French researchers have discovered in Africa a new strain of the virus that causes AIDS that is so different from other known strains that it easily escapes detection by standard blood screening tests. The new variant of HIV-1 does not currently threaten the safety of the blood supply or otherwise pose a significant public health threat since it is extremely rare. It was discovered in a 40-year-old Cameroonian woman who died of AIDS-related problems in 1995, and it has since been implicated in only three other cases of AIDS, all in Cameroon.