The Michigan Organization on Adolescent Sexual Health is encouraging at-risk youth to recognize National HIV Testing Day by getting tested Thursday.

In Washtenaw County, youths between the ages of 13 and 24 make up 19 percent of all people diagnosed with HIV and those between the ages of 15 and 24 make up 38 percent.

HIV, short for human immunodeficiency virus, is the virus that causes AIDS.

What makes certain youths more at risk than others is a lack of available information on transmission as well as prevention, said Shelly Hoffman, executive director at MOASH.

"A lot of youth are at risk and it is especially those that live in urban areas who don't have access to HIV prevention information and resources," Hoffman said. "They are at a higher risk than those that have quality sexual education programs at their schools."

MOASH will focus on encouraging youth to get tested since they represent a large portion of those affected and are likely to engage in activities to put them at risk, according to a press release.

"Young people are getting infected at alarming rates and we want to draw attention to that," Hoffman said. "With all the information that exists, it's amazing that a lot of youth don't know how to prevent HIV — some don't even know how they get it. We need to make information available."

Among youth, transmission most commonly occurs from having unprotected sex and sharing needles with someone who has HIV.

The Michigan Department of Community Health reported in 2012 that 54 percent of Michigan seniors in high school reported having had intercourse. Fifteen percent of those who reported being sexually active said they had four or more sexual partners.

One in five people in the U.S. are living with HIV and don't know they are infected because there are often no symptoms, the press release said. For this reason, MOASH is encouraging routine HIV testing as a part of adolescent sexual health.

The Washtenaw County Public Health 2012 Annual Report reported a little more than a 30 percent decline in the number of people being tested in Washtenaw County during 2012.

The best way to encourage youths to get tested is to have encouragement come from their peers, Hoffman said.

"Youth learn a great deal from their peers," Hoffman said. "Peer education and encouragement from other peers is the best way to get the word out and have it actually stick. That and going to where they are. Sitting back and expecting them to come to us just doesn't work."

According to MOASH, several organizations across the state are holding National HIV Testing Day events, with some organizations offering free testing. HIV/AIDS Resource Center, or HARC, will be offering rapid testing, allowing individuals to get tested and find out their results in 20 minutes.

HARC will use their mobile outreach vehicle to offer the free and confidential testing, counseling and education about treatment and prevention on Thursday at the following times and locations:

• Noon to 2 p.m. at Maple Village Pharmacy, 325 N. Maple Road in Ann Arbor
• 2:30 to 4:30 p.m. at Walgreens, 2170 Washtenaw Ave., in Ypsilanti
• 5 to 8 p.m. at Harmony House Motel, 615 E. Michigan Ave., in Ypsilanti

Testing facilities and more information about MOASH and HARC can be found online.

Chelsea Hoedl is an intern reporter for AnnArbor.com. She can be reached at choedl@mlive.com.