No physical explanation for delusional infestations

NEW YORK Mon May 16, 2011 4:23pm EDT

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NEW YORK (Reuters Health) - People complaining that they were infected with bugs, worms, eggs, fibers, and even triangles, generally had a clean report on medical exams a new study finds.

Although many of the patients diagnosed with "delusional infestation" did have dermatitis -- an itchy skin condition -- the researchers weren't sure if that was causing the symptoms, or if it was a result of excessive scratching or medications the patients had applied to "treat" their problem.

Whether delusional infestation -- also known as Morgellons Disease -- is a psychiatric condition, or whether people who complain of the mysterious skin symptoms might have an underlying physical disease continues to be debated and investigated. According to the Centers for Disease Control and Prevention, which is looking into the condition, sufferers have also reported fatigue, joint pain, and short term memory loss.

In cases of delusional infestation, "patients often complain that the physician isn't examining their skin closely enough to see the infesting organisms," Dr. Mark Davis of the Mayo Clinic in Rochester, Minnesota, told Reuters Health in an email.

"This study indicates that even when skin biopsies are obtained, and specimens of the organisms brought by the patients are carefully examined, there is no objective evidence of skin infestation," added Davis, who worked on the new study.

Davis and his colleagues reviewed the cases of 108 patients who were diagnosed with delusional infestation at the Mayo Clinic between 2001 and 2007.

All of those patients believed they were infested with bugs, worms, or inanimate objects, and complained of strange skin sensations, according to the report published in Archives of Dermatology.

Doctors did a biopsy on 80 of those patients to look more closely at the skin, and found no evidence of an infestation. Most patients also brought in skin flakes, scabs, or hairs for testing -- none of which had anything that would explain patients' symptoms.

More than half of the biopsies did show dermatitis, a skin condition marked by inflammation and red and itchy skin. But the researchers said they weren't sure if that could be leading to patients' symptoms and beliefs that they were infested -- or if their skin was inflamed because of scratching and various attempts at treating the perceived infestation.

In at least one case, a patient's symptoms were partially explained by an underlying medical condition. The patient initially had rectal itching and tingling that turned into a crawling sensation, the authors report -- which led her to believe that she was infested with eggs and non-living things. In the end, she was diagnosed with the virus that causes herpes.

Davis said reports show that some patients with a delusional infestation may also have other medical or psychiatric conditions -- but that some researchers believe it's a type of hypochondria that is generally seen alone, without other conditions.

While there are no published estimates of how common delusional infestation is, the CDC has been researching that question, as well as what type of people tend to report symptoms. Researchers there prefer the term "unexplained dermopathy."

"It is an unexplained and debilitating illness of unknown cause," a CDC spokesperson told Reuters Health. "We recognize that...healthcare providers are perplexed and frustrated" and patients and their families are suffering, the spokesperson added.

Davis said that it's still important for doctors to take a patient's history and do a physical exam if they suspect delusional infestation but aren't positive. "If there is any possibility that the patient's complaints/concerns could be explained by anything other than delusional infestation, then all relevant tests should be done," he concluded.

SOURCE: bit.ly/aAdwaR Archives of Dermatology, online May 16, 2011.

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