Delusional parasitosis

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Delusional parasitosis
Other namesDelusional infestation[1] or Ekbom's syndrome[2][3]
Risk factorsSchizophrenia

Delusional parasitosis, is a delusional disorder in which individuals incorrectly believe they are infested with parasites, insects, or bugs, whereas in reality no such infestation is present.[4] Individuals with delusional parasitosis usually report tactile hallucinations known as formication, a sensation resembling insects crawling on or under the skin.

Delusional parasitosis is a mental disorder characterized by a fixed, false belief that a skin infestation exists, which is in contrast to cases of actual parasitosis, such as scabies and infestation with Demodex, in which a skin infestation is present and identifiable by a physician through physical examination or laboratory tests.[5][6]

The alternative name, Ekbom's syndrome, refers to neurologist Karl-Axel Ekbom,[7] who published seminal accounts of the disease in 1937 and 1938. (He also gave his name to the unrelated Willis–Ekbom disease (WED), more commonly known as restless legs syndrome.) Morgellons is considered to be a self-diagnosed form of this condition, in which individuals have sores that they believe contain some kind of fibers.

Signs and symptoms[edit]

Details of delusional parasitosis vary among sufferers, though it typically manifests as a crawling and pin-pricking sensation that is most commonly described as involving perceived parasites crawling upon or burrowing into the skin, sometimes accompanied by an actual physical sensation (known as formication; often associated with menopause, or sometimes exposure to household cleaning products).[4][8] Sufferers may injure themselves in attempts to be rid of the "parasites". Some are able to induce the condition in others through suggestion, in which case the term folie à deux may be applicable.[3][9]

Nearly any marking upon the skin, or small object or particle found on the person or their clothing, can be interpreted as evidence for the parasitic infestation, and sufferers commonly compulsively gather such "evidence" and then present it to medical professionals when seeking help.[4] This presentation of "evidence" is known as "the matchbox sign" because the "evidence" is frequently presented in a small container, such as a matchbox.[3]

Archives of Dermatology on May 16, 2011 published a Mayo Clinic study of 108 patients. It failed to find evidence of skin infestation despite doing skin biopsies and examining patient-provided specimens. The study, conducted from 2001 to 2007, concluded that the feeling of skin infestation was delusional parasitosis.[10][11]

Delusional parasitosis is observed more commonly in women, and the frequency is much higher past the age of 40.[3][12]

Delusory cleptoparasitosis is a form of delusion of parasitosis where the person believes the infestation is in their dwelling, rather than on or in their body.[13]

Morgellons is a form of delusional parasitosis in which people have painful skin sensations that they believe contain fibers of various kinds.[14][15][16][17][18]


Delusional parasitosis is divided into primary, secondary functional, and secondary organic groups.[19]


In primary delusional parasitosis, the delusions make up the entire disease entity: no additional deterioration of basic mental functioning or idiosyncratic thought processes exist. The parasitic delusions consist of a single delusional belief regarding some aspect of health. Medical experts refer to this phenomenon as "monosymptomatic hypochondriacal psychosis",[20] and sometimes as "true" delusional parasitosis. In the DSM-IV, it corresponds with "delusional disorder, somatic type".

Secondary functional[edit]

Secondary functional delusional parasitosis occurs when the delusions are associated with a psychiatric condition such as schizophrenia, obsessive-compulsive disorder or clinical depression.

Secondary organic[edit]

Secondary organic delusional parasitosis occurs when a medical illness or substance (medical or recreational) use causes the patient's symptoms. In the DSM-IV this situation corresponds with "psychotic disorder due to general medical condition". Physical illnesses that can underlie secondary organic delusional parasitosis include: hypothyroidism, cancer, cerebrovascular disease, tuberculosis, neurological disorders, vitamin B12 deficiency, and diabetes mellitus. Any illness or medication for which formication is a symptom or side effect can become a trigger or underlying cause of delusional parasitosis.

