PART ONE:
Bill Gates is pumping $800 million a year into his global health initiative -- nearly matching the entire World Health Organization budget. Gates' immunization efforts have saved hundreds of thousands of lives. They are also controversial.

Also today:
- Bill and Melinda want a better world for their kids
- Disease and despair in a Delhi slum

Left: Bill Gates holds a child during a recent visit to Mozambique. The Gates Foundation now spends nearly as much on global health each year as the World Health Organization.

PART TWO:
Gates-funded public health projects in India and Cambodia seem similar. Both aim to protect some of the world's poorest children against disease. But the results to date couldn't be more different.
- Japanese encephalitis takes a toll
- Polio still a threat in India

PART THREE:
Move over, Geneva, New York and Atlanta. The new epicenter for global health strategy, science and spending may be Seattle, as Gates' seed money stimulates the region's fertile research landscape.
- PATH's lifesaving gizmos
- 'Market failure' costing lives