CHEYENNE, Wyo. (AP) — The Wyoming Department of Health is encouraging people to take advantage of free HIV testing available at family planning clinics and public health offices throughout the state.

The Centers for Disease Control and Prevention estimates that 20 percent of the people who are positive for HIV don't know that they have it.

Rob Johnston is HIV prevention coordinator for the Wyoming Department of Health. He says the CDC reports that more than half of people between the ages of 18 and 64 have never been tested for the HIV virus.

Of those who test positive, Johnston said one third are tested too late to get the full benefit of treatment that could help to prevent or delay the development of AIDS.