Three decades into the AIDS epidemic, the virus is killing the world's teens at a shockingly high rate.The number of adolescents dying of AIDS-related complications has tripled since 2000, according to figures released by UNICEF ahead of World AIDS Day . The virus is the second-largest killer of 10-to-19-year-olds worldwide.In Africa, the situation is especially dire. AIDS is the number-one cause of death for adolescents there, the UNICEF report, Statistical Update on Children, Adolescents and AIDS, found.These statistics are at the top of mind as people around the globe mark World AIDS Day on December 1, a yearly international effort to raise awareness about HIV and AIDS.More than 36 million people are living with HIV or AIDS worldwide. Overall, infection and death rates have fallen across the globe. But the death rate among adolescents is a sad exception to that trend.Most of the teens dying today became infected as infants, often from mothers who didn't have access to antiretroviral medicines that can help lower the chance of transmission at birth. While major strides have been made on that front — UNICEF estimates that anti-retroviral treatment for pregnant women has helped save 1.3 million children from contracting the virus — there's major work to be done in curbing new cases among teens.An estimated 26 new infections among adolescents age 15 to 19 occur every hour. In sub-Saharan Africa, girls account for seven in 10 of those new diagnoses.Expanding HIV testing and treatment for those children and teens who are infected remains a big challenge. Just one-third of the 2.6 million children living with HIV today have access to treatment, UNICEF found.“The gains we have made on preventing mother-to-child transmission are laudable, and to be celebrated,” Craig McClure, head of UNICEF’s global HIV/AIDS program, said in a statement . “But immediate investments are needed to get life-saving treatment to children and adolescents who are infected."For more about how AIDS impacts the world's children today, visit this link