By Sheilah Downey - sheilahd at foodconsumer dot org

Ferrets exposed to three different viruses, including the H1N1 type, were twice as likely to get the swine flu than other strains, according to researchers a the University of Maryland.

The study suggests that the swine flu virus will not mutate into a virulent, or "superbug" form, but that it will prevail over other strains.

"The H1N1 pandemic virus has a clear biological advantage over the two main seasonal flu strains," said the study's lead author Dr. Daniel Perez, "and all the makings of a virus fully adapted to humans."

In what scientists think is the first study to examine how the pandemic virus interacts with other flu viruses, researchers also found that the H1N1 type established infections deeper in the ferret's respiratory system, including the lungs.

Researchers said the virus is behaving as most novel viruses behave in the flu world.

"I'm not surprised to find that the pandemic virus is more infectious," said the study's leader Dr. Daniel Perez, "simply because it's new, so hosts haven't had a chance to build immunity yet. Meanwhile, the older strains encounter resistance from hosts' immunity to them."

Some of the ferrets in the study who were infected with the H1N1 and more familiar seasonal strains, such as the H3N2, developed respiratory problems and intestinal illness as well, said researchers.

Perez said the findings will prompt additional research to see if the co-infection with multiple symptoms might account for some deaths from the swine flu.

While the study's findings show the importance of vaccinations against the swine flu, they are also a warning sign of its power and ability to spread, said Perez.

"The findings of this study are preliminary," he said, "but the far greater communicability of the pandemic virus serves as a clearly blinking warning light."