They complain of mysterious, creepy symptoms: bugs — or some form of infestation — crawling beneath their skin, sometimes burrowing to the surface, leaving odd specks and colored filaments in their wake.
They have flocked to websites to share details of their malady, which they call Morgellons disease; they have charged the medical community with ignoring their plight and have strong-armed the government into studying it.
They go from doctor to doctor, carrying specimens in Ziploc bags and on glass slides, desperate to find a physical cause.
Although one patient who consulted dermatologists for Morgellons was found to have pubic lice, microscopic examination showed that none of the remaining 107 patients — who were seen over a seven-year period ending in 2007 — had any evidence of infestation by bugs or parasites, despite their firm conviction that they did.
Instead, the authors concluded, the rashes, eruptions and skin ulcerations patients suffered were either mundane skin conditions that gave rise to delusions of infestation, or the result of sufferers scratching or picking at their skin to make it go away.
And the fibers and filaments so often described and offered as evidence of infestation were, upon microscopic examination, skin flakes, scabs, hair, lint, textile fiber and everyday debris.
Two fruit flies, which do not colonize the human body, were found, as well as one mite and one tick.
The review of patients' records from the Mayo Clinic is the first major study to conclude that a seeming outbreak of subcutaneous creepy-crawlies is not evidence of a new pathogen abroad in the land: rather, patients suffering such symptoms more likely have a psychological disorder long described in dermatological literature as "delusional parasitosis."
"This study is important for patients," the authors wrote. "Patients frequently believe that physicians are dismissive of their concerns and are not examining their skin closely enough, and therefore patients request that more testing be performed. This showed that biopsy results do not change a physician's clinical diagnosis of delusional infestation."
Results of another, three-year study, undertaken by the Centers for Disease Control and Prevention and Kaiser Permanente of Northern California, are slated for release in the next few months. That study was launched in January 2008 after patients and a small group of medical professionals led by an organization called the Morgellons Research Foundation advocated for a full-scale government investigation of their symptoms.
The CDC and Kaiser scientists conducted skin biopsies, physical and psychiatric evaluations of sufferers and microscopic analysis of samples. The findings are now under review by independent experts.
"We recognize it has taken time, and people and their families are suffering, but at same time, it's important to release these findings appropriately and to ensure their scientific integrity," said CDC spokeswoman Lola Russell.
The Mayo Clinic findings are certain to be bitter medicine for patients who identify themselves as sufferers of Morgellons disease. The Internet is home to a growing community of patients certain that their symptoms are evidence of a new and very real disorder. Study lead author Dr. Mark D.P. Davis, a Mayo Clinic dermatologist, said he doubted the study would convince such patients that their disease originates in their brains and not under their skin.
"They feel you're still missing something even if you've gone the extra mile," Davis said.
Several board members and a spokesperson for the Morgellons Research Foundation could not be reached for comment.
Dr. Noah Craft, a dermatologist at Harbor-UCLA Medical Center, praised the Mayo work as "the best study done to date" on the bizarre constellation of symptoms called Morgellons. He commended the Mayo researchers "for putting in the effort to understand a disease that's becoming more and more important in our culture today."
At the same time, Craft cautioned that dermatologists and primary-care physicians who see patients with similar complaints should not automatically conclude, based on the study, that they are all delusional.
"Infrequently, we do find real bugs. So everybody gets their due diligence," he said. And, he added, taking a patient's complaints seriously will often help him or her take the next step in cases where a physical cause of their agony cannot be found.
"I have a growing numbers of patients who respond really well to medicines that treat the brain," he said. "I know it's frustrating, but I often encourage them to try it if we can't get to a diagnosis."