WASHINGTON--The U.S. Food and Drug Administration Monday approved a Gilead Sciences Inc. (GILD) HIV drug for use in certain healthy people to help prevent them from contracting the virus that causes AIDS. Truvada was previously approved for use in combination with other drugs to treat HIV. The new approval will allow the drug to be used in people who are considered at high risk of becoming infected with HIV, such as those people have an HIV-infected partner. The FDA said Truvada, a pill taken daily, is to be used in combination with safe-sex practices, such as condom use, to cut the risk of sexually acquired HIV infection in adults. The agency said doctors need to test patients to make sure they are HIV-negative before prescribing Truvada as a prevention tool as well as do follow-up testing every three months. The use of Truvada alone in a person who might become infected with HIV won't treat the virus effectively. "Today's approval marks an important milestone in our fight against HIV," said FDA Commissioner Margaret A. Hamburg in a statement. "Every year, about 50,000 U.S. adults and adolescents are diagnosed with HIV infection, despite the availability of prevention methods and strategies to educate, test, and care for people living with the disease," Dr. Hamburg said.