Four years ago, after being bitten by a deer tick, Michelle Backes got treated immediately for Lyme disease. She thought she was safe until three months later, when her body started going numb. Then the onetime teacher from Lindstrom, Minn., turned to a highly controversial therapy: more than a year's worth of antibiotics.

It is, say medical experts, a reckless, unproven and potentially dangerous approach.

But today, Backes, 39, is fit enough to run marathons and is helping lead a grass-roots effort to change the way doctors treat patients like her. "We have to be little renegades," she said in an interview.

Lyme disease activists -- who call themselves "Lymies" -- are speaking out in courtrooms, state legislatures and even a new documentary, "Under Our Skin," to argue that the experts are wrong. They may have a growing audience: Some 1,000 Lyme disease cases were reported in Minnesota in 2008, a fourfold increase since 1998.

Last month, they scored a victory in Minnesota. With the help of some sympathetic legislators, activists from the Minnesota Lyme Action Support Group pressured the state Board of Medicine to forgo, for now, the ability to discipline doctors for using the unproven treatment.

It was extraordinary, in part because the board has never disciplined -- or even received a complaint about -- a doctor for using such treatments, said Rob Leach, the board's executive director. Yet the board agreed to adopt a five-year moratorium to prevent legislation that might have tied its hands further. "It was the lesser of two evils, as far as we were concerned," said Leach. Advocates say that a few doctors have been disciplined in other states for using the unproven treatment, and that some physicians in Minnesota have said they won't offer it because they're afraid of facing the same fate.

Dr. Johan S. Bakken, an infectious-disease expert at St. Luke's Hospital in Duluth, calls it "a sad statement when politicians begin to practice medicine without a license."

The problem, he and others say, is that many patients blame a wide constellation of painful and disabling symptoms -- from panic attacks to impotence to memory loss -- on what they call "chronic Lyme disease," without any evidence they were ever infected.

There's also concern that overuse of antibiotics can weaken their effectiveness and backfire on patients.

"We understand that people are suffering and we don't deny that, but you need to apply the right remedy for the right condition," said Bakken. "Now this has all been carried into the political arena. The basic message becomes, 'Don't confuse us with the facts.'"

A tell-tale rash

Michelle Backes has no doubt she was exposed to Lyme disease. She found the tick on her left thigh a day after a run in a state park near Marine on St. Croix in May 2006 and noticed the tell-tale circular red rash on her skin.

Her doctor put her on standard treatment -- 10 days of antibiotics -- and sent her home.

Untreated, Lyme disease can cause arthritis, heart damage and other complications. But Backes didn't experience any of them. "I was fine," she said. "I'd thought I was done with Lyme."

Three months later, when she was competing in a triathlon, she noticed that her lip was numb. By the end of the race, after swimming, biking and running, "my whole right leg was numb," she said.

A specialist said she might have multiple sclerosis, especially after a brain scan found the distinctive MS "lesions." But when an acquaintance suggested it might be lingering effects of Lyme, it made "a lot of sense," she said.

Backes said she couldn't find anyone in Minnesota willing to give the treatment she'd heard about: long-term antibiotics. So she went to Missouri, where a doctor told her she had a "99 percent chance" of recovery. She took antibiotics daily for the next 14 months. Her "crushing fatigue," dizziness and other symptoms slowly got better until "I was symptom-free."

'A very nasty process'

To Bakken, the infectious disease expert from Duluth, that treatment makes no sense. But four years ago, he discovered how explosive the debate could be when he helped write the 2006 national guidelines on Lyme disease for the Infectious Diseases Society of America.

The guidelines said antibiotics should be given for 10 to 28 days, and that the claims of any benefit from longer-term treatment are unproven.

That fall, Connecticut's attorney general, Richard Blumenthal, launched an antitrust investigation of the group, saying the guidelines were flawed and being used by insurers to deny patients care. He later accused members of "undisclosed" conflicts of interest in drafting the guidelines.

"Unprecedented," Bakken said of the investigation, "a very nasty process."

The infectious disease group denied the allegations, but as part of a 2008 settlement agreed to sponsor an independent review of the guidelines, expected later this month.

But Dr. Elizabeth Maloney, a onetime family physician in Wyoming, Minn., says the evidence isn't cut and dried.

"The question becomes, what do we do for the people in whom standard therapy did not work?" said Maloney, medical adviser to the Minnesota Lyme Action Support Group.

While no studies prove long-term antibiotics work, she believes it's still an open question scientifically, especially as researchers learn more about the disease. "The science isn't here yet to have restrictive guidelines in place."

The fact is that some patients improve after months or years of suffering, she said, and "to do nothing is to potentially condemn a patient to ill health and possibly death from Lyme disease."

But Dr. Gary Kravitz, an infectious-disease specialist in St. Paul, says the advocates are "misguided." He says many of these patients probably don't have Lyme disease at all; it's become a catchall for a "laundry list of symptoms," much like chronic fatigue syndrome a few years ago.

Kravitz cited the case of a Minnesota woman who had lupus, but quit her medication when she became convinced she had chronic Lyme disease, and died. "It makes me really angry as a physician," he said. "[They] start treating these people with antibiotics under some blind faith that this causes [their] symptoms."

Maloney agrees that could be a danger. "I really do caution people to not see Lyme everywhere, because that's not helpful."

Backes, though, says she doesn't need any more evidence. "It made the difference for me," she said of her treatment.

But to Bakken, the fact that some people feel better on antibiotics doesn't mean that's the right treatment. "There's a very strong placebo effect," he said. "Beliefs can move mountains."

Maura Lerner • 612-673-7384