Delusional parasitosis

Medical condition

A person scratching their arm, a common response to sensations like itching or crawling, which are frequently experienced in delusional parasitosis.

Delusional parasitosis (DP), also called delusional infestation,[1] is a mental health condition where a person falsely believes that that their body is infested with living or nonliving agents. Common examples of such agents include parasites, insects, or bacteria. This is a delusion due to the belief persisting despite evidence that no infestation is present.[2][3] People with this condition may have skin symptoms such as the urge to pick at one's skin (excoriation) or a sensation resembling insects crawling on or under the skin (formication). In Morgellons disease, a type of delusional parasitosis, people falsely believe harmful fibers are coming out of their skin and causing wounds.[3][4]

Delusional parasitosis is classified as a delusional disorder in the fifth revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). The precise cause is unknown. Current research suggests it may be linked to problems with dopamine in the brain, similar to psychotic disorders.[1] Diagnosis requires the delusion to be the only sign of psychosis, not caused by another medical condition, and present for at least a month. A defining characteristic of delusions is that the false belief cannot be corrected.[5] As a result, most affected individuals believe their delusion is true and do not accept treatment.[1] Antipsychotic medications can help with symptom remission.[6] Cognitive behavioral therapy and antidepressants can also decrease symptoms.[3][7]

The condition is rare and affects women twice as much as men.[3] The average age of individuals affected by the disorder is 57.[8] An alternative name, Ekbom's syndrome, honors the neurologist Karl-Axel Ekbom, who published seminal accounts of the disease in 1937 and 1938.[3]

## Classification

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Delusional parasitosis is classified as a delusional disorder of the somatic subtype in the Diagnostic and Statistical Manual of Mental Disorders (DSM5).[3][5] Since 2015, the most common name for the disorder is delusional parasitosis. The condition has also been called delusional infestation, delusory parasitosis, delusional ectoparasitosis, psychogenic parasitosis, Ekbom syndrome, dermatophobia, parasitophobia, formication and "cocaine bugs".[5]

Delusional parasitosis can occur in two different forms.[5] The first, primary delusional infestation, is a psychiatric disorder.[1] The second, secondary delusional infestation, is linked to other medical or psychiatric conditions.[1]

Morgellons is a form of delusional parasitosis. People with this condition have painful skin sensations that they believe are caused by fibers. This condition is similar to other delusional infestations. However, those self-diagnosed with Morgellons believe strings or fibers are present in their skin lesions.[3][5] Importantly, Morgellons disease is not listed in the International Classification of Diseases (ICD-11).[4]

Delusory cleptoparasitosis is a type of delusion where the person believes the infestation is in their home, rather than on or in their body.[9]

## Signs and symptoms

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People with delusional parasitosis believe that "parasites, worms, mites, bacteria, fungus" or similar organisms have infected them. Reasoning or logic cannot change this fixed, false belief.[5] Symptoms can differ among those with the condition. It often involves a crawling or pin-pricking sensation. Many describe it as a sensation of parasites crawling upon or burrowing into the skin. Sometimes, this includes a physical sensation (known as formication).[3][5][8] People with this condition may injure themselves trying to remove the "parasites". This can lead to skin damage such as excoriation, bruises, and cuts. Moreover, using harsh chemicals or cleaning obsessive can cause further harm.[8]

People with this condition recall events like a bug bite, travel, sharing clothes, or contact with someone they think was infected.[3] These exposures may cause the individual to pay attention to bodily sensations they usually ignore. The individual may then believe these symptoms are due to an infestation.[3] Those affected may see any skin mark or small object on them or their clothing as proof of a parasitic infestation. Those with the condition often collect such "evidence" to present to medical professionals. Medical professionals call this the "matchbox sign", "Ziploc bag sign" or "specimen sign." The name stems from the fact that the evidence is typically stored in a small container, like a matchbox.[3][8] The matchbox sign is present in five to eight out of every ten people with DP.[3] Related is a "digital specimen sign", in which individuals bring collections of photographs to document their condition.[3]

Similar delusions may be present in close relatives—a shared condition known as a folie à deux—that occurs in 5–15% of cases and is considered a shared psychotic disorder.[8] Because the internet and the media contribute to furthering shared delusions, DP has also been called folie à Internet; when affected people are separated, their symptoms typically subside, but most still require treatment.[8]