Other physiological factors which can cause formication and thus can sometimes lead to this condition include: menopause (i.e. hormone withdrawal); allergies, and drug abuse, including but not limited to cocaine abuse[21] and methamphetamine (as in amphetamine psychosis).[12] It appears that many of these physiological factors, as well as environmental factors such as airborne irritants, are capable of inducing a "crawling" sensation in otherwise healthy individuals; however, some people become fixated on the sensation and its possible meaning, and this fixation may then develop into delusional parasitosis.[12]


Secondary forms of delusional parasitosis are addressed by treatment of the primary associated psychological or physical condition. The primary form is treated much as other delusional disorders and schizophrenia. In the past, pimozide was the drug of choice when selecting from the typical antipsychotics. Currently, atypical antipsychotics such as olanzapine or risperidone are used as first line treatment.

Notably, sufferers often will reject the professional medical diagnosis of delusional parasitosis, and few patients willingly undergo treatment, despite demonstrable efficacy.[4]

Society and culture[edit]


The founder of the Morgellons Research Foundation, Mary Leitao,[22] coined the name in 2002, reviving it from a letter written by a physician in the mid-1600s.[23] Leitao and others involved in her foundation (who self-identified as having Morgellons) successfully lobbied members of the U.S. Congress and the U.S. Centers for Disease Control and Prevention (CDC) to investigate the condition in 2006.[24][25] CDC researchers issued the results of their multi-year study in January 2012, indicating that no disease organisms were present in people with Morgellons; the fibers found were likely cotton, concluding that the condition was "similar to more commonly recognized conditions such as delusional infestation".[26][27]

See also[edit]


