The number of adolescents who have died from AIDS has tripled in the past 15 years, and the disease is the second-leading cause of death in the age 10-19 population across the globe.

That’s according to data released Friday by the United Nation’s Children’s Fund, which added that the disease is the top killer for adolescents who are living in Africa. The organization, known more commonly as UNICEF, said adolescents are the only group that has not seen a drop in death rates in the past 15 years despite advances in disease prevention and treatment.

UNICEF said most of its data indicates most of the adolescents who are dying were infected with the disease when they were infants, when the treatments that help prevent infected pregnant mothers from passing the disease onto their children were not as common as they are today.

The UNICEF data showed that about 1.3 million children have been spared from the disease since 2000, largely thanks to improvements in mother-to-child transmission prevention. It said 60 percent of pregnant and breastfeeding women get medicine to prevent AIDS from spreading.

Despite those advances, the organization noted some shortfalls for the adolescent age group.

UNICEF said only one-third of the 2.6 million children under 15 who are living with AIDS are treated for the infection. It also announced that only 11 percent of 15-to-19-year-olds are tested for the disease in sub-Saharan Africa, where the infection rate is the most prevalent.

The disease also remains a problem for those who are not born with it.

UNICEF’s data showed that 26 new 15-to-19-year-olds become infected with the disease every hour, and 40 percent of those occur outside sub-Saharan Africa. The Associated Press reported that the United States, India, Indonesia and Brazil all had a “worrying rate” of teen infection.

UNICEF called for worldwide solutions that provide early diagnosis for babies (less than half of children are tested before they are two months old, and AIDS progresses quickly in newborns). It also seeks to keep women, children and adolescents treated and improve sex education.