Adolescents view it as less threatening than in the past, experts say.

On the eve of World AIDS Day, HealthDay reports the number of newly infected teens and young adults is on the rise. The number of new cases of HIV infection diagnosed among 15-to-19-year-olds in the U.S. rose 20 percent in just four years, according to data from the U.S. Centers for Disease Control and Prevention.

What's the reason for the sudden spike? Since HIV patients are now kept healthy by powerful drug cocktails, most teens view HIV as less of a threat. Marsha Chono-Helsley, executive director of REACH LA, a Los Angeles-based nonprofit that helps disadvantaged youth understand and defend against threats like poverty, drug abuse and HIV told HeathDay: "They're in this age group that feels they are invincible—that it's never going to happen to them. Yes, they're getting all these messages from public schools on HIV and AIDS, but they've never actually seen what HIV has done, up close and personal."

So what's a Mom to do, short of forcing her kid to watch Philadelphia? Experts say talking your teens about protecting themselves is key. A recent study conducted by the San Francisco AIDS Foundation found that adolescents want to talk with their parents about sexual risk-taking and HIV but many find it difficult to do so. Speak up, Moms, and open the lines of communication.