Kidney dysfunction Heart problems Although bird flu may kill more than half the people it infects, the number of fatalities is still low because so few people have had bird flu. Fewer than bird flu deaths have been reported to the World Health Organization since In contrast, the Centers for Disease Control and Prevention estimates that seasonal influenza is responsible for thousands of deaths each year in the United States alone. Prevention Bird flu vaccine The Food and Drug Administration has approved one vaccine to prevent infection with one strain of H5N1 bird flu virus.
Clade 2 viruses were first identified in bird isolates Bird flu ChinaIndonesiaJapanand South Korea before spreading westward to the Middle EastEuropeand Africa. The clade 2 viruses have been primarily responsible for human H5N1 infections that have occurred during late andaccording to WHO. Genetic analysis has identified six subclades of clade 2, three of which have a distinct geographic distribution and have been implicated in human infections: Before our project, GenBank contained only 5 other complete genomes from Europe for the — period, and it contained no whole genomes from the Middle East or northern Africa.
Our analysis showed several new findings. First, all European, Middle Eastern, and African samples fall into a clade that is distinct from other contemporary Asian clades, all of which share common ancestry with the original Hong Kong strain.
Phylogenetic trees built on each of the 8 segments show a consistent picture of 3 lineages, as illustrated by the HA tree shown in Figure 1. Two of the clades contain exclusively Vietnamese isolates; the smaller of these, with 5 isolates, we label V1; the larger clade, with 9 isolates, is V2.
The remaining 22 isolates all fall into a third, clearly distinct clade, labeled EMA, which comprises samples from Europe, the Middle East, and Africa.
Trees for the other 7 segments display a similar topology, with clades V1, V2, and EMA clearly separated in each case.
A stands for the genus of influenza AB or C. N1 stands for the first of several known types of the protein neuraminidase. The distinction concerns pathogenicity in poultry, not humans.
Normally, a highly pathogenic avian virus is not highly pathogenic to either humans or nonpoultry birds.
This current deadly strain of H5N1 is unusual in being deadly to so many species, including some, like domestic cats, never previously susceptible to any influenza virus. HA codes for hemagglutininan antigenic glycoprotein found on the surface of the influenza viruses and is responsible for binding the virus to the cell that is being infected.
NA codes for neuraminidasean antigenic glycosylated enzyme found on the surface of the influenza viruses. It facilitates the release of progeny viruses from infected cells.
HA and NA are also used as the basis for the naming of the different subtypes of influenza A viruses. This is where the H and N come from in H5N1. Influenza A viruses are significant for their potential for disease and death in humans and other animals.
Influenza A virus subtypes that have been confirmed in humans, in order of the number of known human pandemic deaths that they have caused, include: H1N1which caused the flu pandemic "Spanish flu" and currently is causing seasonal human flu and the flu pandemic " swine flu " H2N2which caused "Asian flu" H3N2which caused "Hong Kong flu" and currently causes seasonal human flu H5N1" bird flu "which is noted for having a strain Asian-lineage HPAI H5N1 that kills over half the humans it infects, infecting and killing species that were never known to suffer from influenza viruses before e.
In most cases, it causes minor sickness or no noticeable signs of disease in birds. It is not known to affect humans at all. The only concern about it is that it is possible for it to be transmitted to poultry and in poultry mutate into a highly pathogenic strain.
Therefore, USDA now tracks these detections in wild birds, backyard flocks, commercial flocks and live bird markets. The segmentation of its genome facilitates genetic recombination by segment reassortment in hosts infected with two different influenza viruses at the same time.
The ability of various influenza strains to show species-selectivity is largely due to variation in the hemagglutinin genes.
Genetic mutations in the hemagglutinin gene that cause single amino acid substitutions can significantly alter the ability of viral hemagglutinin proteins to bind to receptors on the surface of host cells. Such mutations in avian H5N1 viruses can change virus strains from being inefficient at infecting human cells to being as efficient in causing human infections as more common human influenza virus types.Bird flu viruses infect birds, including chickens, other poultry, and wild birds such as ducks.
Usually bird flu viruses only infect other birds.
It is rare for people to get infected with bird flu viruses, but it can happen. On March 5, , the United States Department of Agriculture reported that a lethal outbreak of avian flu had struck a poultry farm in Mississippi. The very next day that news was followed with confirmation that a poultry farm in southern Tennessee also had an infected flock with a more severe strain of avian flu.
A deadly new strain of bird flu threatens to become a worldwide pandemic, health officials warn. Britain’s deputy chief medical officer Jonathan Van-Tam says the strain, which has already killed. (aka bird flu, avian flu) is caused by a type of influenza virus that is hosted by birds, but may infect several species of mammals.
It was first identified in Italy . Bird flu hits French foie gras industry at busiest time of year Thousands of birds slaughtered and export ban extended as France is put on high alert following outbreak in south-west Published: 6.
Bird flu (avian influenza) is a disease caused by strains of influenza virus that primarily affects birds. In the late s, a new strain of bird flu arose that was remarkable for its ability to cause severe disease and death, especially in domesticated birds such as ducks, chickens, or turkeys.