Sahya Idriss, a service provider at the health clinic in Minjibir, carries a vial of the polio vaccine. David Gilkey/NPR hide caption

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During the peak of the polio epidemic in the U.S., some hospital wards even had large, room-like iron lungs where multiple children lived. Courtesy of Boston Children's Hospital Archive hide caption

itoggle caption Courtesy of Boston Children's Hospital Archive

Women and their children wait for medication and instructions on how to use it at the clinic in Dareta, Nigeria. Treating children with high levels of lead is a painstaking process that works only if their environment at home is free from lead. David Gilkey/NPR hide caption

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Women and their children wait for medication and instructions on how to use it at the clinic in Dareta, Nigeria. Treating children with high levels of lead is a painstaking process that works only if their environment at home is free from lead. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

The Durban Children's hospital opened in 1931, as a facility for all races, but tensions during the apartheid era forced it to close in the 1980s. Courtesy of KwaZulu-Natal Children's Hospital hide caption

itoggle caption Courtesy of KwaZulu-Natal Children's Hospital

Doreen Ramogola-Masire, an obstetrician-gynecologist in Botswana, hopes that a simple, quick screen for cervical cancer with vinegar will catch the disease early and save women's lives. Jason Beaubien/NPR hide caption

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A doctor examines chest X-rays at a tuberculosis clinic in Gugulethu, Cape Town, South Africa in late 2007. The number of TB cases that don't respond to both first- and second-line medications is rising worldwide. Karin Schermbrucker /AP hide caption

itoggle caption Karin Schermbrucker /AP

A mobile clinic set up to test students for HIV is parked near Madwaleni High School in Mtubatuba, KwaZulu-Natal, South Africa on March 8, 2011. Parts of the South African province have HIV rates that are more than twice the national average. Stephane de Sakutin/AFP/Getty Images hide caption

itoggle caption Stephane de Sakutin/AFP/Getty Images

Health care workers in South Africa speak to residents during a door-to-door AIDS awareness campaign, part of a series of prevention efforts that has helped lower the country's HIV infection rate. Mujahid Safodien /Reuters /Landov hide caption

itoggle caption Mujahid Safodien /Reuters /Landov

Anti-AIDS posters hang in the Eshowe public health clinic in South Africa's Kwazulu-Natal province. Clinicians there are hoping to slow the spread of HIV by getting more people treatment. Jason Beaubien /NPR hide caption

itoggle caption Jason Beaubien /NPR

Drag queens at an outdoor restaurant in Copacabana incorporate safe sex messages into a show of lip-synced songs and risque jokes. Jason Beaubien/NPR hide caption

itoggle caption Jason Beaubien/NPR

Longtime AIDS activist Dr. Ashraf Grimwood says South Africa has made huge strides in confronting HIV. But he worries that giving anti-retroviral drugs to healthy people could have negative consequences in the long term. Jason Beaubien/NPR hide caption

itoggle caption Jason Beaubien/NPR