ATLANTA — Imagine having the feeling that tiny bugs are crawling on your body, that you have oozing sores and mysterious fibers sprouting from your skin. Sound like a horror movie? Well, at one point several years ago, government doctors were getting up to 20 calls a day from people saying they had such symptoms.

Many of these people were in California and one of that state's U.S. senators, Dianne Feinstein, asked for a scientific study. In 2008, federal health officials began to study people saying they were affected by this freakish condition called Morgellons.

The study cost nearly $600,000. Its long-awaited results, released Wednesday, conclude that Morgellons exists only in the patients' minds.

"We found no infectious cause," said Mark Eberhard, a Centers for Disease Control and Prevention (CDC) official who was part of the 15-member study team.

The study appears in PLoS One, one of the Public Library of Science journals.

Sufferers of Morgellons (mor-GELL-uns) describe a variety of symptoms, including fatigue, erupting sores, crawling sensations on their skin and mysterious red, blue or black fibers that sprout from their skin. Some say they've suffered for decades, but the syndrome wasn't named until 2002, when "Morgellons" was chosen from a 1674 medical paper describing similar symptoms.

Afflicted patients have documented their suffering on websites, and many have vainly searched for a doctor who believed them. Some doctors believe the condition is a form of delusional parasitosis, a psychosis in which people believe they are infected with parasites.

The CDC study focused on more than 3 million people who lived in 13 counties in Northern California, a location chosen in part because all had health insurance through Kaiser Permanente of Northern California, which had a research arm that could assist in the project. Also, many of the anecdotal reports of Morgellons came from the area.

Blood and urine tests and skin biopsies checked for dozens of infectious diseases, including fungus and bacteria that could cause some of the symptoms. The researchers found none that would explain the cases.

Experts warn of nanomaterials

Tiny substances called nanomaterials, engineered on the scale of a billionth of a meter, perhaps one ten-thousandth the width of a human hair, or less, have moved into the marketplace over the past decade, in products as varied as cosmetics, clothing and paint. But an expert panel of the National Academy of Sciences said Wednesday not enough is known about their potential health and environmental risks. Nanoscale forms of substances like silver, carbon, zinc and aluminum have many useful properties. Nano zinc oxide sunscreen goes on smoothly, for example, and nano carbon is lighter and stronger than its everyday form. But researchers say these products and others can also be ingested, inhaled or possibly absorbed through the skin.

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