Timothy Ray Brown, widely known in research circles as the Berlin patient, was cured of his HIV infection by bone marrow transplants. Now scientists are trying to make sense of the traces of HIV they've found in some cells of his body. Richard Knox/NPR hide caption

itoggle caption Richard Knox/NPR

A mother and child wait to receive treatment at the HIV clinic in Nyagasambu, Rwanda, in Feb. 2008. The clinic was built by the Washington-based Elizabeth Glaser Pediatric AIDS Foundation with a grant from the PEPFAR program. Shashank Bengali/MCT/Landov hide caption

itoggle caption Shashank Bengali/MCT/Landov

Participants carry a rainbow flag during a gay, lesbian, bisexual and transgender parade in Mumbai, India. Rajanish Kakade/AP hide caption

itoggle caption Rajanish Kakade/AP

Gilead Sciences' Truvada is a step closer to being approved as a way to prevent HIV infection. Paul Sakuma/AP hide caption

itoggle caption Paul Sakuma/AP

A health worker injects a woman with a shot of Depo Provera, a quarterly contraceptive injection, at a health clinic in Busia, Uganda, in 2009. MCT/MCT via Getty Images hide caption

itoggle caption MCT/MCT via Getty Images

Many over-the-counter contraceptives contain a spermicide known as nonoxynol-9. Gretchen Cuda Kroen/For NPR hide caption

itoggle caption Gretchen Cuda Kroen/For NPR

Eric Goosby, United States Global AIDS coordinator, says field testing is necessary and urgent to determine if HIV testing-and-treating services are feasible. Brendan Hoffman/Getty Images hide caption

itoggle caption Brendan Hoffman/Getty Images

President Obama marked World AIDS Day Thursday by announcing plans to boost U.S. efforts to fight AIDS at home and abroad. Evan Vucci/AP hide caption

itoggle caption Evan Vucci/AP

The latest numbers from CDC show that only 28 percent of the nation's 1.2 million HIV-infected people are getting effective antiviral treatment; effective treatment rates are lowest among African-American men. Robyn Beck/AFP/Getty Images hide caption

itoggle caption Robyn Beck/AFP/Getty Images