Helping stop mothers giving their babies HIV
14 October 2013 Last updated at 06:32 BST
Africa carries the biggest burden of HIV in the world, but the picture is improving through a concerted effort to prevent mother to infant infections.
A combination of drugs and education programmes means that only half as many HIV-positive mothers in Africa are now passing on the virus to their babies, compared to a decade ago.
The BBC's Anne Soy visited one such baby and his mother in Nairobi.