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Bill Gates Sr. (L), former South African President Nelson Mandela and former U.S. President Jimmy Carter hold babies at the Zola clinic in the Soweto Township outside of Johannesburg, South Africa, March 7, 2002. The babies were born to mothers who have tested positive for HIV. Bill Gates Sr. is traveling in Africa with former President Carter on a trip for the Bill and Melinda Gates Foundation in an effort to focus attention on HIV and AIDS prevention. The foundation also is working to reduce the stigma that comes with a positive HIV test. (Photo by Jeff Christensen/WireImage)

Bill Gates Sr. (L), former South African President Nelson Mandela and former U.S. President Jimmy Carter hold babies at the Zola clinic in the Soweto Township outside of Johannesburg, South Africa, March 7, 2002. The babies were born to mothers who have tested positive for HIV. Bill Gates Sr. is traveling in Africa with former President Carter on a trip for the Bill and Melinda Gates Foundation in an effort to focus attention on HIV and AIDS prevention. The foundation also is working to reduce the stigma that comes with a positive HIV test. (Photo by Jeff Christensen/WireImage)