The way it looked to Marshall, people infected by the bug first developed stomach inflammation, and then some fraction of those went on to develop chronic indigestion or peptic ulcer. (Later, he even began to think that the bug might cause cancer.) And as far as he could tell, the bug itself wasn't some new pathogen that had sprung out of the rain forest and into the belly of humanity; he thought that his older patients had probably been infected for decades. When Marshall finished speaking, an audience member stood up and gently inquired, “Dr. Marshall what causes peptic ulcers in people who don't have the bacteria?” “If you don't have the bacteria, you don't have a peptic ulcer” Marshall said. He might as well have said he knew the secret of cold fusion. The scientists chuckled and murmured and shook their heads a little embarrassed for a junior colleague whose debut was such a disaster. Dr. Martin Blaser, the director of the Division of Infection Diseases at the Vanderbilt University School of Medicine, was in the audience. Marshall's talk struck him then as “the most preposterous thing I ever heard” he says. “I thought, this guy is a madman.” But far from simply dismissing Marshall's ideas, dozens of scientists more or less independently paid him the highest tribute their profession could bestow; they set out to prove him wrong. Dr. David T. Graham, a distinguished gastroenterology researcher at the Veterans Affairs Medical Center in Houston, recalls his first impression of Marshall's work.