NEW YORK  - The World Health Organization has endorsed using HIV medicines among people who do not have the infection but are at high risk of getting it, and suggested that poor and wealthy countries alike set up pilot projects to better understand the benefits.

The United Nations agency made its suggestion on Friday, four days after US regulators approved use of Gilead Sciences Inc's Truvada for people who are not infected but may engage in sexual activity with HIV-positive partners. The concept is known as pre-exposure prophylaxis (PrEP).

Truvada, which combines the anti-HIV drugs tenofovir and emtricitabine in one pill, is widely used to treat people already infected with the virus that causes AIDS. The medicine, which costs almost $14,000 a year in the United States, is the first treatment also approved for prevention.

"WHO is encouraging countries wishing to introduce PrEP to first establish small projects to help public health workers to better understand and realize its potential benefits," the agency said in a statement. It said appropriate HIV medicines should be given to those at high risk of infection.

"These could include men or transgender women who have sex with men," the group said.

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