Each winter, strains of influenza A virus infect North Americans, causing an average of 36,000 deaths. Now, researchers say the virus comes from a viral reservoir somewhere in the tropics, settling a key debate on the source of each season's infection.

Outbreaks of the most common type of influenza virus, A (H3N2), are seeded by viruses that originate in East and Southeast Asia and migrate around the world, new research has found. This discovery may help to further improve flu vaccines and make the evolution of the virus more predictable.

Manipulating a previously identified protein may be the key to developing an effective H5N1 influenza A virus vaccine say researchers from the University of Wisconsin-Madison and the University of Tokyo. They report their findings in the March 2008 issue of the Journal of Virology.

The exchange of genetic material between two closely related strains of the influenza A virus may have caused the 1947 and 1951 human flu epidemics, according to biologists. The findings could help explain why some strains cause major pandemics and others lead to seasonal epidemics.

Emerging subtypes of influenza A virus hold the potential to initiate a world-wide epidemic in the next few years, according to World Health Organization officials. However, almost all type A influenza viral strains have become resistant to amantadine and rimantadine, two drugs that make up one of only two classes used to treat the flu.

The influenza A virus does not lie dormant during summer but migrates globally and mixes with other viral strains before returning to the Northern Hemisphere as a genetically different virus, according to biologists who say the finding settles a key debate on what the virus does during the summer off-season when it is not infecting people.

The influenza A virus does not lie dormant during summer but migrates globally and mixes with other viral strains before returning to the Northern Hemisphere as a genetically different virus, according to biologists who say the finding settles a key debate on what the virus does during the summer off season when it is not infecting people.

Researchers have determined that copper surfaces are significantly better than stainless steel at protecting against influenza A exposure. They report their findings in the April 2007 issue of the journal Applied and Environmental Microbiology.