The first lesson a doctor needs to learn, says Andrew Wakefield, is to listen to his patients. And so when Rosemary Kessick brought in her son William in 1996, Wakefield listened carefully.

She described how William had deteriorated at age 15 months from a healthy developing toddler into a withdrawn, incommunicative child who screamed throughout the night, and how his bowels seemed on fire with constant diarrhea and pain. All of this had started, she said, within days after William received the MMR -- an injection known here as the "triple jab," designed to vaccinate youngsters against measles, mumps and rubella.

In the end Wakefield, a specialist in intestinal disease, did more than just listen. Working with colleagues, he came up with the hypothesis that William and other victims were suffering from a unique form of intestinal disorder related to their autism that might have been triggered by the MMR. He also claimed that the vaccine might be one reason for the soaring rates of autism in the developed world over the past two decades.

Public health officials insist he is wrong. While Wakefield continues publishing reports supporting his theory, study after study has failed to find a link between autism and MMR, and large numbers of doctors question his work.

But many parents have rallied to his side; vaccination rates in Britain have fallen steeply, and measles rates have begun to climb. Feeling hounded from his job in Britain, Wakefield is finding a new and receptive audience in the United States, where for now, at least, MMR vaccination rates remain stable. For parents and for much of the media, he has become a familiar archetype: the courageous lone crusader for truth and justice up against an uncaring, faceless medical establishment and a greedy pharmaceutical industry.

Now his credibility has taken another blow, from a Sunday Times newspaper report that Wakefield failed to disclose that his work had been supported by funds from a group of parents filing a lawsuit against the vaccine companies. Wakefield has vehemently denied any conflict of interest, but the editor of the Lancet, a distinguished medical journal, now says he would not have published Wakefield's groundbreaking 1998 report had he known about the funding.

Ten of the 13 physicians involved in the original report have withdrawn their support, and the cabinet secretary in charge of Britain's national health service has called for an investigation.

The Wakefield story is about public health and risk and the abiding mistrust that many people hold toward government officials, especially when it comes to issues of health and safety. It is also about how the media can transform complex matters of public policy into simple narratives with heroes and villains. And it is about one charismatic doctor who contends he holds the key to unlocking a medical mystery and that many of his colleagues are either too craven or too frightened to seek the truth.

A Study Is Launched

Tall, square-jawed and soft-spoken, Wakefield, now 47, was once a golden boy in the medical world. He trained at St. Mary's Hospital in London as a gastrointestinal surgeon, then spent several years doing research in Toronto, where he helped develop a novel theory on the causes of intestinal disease. By the early 1990s he was back in London, directing the inflammatory bowel disease study group at the Royal Free Hospital, one of Britain's premier teaching and research facilities.

Richard Horton, a former colleague who now edits the Lancet, once described him as "committed, engaging and charismatic. He asks big questions about diseases, and his ambition often brings quick and impressive results."

By the time Kessick came to see Wakefield with her son William, he had already begun to theorize about a link between the rising numbers of children with Crohn's disease, an inflammatory intestinal disorder, and the introduction of the MMR vaccine a few years earlier. William's case, Wakefield says, helped convince him that there could be a connection between the vaccine and autism as well.

Frustrated to the point of rage by what she saw as a general lack of understanding in the medical profession, Kessick had schooled herself in the disorder. She discovered that autism comes in many shapes and sizes, but its most general characteristic is profound isolation -- an autism sufferer cannot communicate with or understand others. Some children seem to suffer from autism at birth, while in others it develops in the first few years of life.

Kessick also learned that autism rates were rapidly rising -- although there is no agreement on exactly how fast or why. Many experts argue that improved diagnosis and deeper awareness among professionals have led to more accurate and earlier identification of the problem. Others contend that the absolute number of cases is rising, not just medicine's ability to find them. In their view, something in the environment must be to blame.

Based upon William's nightmarish decline, Kessick was certain that the MMR vaccine was at least one of the environmental factors. Most of the doctors she saw dismissed her as an obsessed and guilt-stricken mother looking for an answer to an unsolvable mystery. "Most of them were like, 'Oh, don't worry your little head about the MMR,' " she recalled.

Wakefield ran a battery of tests on William and concluded that Kessick might well be right about the MMR. He persuaded his colleagues at the Royal Free to launch a study of William and 11 other autistic children with similar disorders.

They published their findings in the Lancet in February 1998. In the article, they noted that most of the parents claimed their children's development had regressed within days or weeks of receiving the triple jab. The study itself drew no conclusion except that further investigation was needed. Still, Horton, the editor, was sufficiently uncertain about the findings that he commissioned a critical commentary that ran in the same issue.

