AIDS was the last thing Gui Xien expected to find in the remote peasant villages of China’s Henan province. But when he visited there in 1999, as a favor to a fellow doctor whose patients were dying from a mysterious disease, it didn’t take Gui long to make a diagnosis. The stories were all the same: first the husband would fall ill, then his wife, and after a few months, both would be dead, covered in sores and dark, wine-colored blotches. Gui had stumbled on a full-fledged AIDS epidemic, something he had only read about in medical journals. While in school, he says quietly, “I had no interest to study AIDS because I thought AIDS cannot become a serious medical problem in China. I was wrong.” Gui, 68, an infectious-disease specialist at Wuhan University, immediately informed provincial health authorities that AIDS had somehow broken out of the usual high-risk groups–homosexual men, intravenous-drug users and commercial-sex workers–and infiltrated the general population. But the mystery remained: How had this “foreigner’s disease” come to infect poor rice farmers who scrape by on 2,000 yuan a year and rarely leave their village? The answer, when Gui hit on it, turned out to be a political hot potato. In the 1980s, the Chinese government launched a drive to replenish dwindling blood-bank supplies and paid donors for their plasma. For the impoverished farmers, it was an easy way to supplement their income. “When I asked if they donated blood, many said yes, many, many times–30, 40, sometimes 100 to 200 times,” Gui recalls. Tragically, the needles used–some in the hands of entrepreneurial middlemen known locally as “blood heads”–were not always sterile. All it would need for the virus to take hold was one HIV-positive donor. Gui took 11 samples from the villagers, but could afford to test only six of them, with 1,600 yuan out of his own pocket. All were positive for HIV. But Henan health officials, reluctant to expose an outbreak that originated in a government-sponsored program, were slow to respond and refused to allow Gui to return to the villages. So he and three students sneaked back in during a long weekend holiday when he knew the gatekeepers might be off duty. For three days he went house to house, collecting samples, counseling patients and explaining how the virus is spread. This time Gui sent his report directly to Beijing, where it was treated with the seriousness it deserved. Henan officials were finally pressured into action, but this only made Gui more unpopular in the province, and he became the target of smear campaigns and physical threats. With the central government now involved, local authorities could no longer hide what the world has come to know as China’s AIDS villages. Today a health clinic in the first village Gui visited provides free HIV testing and antiretroviral treatments, and a charity home shelters orphans and the elderly whose caretakers have died of AIDS. For Gui, this is only the beginning. “They are my friends,” he says of the people he continues to look after. A modest man, he is far more comfortable talking about the villagers than discussing his role in revealing the epidemic. His most treasured possession is a metal plaque from the farmers that reads, TO GUI: A ROLE MODEL FOR HELPING PEOPLE.