You are in: eMedicine Specialties > Infectious Diseases > MEDICAL TOPICS Human MetapneumovirusArticle Last Updated: Apr 19, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 8
  Author: Michael D Nissen, MBBS, BMedSc, FRACP, FRCPA, Associate Professor in Biomolecular, Biomedical Science & Health, Griffith University; Director of Infectious Diseases and Unit Head of Queensland Paediatric Infectious Laboratory, Sir Albert Sakzewski Viral Research Centre, Royal Children's Hospital Michael D Nissen is a member of the following medical societies: American Academy of Pediatrics, American Society for Microbiology, Pediatric Infectious Diseases Society, Royal Australasian College of Physicians, and Royal College of Pathologists of Australasia Coauthor(s): Theodorus P Sloots, PhD, Director, Sir Albert Sakzewski Virus Research Center, Queensland Pediatric Infectious Diseases Laboratory, Royal Children's Hospital and Health Service District; David Siebert, MBBS, FRCPA, Director of Virology, Department of Microbiology, Queensland Health Pathology Service, Royal Brisbane Hospitals Complex Editors: Douglas A Drevets, MD, Assistant Professor, Department of Medicine, Section of Infectious Disease, Oklahoma University Health Sciences Center; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; John W King, MD, Professor of Medicine, Section of Infectious Diseases, Louisiana State University Health Sciences Center; Director, Viral Therapeutics Clinics for Hepatitis; Consulting Staff, Department of Infectious Diseases, Overton Brook Veterans Affairs Medical Center; Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital; Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital Author and Editor Disclosure Synonyms and related keywords: human metapneumovirus, metapneumovirus, hMPV, human parainfluenza virus 1, HPIV-1, paramyxoviruses, Paramyxoviridae, human respiratory syncytial virus, hRSV, respiratory syncytial virus, RSV infection, avian pneumovirus, APV, turkey rhinotracheitis virus, TRTV, viral infection, viremia, respiratory disease, respiratory tract disease INTRODUCTIONSection 2 of 8
  BackgroundHuman metapneumovirus (hMPV) is a newly identified virus of the Paramyxoviridae family. It was first reported in June 2001 as a cause of respiratory tract disease in Dutch children (van den Hoogen, 2001). The clinical features of hMPV infection are indistinguishable from those caused by human respiratory syncytial virus (hRSV), the single most likely cause of lower respiratory tract infection in children worldwide. Subsequently, hMPV has been detected as a cause of respiratory tract disease in both children and adults worldwide. The recognition of this novel virus is an exciting development in the diagnosis and management of significant respiratory tract disease. PathophysiologyThe Paramyxoviridae family includes major human and animal pathogens. Surprisingly, the closest genetic relative of this novel virus is not hRSV, but avian pneumovirus (APV). APV, previously known as turkey rhinotracheitis virus, was formerly the sole member of the Metapneumovirus genus. hMPV is the first described mammalian species of Metapneumovirus. Like members of the Paramyxoviridae family, hMPV is a single-stranded RNA virus. Epidemiology: Studies regarding its epidemiology have been conducted by a number of researchers but are typically restricted to a limited number of patients or specimens collected during discrete seasonal intervals. A recent study in Queensland, Australia conducted over 4 years (2001-2004) determined an average annual incidence of hMPV of 7% in that population. This makes hMPV the second most frequently detected respiratory virus on an annual basis. Genotyping of the gene coding for the hMPV P protein showed that each of the 4 subtypes were present in the sample population. A change in dominant subtype occurred over the 4-year period. This confirms that hMPV is a significant pathogen in lower respiratory infection of children and is implicated in nosocomial spread of infection in hospital wards. FrequencyInternationalhMPV is considered ubiquitous throughout the world. This belief is based on the widespread detection of infection and the high prevalence of antibodies against the virus in all age groups. In their 2001 report, van den Hoogen and colleagues demonstrated that by age 10 years, all Dutch children were seropositive for the virus. Similar studies in Canada, Japan, Israel, and Australia have also confirmed the high seroprevalence of hMPV antibodies in the population, with greater than 98% of children positive by age 10 years. While only recently discovered, the virus has apparently caused human infection for at least 50 years. Sera collected from a Dutch population (aged 8-99 y) in 1958 were 100% positive for hMPV (van den Hoogen, 2001). Recent studies conducted in the Northern hemisphere showed an incidence of hMPV infection ranging from between 3.9% and 8.1%, with most infections occurring during winter and early spring. The exception to this was reported by Peiris et al in Hong Kong, who detected hMPV in 5.5% of samples collected over a 12-month period, with a peak of infection in spring and early summer. Incidence data for the Southern hemisphere are limited, with reports of 24% in Brazil, 7.4% in South Africa, and 3.8-7% in Australia. Mortality/MorbiditySimilar to hRSV infection, hMPV infection is an important cause of respiratory tract infection in children, particularly infants. In the original description of hMPV infection, 27 (96%) of the 28 cases mentioned were in children younger than 5 years, with 13 (46%) of these children being younger than 1 year. The true prevalence of hMPV disease is also not yet known. Most studies to date have concentrated on hospitalized children. In such cases, hMPV can be expected to be present in 15-20% of nasopharyngeal specimens, depending on the locale and season. Co-infection with other respiratory tract viruses, such as RSV and influenza virus, sometimes occur. Asymptomatic carriage is not thought to occur, based on the failure to detect the virus in 400 healthy Dutch children aged younger than 2 years (van den Hoogen, 2001). SexhMPV infection has no sexual predilection. AgePersons of all ages are involved; the initial acquisition of the infection occurs in children younger than 5 years. CLINICALSection 3 of 8
HistoryWhen first reported, the clinical manifestations of hMPV infection were similar to those described for hRSV (van den Hoogen, 2001). The spectrum of disease ranged from mild respiratory symptoms to severe cough, bronchiolitis, and pneumonia. High fever, myalgia, and vomiting were also commonly associated with hMPV infection. Some patients required hospital admission and mechanical ventilation.
DIFFERENTIALSSection 4 of 8
Adenoviruses Influenza Parainfluenza Virus Pharyngitis, Bacterial Pharyngitis, Viral Picornavirus-Overview Pneumonia, Viral WORKUPSection 5 of 8
Lab Studies
TREATMENTSection 6 of 8
Medical CareCurrently, no specific treatment is available for hMPV infection, other than symptomatic treatment or respiratory support when required. An in vitro study suggests a potential role for combination therapy with polyclonal immunoglobulin and ribavirin. Identification in health care settings is important because hMPV infection has been associated with nosocomial infections and prolonged hospital stays. FOLLOW-UPSection 7 of 8
Deterrence/Prevention:
Patient Education:
REFERENCESSection 8 of 8
Article Last Updated: Apr 19, 2006 |
