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.
HMPV is readily spread from contact with respiratory secretions from infected individuals or contaminated surfaces and objects.
There is no vaccine available for HMPV. Prevention of HMPV infection depends on good hygienic methods to reduce the spread of the virus.
Clinicians are not able to accurately diagnose HMPV infection based on signs and symptoms alone. There are many other viruses that infect the respiratory tract with a large overlap of symptoms among these infections. Diagnostic tests performed on specimens taken from the respiratory tract provide a useful aid to the diagnosis of HMPV. The direct fluorescent antibody method allows detection of the virus within two to three hours but is labor intensive and requires considerable experience. Molecular methods such as reverse transcription polymerase chain reaction-based tests are the most accurate methods to detect HMPV.
Management of an HMPV infection is generally focused on symptomatic therapy. When an HMPV infection becomes more serious and progresses to bronchiolitis, patient management goals are to relieve respiratory distress, alleviate airway obstruction and improve oxygen levels. It is important to normalize body temperature and maintain proper hydration.
