Scientists infected both species in laboratory experiments and showed that animals could pass the virus to others, researchers reported in today?s issue of the journal Nature. The cats remained healthy, but some of the ferrets got sick. While the findings suggest that the animals could play a role in spreading the virus, there is no evidence to date that the animals can pass the virus to people, the researchers stressed.

?You cannot completely exclude that possibility. If you have close contact, it theoretically could be transmitted,? Albert D.M.E. Osterhaus of the Erasmus Medical Center in Rotterdam, who led the research, said in a telephone interview. But it is unlikely ?from an epidemiological point of view? that cats would play a significant role in spreading the disease. Cats and ferrets appear to excrete the virus for only a relatively short time, he said.

?It?s much more likely you would get infected from other people,? Osterhaus said. Nevertheless, because of the pets? large numbers and close contact with humans in many places, the findings indicate that cats and ferrets ?could serve as an ideal bridge between the unknown reservoir for the virus in the wild,? said Klaus Stohr, a SARS expert at the World Health Organization in Geneva. ?That?s concerning.?

Severe acute respiratory syndrome (SARS), which emerged in southern China in November 2002, is caused by a previously unknown member of the corona family of viruses. The virus has been found in ferret badgers, masked palm civets and raccoon dogs in southern China, suggesting that it jumped from animals to people. But it remains unclear whether those three species are the primary carriers or whether some other, yet unidentified species is the primary carrier.