  1. ^ Freudenmann, R. W.; Lepping, P. (2009). "Delusional Infestation". Clinical Microbiology Reviews. 22 (4): 690–732. doi:10.1128/CMR.00018-09. PMC 2772366. PMID 19822895.
  2. ^ Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. ISBN 978-1-4160-2999-1.
  3. ^ a b c d Hinkle, N.C. (2011). "Ekbom Syndrome: a delusional condition of "bugs in the skin"". Curr Psychiatry Rep. 13 (3): 178–86. doi:10.1007/s11920-011-0188-0. PMID 21344286.
  4. ^ a b c d Webb, J.P., Jr. (1993). "Case histories of individuals with delusions of parasitosis in southern California and a proposed protocol for initiating effective medical assistance". Bulletin of the Society of Vector Ecologists. 18 (1): 16–24.CS1 maint: multiple names: authors list (link)
  5. ^ Kligman, Albert M (2011). "Demodex folliculorum: Requirements for Understanding Its Role in Human Skin Disease". Journal of Investigative Dermatology. 131 (1): 8–10. doi:10.1038/jid.2010.335. PMID 21157421.
  6. ^ Jing, X., Shuling, G. and Ying, L. (2005). "Environmental scanning electron microscopy observation of the ultrastructure of Demodex". Microsc. Res. Tech. 68 (5): 284–289. doi:10.1002/jemt.20253. PMID 16315233.CS1 maint: multiple names: authors list (link)
  7. ^ Ekbom's syndrome II at Who Named It?
  8. ^ Amin, Omar (February 15, 2015). "The delusion of "delusional parasitosis"" (PDF). Parasite Testing.
  9. ^ Koblenzer, C.S. (1993). "The clinical presentation, diagnosis and treatment of delusions of parasitosis—a dermatologic perspective". Bulletin of the Society of Vector Ecologists. 18 (1): 6–10.
  10. ^ Hylwa SA, Bury JE, Davis MD, Pittelkow M, Bostwick JM (2011). "Delusional infestation, including delusions of parasitosis: results of histologic examination of skin biopsy and patient-provided skin specimens". Arch Dermatol. 147 (9): 1041–5. doi:10.1001/archdermatol.2011.114. PMID 21576554.
  11. ^ Walsh, Nancy; Zalman S. Agus (May 16, 2011). "Bugs and Worms in Patients' Heads, Not the Skin". MedPage Today. Retrieved 16 May 2011.
  12. ^ a b c Hinkle, Nancy C (2000). "Delusory Parasitosis" (PDF). American Entomologist. 46 (1): 17–25. doi:10.1093/ae/46.1.17. Archived from the original (PDF) on 2012-10-21.
  13. ^ Grace, Kenneth J (1987). "Delusory Cleptoparasitosis: Delusions of Arthropod Infestation in the Home". Pan-Pacific Entomologist. 63 (1): 1–4.
  14. ^ Halvorson, CR (October 2012). "An approach to the evaluation of delusional infestation". Cutis. 90 (4): E1–4. PMID 24005827.
  15. ^ Shmidt, E; Levitt, J (February 2012). "Dermatologic infestations". International Journal of Dermatology. 51 (2): 131–41. doi:10.1111/j.1365-4632.2011.05191.x. PMID 22250620.
  16. ^ Harth, W; Hermes, B; Freudenmann, RW (April 2010). "Morgellons in dermatology". Journal der Deutschen Dermatologischen Gesellschaft. 8 (4): 234–42. doi:10.1111/j.1610-0387.2009.07219.x. PMID 19878403.
  17. ^ Freudenmann, RW; Lepping, P (October 2009). "Delusional infestation". Clinical Microbiology Reviews. 22 (4): 690–732. doi:10.1128/cmr.00018-09. PMC 2772366. PMID 19822895.
  18. ^ Simpson, L; Baier, M (August 2009). "Disorder or delusion? Living with Morgellons disease". Journal of Psychosocial Nursing and Mental Health Services. 47 (8): 36–41. doi:10.3928/02793695-20090706-03. PMID 19681520.
  19. ^ Freinhar, Jack P (1984). "Delusions of parasitosis". Psychosomatics. 25 (1): 47–53. doi:10.1016/S0033-3182(84)73096-9. PMID 6701279.
  20. ^ FreedBerg; et al. (2003). Fitzpatrick's Dermatology in General Medicine (6th ed.). McGraw-Hill. p. 389. ISBN 978-0-07-138076-8.
  21. ^ Brewer, JD; Meves, A; Bostwick, JM; Hamacher, KL; Pittelkow, MR (September 2008). "Cocaine abuse: dermatologic manifestations and therapeutic approaches". Journal of the American Academy of Dermatology. 59 (3): 483–7. doi:10.1016/j.jaad.2008.03.040. PMID 18467002.
  22. ^ Harlan, Chico (2006-07-23). "Mom fights for answers on what's wrong with her son". Pittsburgh Post-Gazette. Retrieved 2007-08-04.
  23. ^ Edwards, Stassa (April 15, 2015), "Real Delusions of an Unreal Disease: A History of Morgellons", Jezebel
  24. ^ Schulte, Brigid (January 20, 2008). "Figments of the Imagination?". Washington Post Magazine. p. W10. Retrieved 2008-06-09.
  25. ^ "Unexplained Dermopathy (aka "Morgellons"), CDC Investigation". Centers For Disease Control. November 1, 2007. Archived from the original on June 3, 2016. Retrieved 2011-05-09.
  26. ^ Pearson, Michele L.; Selby, Joseph V.; Katz, Kenneth A.; Cantrell, Virginia; Braden, Christopher R.; Parise, Monica E.; Paddock, Christopher D.; Lewin-Smith, Michael R.; Kalasinsky, Victor F.; Goldstein, Felicia C.; Hightower, Allen W.; Papier, Arthur; Lewis, Brian; Motipara, Sarita; Eberhard, Mark L.; Unexplained Dermopathy Study, Team (2012). "Clinical, Epidemiologic, Histopathologic and Molecular Features of an Unexplained Dermopathy". PLoS ONE. 7 (1): e29908. Bibcode:2012PLoSO...729908P. doi:10.1371/journal.pone.0029908. PMC 3266263. PMID 22295070.
  27. ^ Aleccia, JoNel. "Mystery skin disease Morgellons has no clear cause, CDC study says". NBC News. Retrieved 2 April 2015.

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