But at a press conference announcing the report, Wakefield went a major step beyond what the study said. Asked about the MMR, he told reporters there was "sufficient concern in my own mind" that he would recommend children only receive individual vaccine injections -- not triple jabs -- until the matter was resolved.

One of his colleagues on the paper, pediatric gastroenterologist Simon Murch, immediately jumped in to insist that Wakefield was mistaken. "If this precipitates a scare and immunization rates go down," Murch warned, "as sure as night follows day, measles will return and children will die."

Murch proved to be right. Wakefield's remarks were highlighted in front-page headlines here the next day. The British public, which has grown increasingly suspicious of the medical establishment and the government after outbreaks of mad cow and foot-and-mouth disease, took notice.

By 2003 the MMR vaccination rate had fallen to 79 percent -- well below the 95 percent level experts say is needed to eradicate measles in the general population. Last year, British health officials reported 442 cases of measles, more than three times the number in 1996.

Career Turning Point

Wakefield went on to publish a series of papers seeking to reinforce his thesis and saying that he and other researchers had discovered measles viruses in the bowels of autism victims. In 2001 he co-authored a paper called "Through a Glass Darkly" contending that the MMR vaccine had been introduced without thorough safety tests.

But other researchers were failing to reproduce his results and various epidemiological studies of large, controlled populations failed to uncover a link between MMR and autism. The Institute of Medicine in Washington, part of the National Academy of Sciences, has compiled 14 large-scale studies in the United States, Canada and Europe that all exonerate the vaccine. Wakefield suggests each study has been flawed either because of its methodology or because its authors massaged the findings to get the answers they sought.

David Salisbury, head of Britain's national immunization program, said he understands why Wakefield's views gained traction with the public. "Unfortunately we have a long tradition of vaccine scares in this country," he said in an interview, "and people no longer accept the rather patronizing 'Do as I say because I'm the doctor.'"

Still, says Salisbury, the MMR has passed every test. "It's now been looked at by studies from numerous industrialized countries conducted in many different ways and they all come to the same conclusion -- we can find no evidence of an MMR-autism link," he said.

Britain's health service has refused to provide the more expensive single jabs Wakefield had recommended, arguing there was no reason to believe single vaccines would be less likely to cause an adverse reaction than the triple jab, and that by dragging out vaccinations over two years, fewer children would get the full series and many would be left exposed for longer periods. Those who want single jabs must go to private doctors and pay up to $300 per shot, whereas the MMR is free.

Sometimes the authorities have been heavy-handed. Some children whose parents refused to have them vaccinated have been struck off patients' lists at local clinics. When one local general practitioner started offering patients single jabs, the authorities hauled him before the General Medical Council and threatened to take away his license. The council dismissed the case.

Last fall the quasi-official Legal Services Commission pulled the plug on funding the legal case of Kessick and nearly 1,000 other plaintiffs on grounds the case was likely to fail. After spending about $26 million on research and other preparation, the commission declared, "There remains no acceptance within the worldwide medical authorities that MMR causes the symptoms seen in the children involved in this action."

Wakefield said his funding and responsibilities were curtailed to the point that in 2001 he left the Royal Free. He now gets most of his funding from Visceral, a nonprofit research group he set up in 1994.

"This is where one's career starts to go downhill," he said in a recent interview. "It's one thing to describe a new disease. But this is a case where the medical profession was wrong and the parents were right. What was I supposed to say when the parents pointed to the MMR -- 'Look, I'm terribly sorry but that's inconvenient so please go find another doctor'? "

But while Wakefield's credibility with his medical colleagues plummeted, his popularity with parents and the media continued to rise. The medical writer for the Sunday Telegraph newspaper won a British Press Award in 2002 for her coverage of Wakefield's work. Each positive story about him was promptly posted on the growing network of web sites of autism support groups.

"The media kept presenting this as a 50-50 proposition, claiming that the medical community was split down the middle on the MMR, when in fact almost all the science was on one side," said Fiona Fox, director of the Science Media Centre, which works with journalists reporting on science-related stories. "I think the public were ill-served by the media in this debate."

The government's case was not helped when Prime Minister Tony Blair, citing privacy considerations, refused to reveal whether his own son Leo, born in 2000, had received the triple jab. Blair insisted that the vaccine was safe, but parents continued to shy away.

