alexandra levine: the transmission rate for h.i.v.e united states from mother to infant is about 25 to 30%. we can lower it to 8% risk by use of anti-h.i.v. medicines given to the mother during pregnancy, given to the mother by vein during the entire time of the delivery, and then given to the infant for the first week of life or the first month of life. progress against the disease in many other parts of the world, is not as promising. it's decimating populations in parts of central africa, in parts of southeast asia, in parts of the indian subcontinent, and it's affecting whole generations of individuals. we know, for example, that there are probably about 25 to 30 million people in the world infected with h.i.v. this year, and that that number will continue to increase quite rapidly in the next few years, especially in those parts of the world where prevention efforts and treatment are very minimal. david bennett: the impact of h.i.v./aids in africa has been incredible. to lose the young people who are really the productive segment