Human metapneumovirus in infants and young children in Thailand with lower respiratory tract infections; molecular characteristics and clinical presentations

SummaryHuman metapneumovirus (hMPV) is a recently identified Paramyxovirus. The clinical features and molecular characteristics of hMPV in Asian populations have so far remained obscure.ObjectiveThe present study was designed to investigate the prevalence of hMPV in infants and young children presented with acute lower respiratory tract infection (ALRI) and to identify the molecular characteristics and clinical presentations.MethodsThere were 236 nasopharyngeal secretions (NPs) collected from infants and children presented with ALRI at King Chulalongkorn Memorial hospital between March 2001 and September 2003. Reverse transcriptase-polymerase chain reaction (RT-PCR) applying specific primers was done to identify hMPV and hRSV. Phylogenetic analysis of hMPV N, F and L genes was also performed.ResultsOf the 220 (236) infants and young children tested, positive results were found in 12 specimens (5.4%). The mean age of children with hMPV infections was 22±11 months. They mostly presented with fever with cough (100%) and upper respiratory tract symptoms (10/12, 83%). Eleven of twelve infants (92%) were hospitalized. Additionally, phylogenetic analysis identified two distinct lineages of hMPV.ConclusionOur results demonstrated the prevalence, molecular characterization and clinical spectrum of hMPV infection in infants and young children presented with lower respiratory tract infections in Thailand.