Delusions of Parasitosis 

  • Author: Noah S Scheinfeld, MD, JD, FAAD; Chief Editor: Dirk M Elston, MD   more...
 
Updated: Jul 18, 2011
 

Background

Delusions of parasitosis manifest in the patient's firm belief that he or she has pruritus due to an infestation with insects. Patients may present with clothing lint, pieces of skin, or other debris contained in plastic wrap, on adhesive tape, or in matchboxes. They typically state that these contain the parasites; however, these collections have no insects or parasites. This presentation is called the matchbox sign, or what the authors term the "Saran-wrap sign."

The patients have no obvious cognitive impairment, and abnormal organic factors are absent. True infestations and primary systemic diseases that cause pruritus are not involved. Primary skin lesions are not present. Physical examination may reveal no lesions, but only linear erosions with crusts, prurigo nodularis, and/or ulcers.

The classification of delusions of parasitosis is complicated. It is considered primarily a monosymptomatic hypochondriacal psychosis and has been associated with schizophrenia, obsessional states, bipolar disorder, depression, and anxiety disorders. Delusions of parasitosis occur primarily in white middle-aged or older women, although the condition has been reported in all age groups and in men.

Savely et al[1] introduced the term Morgellon disease to describe a condition characterized by fibers attached to the skin. The entity appears to be little more than a new designation for delusions of parasitosis. Koblenzer[2] and Waddell and Burke[3] have discussed the utility of the term, with Murase et al[4] finding the term useful for building a therapeutic alliance with patients with delusions of parasitosis. The Centers for Disease Control and Prevention is currently investigating Morgellon disease.[5]

William Harvey[6] of the Morgellons Research Foundation Medical Advisory Board states the following:

"All patients with Morgellons carry elevated laboratory proinflammatory markers, elevated insulin levels, and verifiable serologic evidence of 3 bacterial pathogens. They also show easily found physical markers such as peripheral neuropathy, delayed capillary refill, abnormal Romberg’s sign, decreased body temperature, and tachycardia. Most importantly they will improve, and most recover on antibiotics directed at the above pathogens."

The author of this article has not found reliable data to back up William Harvey's claims, but they are included here to comprehensively address this issue.

Walling and Swick[7] suggest abandoning 3 the diagnostic terms trichotillomania, delusions of parasitosis, and neurotic excoriation, which they believe have become barriers to treatment. Instead, they suggest using the alternative patient-centered nomenclature of neuromechanical alopecia, pseudoparasitic dysesthesia, and (simply) excoriation.

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Pathophysiology

The cause of delusions of parasitosis is unknown. It appears related to neurochemical pathology. This concept is underlined by its induction by psychoactive agents (eg, amphetamines, cocaine, and methylphenidate) and its coincidence with depression, schizophrenia, social isolation, and sensory impairment.

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Epidemiology

Frequency

United States

The exact prevalence of delusions of parasitosis is unknown.

International

The exact prevalence of delusions of parasitosis is unknown.

Mortality/Morbidity

The literature includes one report of suicide in a 40-year-old man with delusions of parasitosis.[8]

Race

Delusions of parasitosis appear to be more common in whites than in people of other races.

Sex

Delusions of parasitosis occur primarily in white middle-aged or older women, although the condition has been reported in all age groups and in men. The female-to-male ratio is approximately 2:1. More specifically, this ratio is 1:1 in people younger than 50 years and 3:1 in those older than 50 years.

Age

Delusions of parasitosis are more common in middle-aged and elderly persons than in others. The female-to-male ratio is 1:1 in people younger than 50 years and 3:1 in those older than 50 years.[9, 10]

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Contributor Information and Disclosures
Author

Noah S Scheinfeld, MD, JD, FAAD  Assistant Clinical Professor, Department of Dermatology, Columbia University College of Physicians and Surgeons; Consulting Staff, Department of Dermatology, St Luke's Roosevelt Hospital Center, Beth Israel Medical Center, and New York Eye and Ear Infirmary; Private Practice

Noah S Scheinfeld, MD, JD, FAAD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Optigenex Consulting fee Independent contractor

Specialty Editor Board

Franklin Flowers, MD  Chief, Division of Dermatology, Professor, Department of Medicine and Otolaryngology, Affiliate Associate Professor of Pediatrics and Pathology, University of Florida College of Medicine

Franklin Flowers, MD, is a member of the following medical societies: American College of Mohs Micrographic Surgery and Cutaneous Oncology

Disclosure: Nothing to disclose.

David F Butler, MD  Professor of Dermatology, Texas A&M University College of Medicine; Chair, Department of Dermatology, Director, Dermatology Residency Training Program, Scott and White Clinic, Northside Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, American Society for Dermatologic Surgery, American Society for MOHS Surgery, Association of Military Dermatologists, and Phi Beta Kappa

Disclosure: Nothing to disclose.

Jeffrey Meffert, MD  Assistant Clinical Professor of Dermatology, University of Texas School of Medicine at San Antonio

Jeffrey Meffert, MD is a member of the following medical societies: American Academy of Dermatology, American Medical Association, Association of Military Dermatologists, and Texas Dermatological Society

Disclosure: Nothing to disclose.

Catherine M Quirk, MD  Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania

Catherine M Quirk, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Dermatology

Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD  Director, Ackerman Academy of Dermatopathology, New York

Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

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