About one out of every four new HIV infections in the U.S., according to the Centers for Disease Control and Prevention (CDC), are diagnosed in people between 13 and 24. While this frightening statistic may already be sounding your alarm bells, additional information supplied by a new survey increases the decibels to a deafening level: A full 88 percent of American teens don’t think they’re at risk for getting HIV, and a third don't know the virus is sexually transmitted, while the number of undiagnosed HIV cases are thought to be highest among their ranks. In fact, the CDC estimates more than half of all undiagnosed HIV infections are occurring among people between the ages of 13 and 24 with the highest concentrations of HIV diagnoses located in Florida, South Carolina, and Louisiana.

“Within a few short years in the 1980s, HIV went from an unknown condition to an epidemic that was infecting more than 130,000 people annually,” write the authors of the National HIV/AIDS Strategy, a coordinated plan issued by the White House in 2010. Those earliest years of the epidemic were characterized by urgency and commitment to comprehending and ultimately curing the disease. Through diligent work, scientists learned how HIV attacks specific cells of the immune system, called T cells and over time, the virus can destroy so many of these cells that the body can’t fight off infections and disease. In the past decade, though, the sense of urgency has been lost. “Unless we take bold actions, we face a new era of rising infections, greater challenges in serving people living with HIV, and higher health care costs,” note the authors of the report.

Meanwhile, the new M.A.C. AIDS Fund U.S. Survey, which was conducted between May 22 and June 5, issues a similar alert. The survey found just two thirds of teens (71 percent) between the ages of 12 and 17 understand using a condom can help them avoid the disease. Yet, the latest CDC report paints a darker picture. Among the sexually active students nationwide, about 41 percent reported they did not use a condom during their most recent experience of sexual intercourse. The rates of infection continue to climb among those between the ages of 15 and 19, while being highest among those between the ages of 20 and 24.

Who are these diagnosed and undiagnosed teens? (Undiagnosed carriers are estimated to account for one in every five people with the virus.) Young gay and bisexual men make up most of the new HIV infections among the young, with African American gay and bisexual men being especially affected. Nearly 80 percent of all adolescent infections are to boys, with nine out of 10 adolescent HIV infections resulting from male-to-male sexual contact.

Yet of the adolescent girls who become infected, the exact same proportion — nine out of 10 — become infected from heterosexual contact. While all teens are clearly at risk, few understand everything they need to know. If you wish to talk to a teen about this issue, but don’t know how, go here.