Friday is a red-ribbon day, when public health officials want you to do more than reflect on HIV, they want you to get tested for the virus that causes AIDS.

National HIV Testing Day is one of nine annual HIV awareness days, which include days dedicated to different races and to developing an HIV vaccine.

"People can be walking around and positive and not really know they are," said Virginia King, director of prevention services at Lowcountry AIDS Services. "They put themselves at risk for the virus to impact their lives to a great degree. And they potentially put others at risk."

An estimated 250,000 people in the United States have HIV and are not aware of it, according to the U.S. Department of Health and Human Services. About 15,000 of those people are estimated to live in South Carolina, the state Department of Health and Environmental Control said.

The Human Immunodeficiency Virus is spread through sexual contact, sharing needles and can also be transmitted from mothers to babies during pregnancy and breastfeeding.

The virus affects the body's immune system; symptoms, including swollen lymph glands, fatigue and fever, can take years to develop.

"Getting people tested is the first step in linking infected people to appropriate care, treatment and prevention services," said Barbara Charles, DHEC's HIV counseling and testing program coordinator.

HIV remains a major public health threat, according to the Centers for Disease Control and Prevention. The impact is severe in the black and Latino community and among gay and bisexual men of all races, said Kevin Fenton, director of the National Center for HIV/AIDS.

Knowing your HIV status is important, especially if you've never had a test before, King said. People are scared to get tested because of the stigma still associated with the virus, she said.

But people with the virus are living longer. "HIV's becoming a chronic disease that requires total adherence to medication and good health," King said.