title: Highly lethal H5N1 influenza virus in asia: Genesis and options for control.
abstract: Extract: Unprecedented animal epidemics of avian influenza viruses of the H5N1 subtype have been reported in Asia in 2004. These outbreaks resulted in the destruction of hundreds of millions of poultry. Of the 44 persons in Asia infected with H5N1 viruses, 32 died (20 in Vietnam and 12 in Thailand). It is impossible to predict whether H5 subtype viruses will acquire the ability to spread among humans and cause a new pandemic. The highly pathogenic Z genotype of H5N1 is now endemic in southeastern Asia and will continue to threaten veterinary and human public health. Influenza A viruses belong to the Orthomyxoviridae family and can be divided into 15 hemagglutinin (HA) and 9 neuraminidase (NA) subtypes on the basis of antigenic and sequence differences in these surface glycoproteins (proteins with sugar groups attached). In wild aquatic birds, influenza's natural hosts, the viruses cause no disease. Periodically, influenza viruses are transmitted to other hosts and cause transient infections and occasional deaths. Less frequently, influenza viruses are transmitted to other species and become adapted to the new hosts. Thus permanent lineages of influenza A viruses are established in humans, swine, horses, and domestic poultry.
authors: Division of Virology, Department of Infectious Diseases, St. Jude Children's Research Hospital, 332 North Lauderdale Street, Memphis, TN 38105, USA.
authors: Aleksandr S
authors: AS
authors: Lipatov
authors: Robert G
authors: RG
authors: Webster