A doctor takes an HIV test from an athlete during the 18th National Sports Festival in Lagos, Nigeria, last December. Sunday Alamba/AP hide caption

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Latinos and African-Americans are more active on social media. Could that help promote HIV testing among minorities? Brendan Smialowski/Getty Images hide caption

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A prostitute in Johannesburg waits for a client on a street corner. An estimated two-thirds of sex workers in South Africa are HIV positive. Yoav Lemmer/AFP/Getty Images hide caption

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A nurse takes a blood sample from Nkosi Minenhle, 15, in a mobile clinic set up to test students for HIV at Madwaleni High School in KwaZulu Natal, South Africa. Stephane de Sakutin/AFP/Getty Images hide caption

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A woman waits to get AIDS drugs on April 8 at a clinic in Ga-Rankuwa, South Africa, about 55 miles north of Johannesburg. New WHO guidelines say patients should start HIV treatment much earlier, before they become extremely sick. Stephane de Sakutin/AFP/Getty Images hide caption

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Women in Bangalore, India, make red ribbons at an HIV support center in November 2012. Manjunath Kiran/AFP/Getty Images hide caption

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The Centers for Disease Control and Prevention says doctors should prescribe Truvada, a once-a-day pill for HIV, to help prevent infections in IV drug users. Jeff Chiu/AP hide caption

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An electron micrograph of HIV particles infecting a human T cell. French researchers say they've found 14 patients with so little HIV virus in their blood that the patients have gone into "long-term remission." National Institute of Allergy and Infectious Diseases hide caption

itoggle caption National Institute of Allergy and Infectious Diseases

By taking antiretroviral drugs during pregnancy, this Tanzanian mother lowered the risk of passing HIV to her daughter. Siegfried Modola/AFP/Getty Images hide caption

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HIV drugs not only can keep patients healthy but also can stop the sexual transmission of the virus. Here an HIV-positive mother picks up medications at a hospital outside Johannesburg, South Africa. Alexander Joe/AFP/Getty Images hide caption

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