Sections

Overview

Background

Delusions of parasitosis (DoP) 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.

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. Some reports have linked delusions of parasitosis to hyperthyroidism, which was deemed a secondary type of delusions of parasitosis, because it resolved with pimozide therapy and thyroid medications.

Next: Pathophysiology

Epidemiology

Frequency

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.^[16]

Race-, sex-, and age-related demographics

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

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.^{[17, 18]}

Next: Pathophysiology

Prognosis

Many patients with delusions of parasitosis refuse treatment and are lost to follow-up. For those patients who can be convinced to undertake treatment, the prognosis for a remission of the delusions is good.

Next: Pathophysiology

Patient Education

Patients must be reassured that they are not alone and that the physician will listen to them and sincerely desires to help them to get better. While one should not say anything to confirm the delusion, it is usually not helpful to forcefully confront patients with delusions of parasitosis.

Statements such as the following might be helpful: "I know you feel strongly that there are parasites here, and I'm sure that you itch severely, but I cannot prove that parasites are or have been the cause of your problem."^[19]

Clinical Presentation

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Murase JE, Wu JJ, Koo J. Morgellons disease: a rapport-enhancing term for delusions of parasitosis. J Am Acad Dermatol. 2006 Nov. 55(5):913-4. [QxMD MEDLINE Link].
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Reichenberg JS, Magid M, Jesser CA, Hall CS. Patients labeled with delusions of parasitosis compose a heterogenous group: a retrospective study from a referral center. J Am Acad Dermatol. 2013 Jan. 68(1):41-6, 46.e1-2. [QxMD MEDLINE Link].
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Bury JE, Bostwick JM. Iatrogenic delusional parasitosis: a case of physician-patient folie a deux. Gen Hosp Psychiatry. 2010 Mar-Apr. 32(2):210-2. [QxMD MEDLINE Link].
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Gassiep I, Griffin PM. Delusions of disseminated fungosis. Case Rep Infect Dis. 2014. 2014:458028. [QxMD MEDLINE Link].
Koo J, Lee CS. Delusions of parasitosis. A dermatologist's guide to diagnosis and treatment. Am J Clin Dermatol. 2001. 2(5):285-90. [QxMD MEDLINE Link].
Swick BL, Walling HW. Drug-induced delusions of parasitosis during treatment of Parkinson's disease. J Am Acad Dermatol. 2005 Dec. 53(6):1086-7. [QxMD MEDLINE Link].
Lopez PR, Rachael T, Leicht S, Smalligan RD. Gabapentin-induced delusions of parasitosis. South Med J. 2010. 103:711-2. [QxMD MEDLINE Link].
Steinert T, Studemund H. Acute delusional parasitosis under treatment with ciprofloxacin. Pharmacopsychiatry. 2006 Jul. 39(4):159-60. [QxMD MEDLINE Link].
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Krauseneck T, Soyka M. Delusional parasitosis associated with pemoline. Psychopathology. 2005 Mar-Apr. 38(2):103-4. [QxMD MEDLINE Link].
Guarneri F, Guarneri C, Mento G, Ioli A. Pseudo-delusory syndrome caused by Limothrips cerealium. Int J Dermatol. 2006 Mar. 45(3):197-9. [QxMD MEDLINE Link].
Ghaffari-Nejad A, Toofani K. Delusion of oral parasitosis in a patient with major depressive disorder. Arch Iran Med. 2006 Jan. 9(1):76-7. [QxMD MEDLINE Link].
Duggal H, Singh I. Delusional parasitosis as a presenting feature of dementia. J Neuropsychiatry Clin Neurosci. 2010 Winter. 22(1):123.E11-12. [QxMD MEDLINE Link].
Trager MJ, Hwang TN, McCulley TJ. Delusions of parasitosis of the eyelids. Ophthal Plast Reconstr Surg. 2008 Jul-Aug. 24(4):317-9. [QxMD MEDLINE Link].
Lim GC, Chen YF, Liu L, Huang SC, Lin KK, Hsiao CH. Camphor-related self-inflicted keratoconjunctivitis complicating delusions of parasitosis. Cornea. 2006 Dec. 25(10):1254-6. [QxMD MEDLINE Link].
Huber M, Karner M, Kirchler E, Lepping P, Freudenmann RW. Striatal lesions in delusional parasitosis revealed by magnetic resonance imaging. Prog Neuropsychopharmacol Biol Psychiatry. 2008 Dec 12. 32(8):1967-71. [QxMD MEDLINE Link].
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Author

Bettina E Bernstein, DO, DFAACAP, DFAPA Distinguished Fellow, American Academy of Child and Adolescent Psychiatry; Distinguished Fellow, American Psychiatric Association; Clinical Assistant Professor of Neurosciences and Psychiatry, Department of Psychiatry/Psychiatric Medicine, Philadelphia College of Osteopathic Medicine; Clinical Affiliate Medical Staff, Department of Child and Adolescent Psychiatry, Children's Hospital of Philadelphia; Consultant to Gemma Services, Private Practice; Consultant PMHCC/CBH at Family Court, Philadelphia

Bettina E Bernstein, DO, DFAACAP, DFAPA is a member of the following medical societies: American Academy of Child and Adolescent Psychiatry, American Psychiatric Association

Disclosure: Nothing to disclose.

Specialty Editor Board

David F Butler, MD Former Section Chief of Dermatology, Central Texas Veterans Healthcare System; Professor of Dermatology, Texas A&M University College of Medicine; Founding Chair, Department of Dermatology, Scott and White Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, Association of Military Dermatologists, Phi Beta Kappa, Texas Dermatological Society

Disclosure: Nothing to disclose.

Chief Editor

Glen L Xiong, MD Associate Clinical Professor, Department of Psychiatry and Behavioral Sciences, Department of Internal Medicine, University of California, Davis, School of Medicine; Medical Director, Sacramento County Mental Health Treatment Center

Glen L Xiong, MD is a member of the following medical societies: AMDA - The Society for Post-Acute and Long-Term Care Medicine, American College of Physicians, American Psychiatric Association, Central California Psychiatric Society

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: SafelyYou, Blue Cross Blue Shield<br/>book co-editor for: Wolter Kluwer, American Psychiatric Publishing Inc.

Additional Contributors

Franklin Flowers, MD Professor Emeritus, Department of Dermatology, Affiliate Associate Professor of Pathology, University of Florida College of Medicine

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

Disclosure: Nothing to disclose.

Noah S Scheinfeld, JD, MD, FAAD † Assistant Clinical Professor, Department of Dermatology, Weil Cornell Medical College; Consulting Staff, Department of Dermatology, St Luke's Roosevelt Hospital Center, Beth Israel Medical Center, New York Eye and Ear Infirmary; Assistant Attending Dermatologist, New York Presbyterian Hospital; Assistant Attending Dermatologist, Lenox Hill Hospital, North Shore-LIJ Health System; Private Practice

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

Disclosure: Nothing to disclose.

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Delusions of Parasitosis

Background

Pathophysiology

Epidemiology

Frequency

Mortality/Morbidity

Race-, sex-, and age-related demographics

Prognosis

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