viruses, parainfluenza viruses (types1-3) and adenoviruses by direct immunofluorescence assay. HMPV was detected in 33 (8.2%), RSV in 101 (25.1%), adenoviruses in 41 (10.2%), parainfluenza viruses types1-3 in 24 patients (6.0%) and influenza viruses in 3 (0.7%) patients. In 3 HMPV positive patients other viral pathogen (1- parainfluenza virus type 3, 1- RSV, 1- adenovirus) was also detected. The peak incidence of HMPV infection was detected in January (18/33). No difference was noted between HMPV infected children and children infected with other viruses regarding to the sex. Children infected with adenovirus were significantly older than children infected with other viruses (HMPV, RSV and parainfluenca viruses). The majority of the infections caused by HMPV (69.7%) children presented with lower respiratory tract infections (LRTI). Comparative analysis of the clinical presentation of HMPV and RSV infected children revealed no significant differences between those two groups, although pneumonia tended to be more frequent in HMPV infected children. To perform the phylogenetic study, partial nucleotide sequences were obtained for HMPV fusion (F) gene of 30 HMPV positive samples. Phylogenetic analysis showed the circulation of two main genetic lineages (A and B), with B lineages being prevalent. It also showed the existence of two sublineages within the group B (B1 and B2) and three subclusters within lineage A (A1, A2a and A2b).

human metapneumovirus ; infection

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