(S (S (S (BASENP (NN AIDS)) (VP (VBZ is) (VP (VBN estimated) (S (VP (TO to) (VP (VB have) (VP (VP (VP (VBN killed) (BASENP (QP (NN 25) (NN million)) (NNS people))) (ADVP (RB worldwide))) (PP (IN since) (BASENP (NN 1981)))))))))) (CONJP (COMMA ,) (CC and)) (S (S (NP (QP (NP (RB between) (BASENP (NN 33) (CC and) (NN 46) (NN million))) (ADJP (JJR more)))) (VP (VBP are) (VP (VBN estimated) (S (VP (TO to) (VP (VB be) (VP (VBN infected) (PP (IN with) (BASENP (NN HIV)))))))))) (COMMA ,) (NP (NP (BASENP (QP (ADVP (RBR more) (IN than)) (NN half))) (PP (IN of) (BASENP (PRP them)))) (PP (IN in) (BASENP (NNP Sub-Saharan) (NNP Africa)))))) (PERIOD .))