While the global push to eradicate HIV may have saved over a million babies, AIDS is now the leading cause of death for African teenagers and the second most common killer for adolescents across the globe, the United Nations’ agency for children said on Friday.

Children born with the virus were dying in their teens because there was not enough treatment aimed at adolescents. Only a third of the 2.6 million children infected with HIV were on treatment.Teenagers born without the disease are also vulnerable, and infections rates among those aged 15 to 19 now add up to 26 new infections every hour with 70 percent of those infected girls. Women are biologically more susceptible to HIV infection, but behind that statistic are social factors like illiteracy and child marriage.

While 60 percent of adolescent infections occur in sub-Saharan Africa — with South Africa leading, followed by Nigeria — countries like the United States, India, Indonesia and Brazil also showed a worrying rate of infection among teenagers.

The report says that half of the world’s HIV-positive teens between the ages of 15 and 19  live in South Africa, Nigeria, Kenya, Mozambique, Tanzania and India. And that only 1 in 3 of the 2.6 million children under the age of 15 living with HIV are on treatment. The UN presented this and other disturbing data this week in Johannesburg as part of their global statistical update on AIDS among children. The study also found that globally, less than half of infants are tested for HIV.