Last December Britain's Channel Five television aired "Hear the Silence," a 90-minute docudrama that depicted the harrowing experiences of Kessick and other parents of autistic children and celebrated Wakefield's campaign on their behalf. The network organized a discussion program afterward and invited representatives from both sides to appear. Public health officials pulled out at the last minute, arguing that a debate would only lend credibility to the anti-MMR side. "We felt we'd be giving respectability to a program that was not respectable," Salisbury said.

The pullout left a handful of non-experts to make the pro-MMR argument, led by Michael Fitzpatrick, a general practitioner whose son is autistic. He says he got involved in the controversy after the mother of an autistic child told him she blamed herself for allowing her child to receive the triple jab. "What really annoyed me was Andy Wakefield setting himself up as spokesman for the parents when in fact what he was doing was visiting guilt upon many parents," said Fitzpatrick, who has just published a book, "MMR and Autism: What Parents Need to Know."

"People are anxious, they're frightened and so it's easy for many to adopt the default position and do nothing," Fitzpatrick said.

This is exactly how one mother reacted. Michelle Ellis, who was invited to listen to the arguments at the discussion program, said afterward she respected the case of the pro-MMR team but was still not willing to vaccinate her two young sons. "Statistics don't work for me here," she said.

The broadcast in many ways marked the apex of Wakefield's popularity. But while one part of the media was building him up, another was preparing to pull him down.

Last November a Sunday Times journalist who identified himself as Brian Lawrence paid a visit to Kessick's home north of London. He spent nearly six hours questioning her about William's autism, Wakefield and the entire MMR controversy. Afterward, she said, she felt like she had been grilled like a witness under cross-examination. She said that Lawrence didn't seem to believe anything she told him.

Her suspicion was not far off. "Brian Lawrence" was actually Brian Deer, a prize-winning investigative journalist with a reputation for breaking stories about the pharmaceutical industry. Deer said he used a false name -- Lawrence is actually his middle name -- because he didn't want Kessick to check his web site and find out that one of his specialties was tracking down false claims of damage from vaccines.

Parents' Court Case Suspended

Deer said he had planned to attend the trial of a major MMR lawsuit due to begin in April. When it was suspended indefinitely, he decided to launch his own probe. He found Kessick, like many of the plaintiffs, to be sympathetic people but less than reliable witnesses. He concluded that they wanted to believe MMR had caused their children's autism and that they may have bent the truth to prove it.

"I took her through her evidence as she would be asked in court," he recalls. After about several hours, he says, he told her she and the other plaintiffs could never win their case.

Wading into the huge volume of records in the case, Deer discovered something Wakefield had neglected to tell the Lancet: that the Royal Free Hospital had received some $90,000 in funding from the plaintiffs for Wakefield's help in doing a study of 10 of the victims. Four of the plaintiffs, including William Kessick, were among the dozen patients included in the Lancet article.

Rather than showing up at the Royal Free as consecutive referrals from disinterested general practitioners, Deer alleged, the Lancet 12 had been carefully chosen to prove Wakefield's theory and help lend credence to the lawsuit.

Wakefield insisted he had done nothing wrong -- that the Lancet study and the legal case had been kept entirely separate. But Lancet editor Horton said his former colleague should have disclosed the potential conflict before the original study was published. "If we had known the conflict of interest Dr. Wakefield had in this work, in my judgment it would have been rejected," Horton told the BBC.

A few weeks later, 10 of the 13 doctors on the original study issued a "Retraction of an interpretation" in which they declared that "no causal link was established between MMR vaccine and autism." Wakefield refused to sign.

The retraction was "absolute nonsense, just spin," he says. "There's absolutely no doubt they've been under huge pressure and it's very sad. We did discuss this in detail and I said, 'Guys, I can't sign up to this'."

Wakefield lost other allies as well. John O'Leary, an Irish microbiologist who has been one of his key collaborators, pronounced himself "shocked and disappointed" that Wakefield had not declared the potential conflict.

But Wakefield's core supporters, such as Rosemary Kessick, continue to believe in him. Robert Sawyer, chief executive of Visceral, Wakefield's research group, says donations are still coming in. But he expects to move Wakefield's research unit to Texas over the next few years. The United States, with its privatized health care system and entrepreneurial spirit is much more fertile ground than Britain for a medical pioneer like Wakefield, Sawyer said.

Andrew Wakefield, a British doctor, has alarmed parents, resulting in a drop in vaccination rates.Andrew Wakefield, at his home in London, discounts the methodologies used in MMR vaccine studies that dispute his theory.