The bus to Duke. Farmer considers it a privilege, not a deprivation, that when he was 12 his family took up a peripatetic residence in an old school bus. When the bus was wrecked in an accident, the family moved into a campground tent and then into a jury-rigged houseboat moored in the Gulf of Mexico. Still, says Farmer, his family bonds were loving and strong, and the high school senior class president won a full scholarship to Duke.

Inspired by the writings of Rudolf Virchow, a 19th-century German medical pioneer whom he discovered at Duke, and pushed by his own Roman Catholicism to help the poor, Farmer went to Haiti in 1983, planning to spend a year there. He stayed much longer. When he received his Harvard M.D. and Ph.D. degrees in 1990, the 31-year-old had treated more types of illness and injury than many doctors see over a career.

By the early 1990s, his Haitian clinic had become a well-equipped center, with trained community health agents serving 100,000 people around Cange. Farmer and his staff enjoyed mounting success in treating infectious diseases, spending $150 to $200 to cure TB patients in their homes compared with $15,000 to $20,000 in a U.S. hospital setting. In 1993, the MacArthur Foundation recognized his work with a $220,000 grant that he plowed into his burgeoning program.

Several people shared credit for PIH' s growing success, none more than co-founder Jim Yong Kim, who was born in South Korea and grew up in one of the only two Asian families in Muscatine, Iowa. Like his friend and fellow Harvard student, Kim was a physician and medical anthropologist with M.D. and Ph.D. degrees. Kim focused his energy on helping Farmer design better treatment protocols and badgering U.S. and foreign pharmaceutical companies to cut deals for cheaper and more-effective drugs.

In 1996, PIH faced an outbreak of patients with drug-resistant TB in a Lima, Peru, shantytown. Instead of trying the usual frontline antibiotics, which didn't work, PIH administered a carefully calibrated regimen of as many as seven other drugs to patients in their homes, along with needed social services. Cure rates exceeded a stunning 80 percent--better than in U.S. hospitals.

Now Farmer and Kim--who later received his own MacArthur genius award--had a larger goal: to wipe out TB throughout Peru and in other developing countries. And they saw no reason that their successful PIH treatment model couldn't be applied to other catastrophic infectious diseases like HIV/ AIDS and malaria. That required serious money. Kim had been building a relationship with the Bill and Melinda Gates Foundation, and in 2000, the foundation gave PIH $45 million.

That was enough to allow PIH not only to launch a nationwide TB offensive in Peru but to establish a pilot project in Russia as well. More funding soon followed. In 2002, PIH received a $13 million grant from the Global Fund for new facilities and equipment for improvements at the Cange medical complex. Last April, the William J. Clinton Presidential Foundation launched a $10 million HIV/AIDS initiative, and PIH is responsible for establishing the first phase in Rwanda. And in September, PIH was awarded the 2005 Conrad N. Hilton Humanitarian Prize of $1.5 million for significantly alleviating human suffering.