Human metapneumovirus (HMPV) causes respiratory tract infection, especially in children. It was discovered in 2001 in the Netherlands. Similar to respiratory syncytial virus (RSV), HMPV is a member of the Paramyxoviridae family of viruses and has an RNA genome that encodes eight viral proteins. The virus has a lipid envelope that contains viral glycoproteins that are involved in entry of the virus into cells and fusion of the viral envelope with cell membranes. There are two main genetic lineages termed subtype A and B, each of which has two subgroups.
HMPV is a relatively common virus infection that often resembles the common cold; however, symptoms indicative of more severe HMPV infections may occur in high-risk patients such as infants, the elderly and those who are chronically ill. Most infections occur from October through April.
