Clipping It's Wings; Scientists hope a new technique will help them develop a vaccine against the bird flu virus before it leaps to humans.(Cover Story)

Byline: Fred Guterl, With Michael Hastings, Jonathan Adams, Alexandra A. Seno, Scott Worden and Sarah Schafer

The life of a poultry farmer in the sleepy Cambodian village of Phuong Peay is not exactly eventful, but the job does have its worries. Like many of his fellow farmers, 50-year-old Chheng Kim Seang's biggest concern is usually the health of his birds. His livelihood depends on it. So when he walked into the ramshackle wooden shed that houses his chickens one morning late last December and found a few dead chicks, and when a week later perfectly healthy roosters and hens also starting dying, he assumed the worst: cholera. To cut his losses, he injected the live birds with medicine and sold them to a wholesaler. Shortly afterward, on Jan. 13, government officials showed up to carry out tests on the farm opposite Chheng's. Their conclusion, announced on Jan. 24, didn't confirm Chheng's worst fears, it surpassed them. His chickens were likely victims of H5N1--the bird-flu virus sweeping Asia. The virus has been known on occasion to kill people with deadly efficiency. Now Chheng fears for his life. "When I breathe at night," he says, "I wonder if I am sick."

Whether Chheng really is sick or just hypochondriacal, his fear is warranted. So far H5N1 has claimed mainly chickens--millions of them have died from the flu in recent weeks and 25 million more have been burned, or bagged and buried alive, in an effort (vain, so far) to keep the disease from spreading. The virus has infected only 11 people so far this year: most of them, like Chheng, had probably come into contact with the birds' feces or perhaps inhaled infected…