Good news is rare for sufferers of chronic fatigue syndrome, so when a team of researchers reported last fall that the mysterious condition was associated with a retrovirus, it made a splash.

The paper, published in the prestigious journal Science, suggested that the virus could somehow be helping to cause the disease. Drug companies expressed interest, and patients lit up the Internet with expressions of hope. One blogger posted photos of a party, complete with hats reading "I ♥ retrovirii" and a shrine to the paper's lead author, retroviral immunologist Judy Mikovits.

Nine months later, the joyous mood has soured. Five research teams trying to confirm the finding have reported in journals or at conferences that they could not find the retrovirus, known as XMRV, in patients diagnosed with chronic fatigue syndrome, casting grave doubts on the connection.

In response, Mikovits has accused other researchers of bias and amped up efforts to sound the alarm over what she views as an epic health crisis. Invoking the world's slow response to AIDS, she warned that XMRV infection "could be the worst epidemic in U.S. history." Though her published findings address only chronic fatigue syndrome, Mikovits also has publicly linked the retrovirus to autism, atypical multiple sclerosis and other disorders.

Meanwhile, some people with chronic fatigue syndrome already are getting tested for XMRV and taking toxic drugs intended to treat the retrovirus that causes AIDS — an idea Mikovits does not endorse but declines to oppose.

The story of XMRV and chronic fatigue syndrome is unfolding in a uniquely modern way, highlighting the clash between slow, methodical science and a plugged-in world ready to act on a single piece of information. It also puts the spotlight on a scientist whose unorthodox statements have raised eyebrows among colleagues while finding a receptive audience among patients desperate for answers.

"Right now it is chaotic," said John Coffin of Tufts University, a retrovirus expert who co-wrote a positive commentary accompanying the Science paper. "It is not impossible that there is something fundamentally wrong with the initial study. Everything is on the table."

Mikovits said in an interview and by e-mail that she feels her finding is being ignored by a dithering, even hostile scientific world. A retroviral scientist with decades of experience at the National Cancer Institute, she was hired in 2006 to head the research program at the Whittemore Peterson Institute for Neuro-Immune Disease in Reno, Nev.

In its Science paper, Mikovits' team, which included scientists from the Cleveland Clinic and the National Cancer Institute, reported finding evidence of XMRV infection in 67% of 101 chronic fatigue syndrome patients but in only a handful of people without the disorder.

"It was an incredibly proud day," Mikovits said of the paper's publication. "I got calls from around the world. Dubai, China, you name it."

For patients, such a report can seem like a long-awaited answer. But for scientists, a single paper raises questions. Are the findings correct? What do they mean? And, perhaps most important, can we confirm it?

'Extraordinary proof'

Even the best scientists can be wrong. Findings must be tested and confirmed by other researchers before they can be trusted. And that has yet to happen for XMRV and chronic fatigue syndrome.

"Extraordinary claims require extraordinary proof," said Dr. Pat Moore, director of the cancer virology program at the University of Pittsburgh Cancer Institute and the co-discoverer of two viruses that cause cancer. "It's important in cases that have a lot of clinical implications like this, where there are a lot of people desperate for an answer."

Other pathogens — Epstein-Barr virus, human herpesvirus-6, the retrovirus HTLV-II — have been fingered in the past as possible causes of chronic fatigue syndrome, but none has stuck. Proving that a retrovirus causes a specific disease is especially difficult, experts note. And contamination in the lab, which is always possible and challenging to detect, can wildly skew results.

"Once you start having contamination, then whatever disease you look at, you will find an association," said British retrovirologist Robin Weiss.

His lab published evidence of a new human retrovirus, but it turned out that his lab had been contaminated with a rabbit virus instead. "It took four years to work out," he said. "It was a bit embarrassing."

Mikovits called the contamination issue "a red herring."

"Contamination? Absolutely not," said Mike Hillerby, vice president of the Whittemore Peterson Institute. The goal of the institute — founded by Annette Whittemore, a wealthy Nevadan whose daughter has chronic fatigue syndrome — is to develop treatments as well as do basic science.