Children sing the lullaby “Twinkle, Twinkle, Little Star” during class at the Hot Courses Primary School, in the Kenyan village of Nyumbani, which caters to children who lost their parents to HIV, and grandparents who lost their children to HIV, with the bookend generations taking care of one another. Saturday, Dec. 1, is World AIDS Day, and UNAIDS says that as of 2011, an estimated 23.5-million people living with HIV resided in sub-Saharan Africa, representing 69 per cent of the global HIV burden, with eastern and southern Africa the hardest-hit regions.Ben Curtis/The Associated Press