A second type of AIDS virus has apparently spread from Africa to the Americas, an ominous development that may complicate the already daunting epidemic, researchers reported.

Researchers said Wednesday they found a small but significant percentage of high-risk individuals in Brazil were infected with HIV-2, a cousin of the human immunodeficiency virus or HIV, which causes most AIDS cases. HIV-2 also has been shown to cause the deadly disease."HIV-2 has spread to the Americas," said Dr. David Ho, director of the AIDS virology laboratory at the Cedars-Sinai Medical Center in Los Angeles who helped conduct the new research. "It's not a pathogen to be taken lightly."

It is unclear how common the virus is elsewhere in the region, and the spread of the virus does not pose any new problems immediately.