Some of the animals who were infected with both the new virus and one of the more familiar seasonal viruses (H3N2) developed not only respiratory symptoms, but intestinal illness as well. Perez and his team call for additional research to see whether this kind of co-infection and multiple symptoms may account for some of the deaths attributed to the new virus.

Among other research findings, the pandemic virus successfully established infections deeper in the ferret's respiratory system, including the lungs. The H1 and H3 seasonal viruses remained in the nasal passages.

"Our findings underscore the need for vaccinating against the pandemic flu virus this season," Perez concludes. "The findings of this study are preliminary, but the far greater communicability of the pandemic virus is a clearly blinking warning light."

Perez and his team used samples of the H1N1 pandemic variety from last April's initial outbreak of the so-called swine flu.

Source: University of Maryland