Pandemic influenza virus has its origins in avian influenza viruses. The highly pathogenic
avian influenza virus subtype H5N1 is already panzootic in poultry, with attendant economic …

Influenza A virus is a major public health threat, killing more than 30 000 per year in the USA
alone, sickening millions and inflicting substantial economic costs. Novel influenza virus …

Interspecies transmission of influenza A viruses circulating in wild aquatic birds occasionally
results in influenza outbreaks in mammals, including humans. To identify early changes in …

The origin of the H5N1 influenza viruses that killed six of eighteen infected humans in 1997
and were highly pathogenic in chickens has not been resolved. These H5N1 viruses …

Mammalian influenza viruses are descendants of avian strains that crossed the species
barrier and underwent further adaptation. Since 1997 in southeast Asia, H5N1 highly …

Pigs serve as major reservoirs of H1N1 and H3N2 influenza viruses which are endemic in
pig populations world-wide and are responsible for one of the most prevalent respiratory …

The “Spanish” influenza pandemic of 1918–19 caused acute illness in 25–30 percent of the
world's population and resulted in the death of up to an estimated 40 million people. Using …

Waterfowl are the natural reservoir of all influenza A viruses, which are usually
nonpathogenic in wild aquatic birds. However, in late 2002, outbreaks of highly pathogenic …

The transmission of H9N2 influenza viruses to humans and the realization that the A/Hong
Kong/156/97-like (H5N1)(abbreviated HK/156/97) genome complex may be present in …

Influenza pandemics and epidemics have apparently occurred since at least the Middle
Ages. When pandemics appear, 50% or more of an affected population can be infected in a …