Approximately eight out of ten individuals with DP have co-occurring conditions—mainly depression, followed by substance abuse and anxiety; their personal and professional lives are frequently disrupted as they are extremely distressed about their symptoms.[10]

A 2011 Mayo Clinic study of 108 patients failed to find evidence of skin infestation in skin biopsies and patient-provided specimens; the study concluded that the feeling of skin infestation was DP.[3][11]

## Cause

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The cause of delusional parasitosis is unknown. Primary delusional parasitosis may result from high dopamine in the brain's striatum. This happens from diminished dopamine transporter (DAT) function.[3][8] The dopamine transporter regulates dopamine reabsorption in the brain.[3][8] For example, substances that block dopamine reuptake, like cocaine and methylphenidate, can cause symptoms like formication. Additionally, several conditions linked to faulty dopamine transporters can also lead to secondary delusional parasitosis. Examples of such conditions include: "schizophrenia, depression, traumatic brain injury, alcoholism, Parkinson's and Huntington's diseases, human immunodeficiency virus infection, and iron deficiency".[8] Providing further support for the dopamine theory, antipsychotics improve DP symptoms. This may be because they affect dopamine transmission.[8][5]

Secondary delusional parasitosis is caused by another medical or psychiatric disorder. Medical conditions associated with secondary delusional parasitosis include: deficiencies in vitamins such as B12 or folate, thyroid dysfunction, diabetes, Parkinson's disease, dementia, encephalitis, meningitis, and multiple sclerosis.[8][5] Additionally, some infectious diseases such as HIV and syphilis have also been associated with delusional infestation.[5] Secondary delusional parasitosis is also associated with substance use disorders. The most commonly associated substances include chronic alcohol use, alcohol withdrawal, long-term cocaine use, long-term amphetamine use.[5] Finally, there also a number of prescription drugs that may cause DP as a side effect. These include "phenelzine, pargyline, ketoconazole, corticosteroids, amantadine, ciprofloxacin, pegylated interferon alpha, and topiramate."[5]

## Diagnosis

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Delusional parasitosis is diagnosed when the delusion is the only symptom of psychosis, the delusion has lasted a month or longer, behavior is otherwise not markedly odd or impaired, mood disorders—if present at any time—have been comparatively brief, and the delusion cannot be better explained by another medical condition, mental disorder, or the effects of a substance. For diagnosis, the individual must attribute abnormal skin sensations to the belief that they have an infestation, and be convinced that they have an infestation even when evidence shows they do not.[3]

The condition is recognized in two forms: primary and secondary. In primary delusional parasitosis, the delusions are the only manifestation of a psychiatric disorder. Secondary delusional parasitosis occurs when another psychiatric condition, medical illness or substance (medical or recreational) use causes the symptoms; in these cases, the delusion is a symptom of another condition rather than the disorder itself.[5] Secondary forms of DP can be functional (due to mainly psychiatric disorders) or organic (due to other medical illness or organic disease).[8] The secondary organic form may be related to vitamin B12 deficiency, hypothyroidism, anemia, hepatitis, diabetes, HIV/AIDS, syphilis, or use of stimulants like methamphetamine and cocaine.[8][12]

Examination to rule out other causes is key to diagnosis.[8] Parasitic infestations are ruled out via skin examination and laboratory analyses. Bacterial infections may be present as a result of the individual constantly manipulating their skin. Other conditions that can cause itching skin are also ruled out; this includes a review of medications that may lead to similar symptoms.[8] Testing to rule out other conditions helps build a trusting relationship with the physician; this can include laboratory analysis such as a complete blood count, comprehensive metabolic panel, erythrocyte sedimentation rate, C-reactive protein, urinalysis for toxicology and thyroid-stimulating hormone, in addition to skin biopsies and dermatological tests to detect or rule out parasitic infestations.[3][10] Depending on symptoms, tests may be done for "human immunodeficiency virus, syphilis, viral hepatitis, B12 or folate deficiency", and allergies.[3]

### Differential

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Delusional parasitosis must be distinguished from scabies, mites, and other psychiatric conditions that may occur along with the delusion; these include schizophrenia, dementia, anxiety disorders, obsessive–compulsive disorder, and affective or substance-induced psychoses or other conditions such as anemia that may cause psychosis.[10]

