The bar chart tells all: That's how eighth-graders at Bakgatle Community Junior Secondary School in Botswana can compare the HIV infection rate of older men and of teenage boys. Don Boroughs for NPR hide caption

itoggle caption Don Boroughs for NPR

In a study in Lesotho, the prospect of earning a cash prize in a lottery motivated young people to practice safe sex. iStockphoto hide caption

itoggle caption iStockphoto

Austin, Indiana's needle exchange program is open for business this week, but health workers worry the program will be tough to quickly replicate in other counties. Darron Cummings/AP hide caption

itoggle caption Darron Cummings/AP

Volunteer Patrick Pezzati searches yards in Turners Falls, Mass., for discarded heroin needles. Karen Brown/WFCR hide caption

itoggle caption Karen Brown/WFCR

In Philadelphia, some drug users are selling clean needles from needle exchange programs on the street. Researchers say the black market isn't necessarily a bad thing. ImageZoo/Corbis hide caption

itoggle caption ImageZoo/Corbis

Adebisi Alimi, an actor-turned-activist, was the first person ever to come out as gay on Nigerian television. He now shares his story when he speaks up for the rights of the LGBT community. Claire Eggers/NPR hide caption

itoggle caption Claire Eggers/NPR

Doug Neville (left) and Ryan Johnson have been friends for three decades. They met shortly before Neville found out he was HIV-positive. StoryCorps hide caption

itoggle caption StoryCorps

Ruth Coker Burks with her friend Paul Wineland. Wineland's partner was one of many AIDS patients Coker Burks has cared for over the past three decades. StoryCorps hide caption

itoggle caption StoryCorps
Lee Woodgate/Ikon Images/Corbis

Several countries, including Australia, Japan and Great Britain, already encourage blood donations from some gay men. Kevin Curtis/Getty Images/Science Photo Library hide caption

itoggle caption Kevin Curtis/Getty Images/Science Photo Library

Sizwe Nzima, right, and one of his six employees deliver medicines to patients in a Cape Town neighborhood. Anders Kelto for NPR hide caption

itoggle caption Anders Kelto for NPR

South Africa Health Minister Aaron Motsoaledi has no patience for people who abuse their health and expect the government to fix things. Alexander Joe/AFP/Getty Images hide caption

itoggle caption Alexander Joe/AFP/Getty Images

Do you know what the deadliest disease is? Hint: It's not Ebola (viral particles seen here in a digitally colorized microscopic image, at top right, along with similar depictions of other contagious diseases) NPR Composite/CDC hide caption

itoggle caption NPR Composite/CDC

Peter Piot was one of the co-discoverers of the Ebola virus in 1976. "I never thought we would see such a devastating and vast epidemic," he says. Leon Neal/AFP/Getty Images hide caption

itoggle caption Leon Neal/AFP/Getty Images