For this study, published online May 16 in the Archives of Dermatology, researchers tested skin samples from 108 people -- 75 percent women -- who visited the Mayo Clinic between 2001 and 2007 and complained of animate and inanimate invaders. Patients had suffered for an average of 2.3 years.
Seventy-nine percent of the patients complained of bug infestations. Others were sure they had worms, eggs, fibers or other intruders, such as "specks," rotting wood fungus, glass and car oil.
After taking skin biopsies and/or examining skin samples provided by the patients, the researchers found that the majority of the skin samples showed signs of dermatitis and other skin conditions, such as ulceration or inflammation. Only one skin sample revealed an insect with infestation potential -- a pubic louse.
This suggests that skin inflammation and the accompanying discomfort might be an underlying pathological condition triggering the delusional symptoms, the authors said.
For more on delusional parasitosis, visit the University of California at Davis.
SOURCES: Steven R. Feldman, M.D., Ph.D., professor, dermatology, Wake Forest University School of Medicine, Winston-Salem, N.C.; Mark D. Davis, M.D., professor, dermatology, Mayo Clinic, Rochester, Minn.; May 16, 2011, Archives of Dermatology, online
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