In Indonesia, fresh approaches to illegal drug use and the sex industry are helping to reduce the spread of HIV. Now addicts can get access to methadone programs and clean needles, and sex workers are being tought about prevention methods by former colleagues. 

More than half a million women die every year from complications of pregnancy and childbirth, and almost all of these could be avoided with access to professional health care. Which is why Australia is helping to train the next generation of midwives and providing specialist surgical services and training in East Timor.

HIV is a growing problem among young people in Malaysia, which means more effective ways are needed to teach teenagers about the dangers of the disease. In one innovative UNICEF-supported initiative, exchange students are talking to young Malaysians about prevention in settings far from traditional classrooms. 

Alleviating poverty is more guesswork than science, and lack of data on aid's impact raises questions about how to provide it. But Clark Medal-winner Esther Duflo says it's possible to know which development efforts help and which hurt—by testing solutions with randomized trials. 

Nathan Myhrvold and team's latest inventions—as brilliant as they are bold—remind us that the world needs wild creativity to tackle big problems like malaria. And just as that idea sinks in, he rolls out a live demo of a new, mosquito-zapping gizmo you have to see to believe. 

Sampat Pal is a campaigner with a mission: to ensure that those born into the lowest caste have an education, avoid child marriages, and earn a decent wage. But, while Mahatma Gandhi famously preached non-violence, Pal believes that India's long history of patriarchy, abuse, and corruption demands a new style of justice.

The battle against HIV presents unique challenges in different cultures around the world. In India, Dr. Suniti Solomon and her team at the YRG Centre for AIDS Research and Education are working hard to change attitudes and slow the spread of the disease.

Virus hunter Nathan Wolfe is outwitting the next pandemic by staying two steps ahead: discovering deadly new viruses where they first emerge (passing from animals to humans among poor subsistence hunters in Africa) before they claim millions of lives.

In the shantytowns of Cape Town, South Africa, the local healthcare system has been stretched to near breaking point by the impact of HIV. But volunteers from both the healthcare profession and the local community, are fighting back and giving hope to ordinary people.

Children in developing nations with curable health problems often die because of inadequate healthcare facilities and training. Surgeons of Hope is sending medical specialists to Nicaragua to help treat children and teach local personnel life-saving surgical procedures.

New water wells are being built in rural El Salvador that are safe from contamination by floodwater. Maintained by local people, they are impacting everything from public health to the ability of children to attend school—an example of how something as basic as clean water can be the basis of change for a whole community.