Pruritus and other skin conditions are most commonly caused by mites, but may also be caused by "grocer's itch" from agricultural products, pet-induced dermatitis, caterpillar/moth dermatitis, or exposure to fiberglass. Several drugs, legal or illegal, such as amphetamines, dopamine agonists, opioids, and cocaine may also cause the skin sensations reported. Diseases that must be ruled out in differential diagnosis include hypothyroidism, and kidney or liver disease.[10] 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; some people become fixated on the sensation and its possible meaning, and this fixation may then develop into DP.[13]

## Treatment

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As of 2019, there have not been any studies that compare available treatments to placebo.[14] The only treatment that provides a cure, and the most effective treatment, is low doses of antipsychotic medication. Cognitive behavioral therapy (CBT) can also be useful. Risperidone is the treatment of choice.[3] For many years, the treatment of choice was pimozide, but it has a higher side effect profile than the newer antipsychotics.[10] Aripiprazole and ziprasidone are effective but have not been well studied for delusional parasitosis. Olanzapine is also effective. All are used at the lowest possible dosage, and increased gradually until symptoms remit.[3]

People with the condition often reject the professional medical diagnosis of delusional parasitosis, and few willingly undergo treatment, despite demonstrable efficacy, making the condition difficult to manage.[3][5][15] Reassuring the individual with DP that there is no evidence of infestation is usually ineffective, as the patient may reject that.[10] Because individuals with DP typically see many physicians with different specialties, and feel a sense of isolation and depression, gaining the patient's trust, and collaborating with other physicians, are key parts of the treatment approach.[8] Dermatologists may have more success introducing the use of medication as a way to alleviate the distress of itching.[8] Directly confronting individuals about delusions is unhelpful because by definition, the delusions are not likely to change; confrontation of beliefs via CBT is accomplished in those who are open to psychotherapy.[10] A five-phase approach to treatment is outlined by Heller et al. (2013) that seeks to establish rapport and trust between physician and patient.[3][16]

## Prognosis

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The average duration of the condition is about three years.[3] The condition leads to social isolation and affects employment.[3] Cure may be achieved with antipsychotics or by treating underlying psychiatric conditions.[3]

## Epidemiology

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While a rare disorder, delusional parasitosis is the most common of the hypochondriacal psychoses, and more common than other types of delusions such as those associated with body odor or halitosis.[5] It may be undetected because those who have it do not see a psychiatrist because they don't recognize the condition as a delusion.[5] A population-based study in Olmsted County, Minnesota, found a prevalence of 27 per 100,000 person-years and an incidence of almost 2 cases per 100,000 person-years.[5] The majority of dermatologists will see at least one person with DP during their career.[8]

It is observed twice as often in women than men. The highest incidence occurs in people in their 60s, but there is also a higher occurrence in people in their 30s, associated with substance use.[3] It occurs most often in "socially isolated" women with an average age of 57.[8]

Since the early 2000s, a strong internet presence has led to increasing self-diagnosis of Morgellons.[3]

## History

[edit]

Karl-Axel Ekbom, a Swedish neurologist, first described delusional parasitosis as "pre-senile delusion of infestation" in 1937.[3] The common name has changed many times since then. Ekbom originally used the German word dermatozoenwahn, but other countries used the term Ekbom's syndrome. That term fell out of favor because it also referred to restless legs syndrome (more specifically termed Willis–Ekbom disease (WED) or Wittmaack-Ekbom syndrome).[17][18] Other names that referenced "phobia" were rejected because anxiety disorder was not typical of the symptoms.[18] The eponymous Ekbom's disease was changed to "delusions of parasitosis" in 1946 in the English literature, when researchers J Wilson and H Miller described a series of cases, and to "delusional infestation" in 2009.[3][19] The most common name since 2015 has been "delusional parasitosis".[5]

Ekbom's original was translated to English in 2003; the authors hypothesized that James Harrington (1611–1677) may have been the "first recorded person to suffer from such delusions when he 'began to imagine that his sweat turned to flies, and sometimes to bees and other insects'."[20]

### Morgellons

[edit]

Main article: Morgellons

Mary Leitao, the founder of the Morgellons Research Foundation,[21] coined the name Morgellons in 2002, reviving it from a letter written by a physician in the mid-1600s.[22][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] The CDC published the results of its multi-year study in January 2012. The study found no underlying infectious condition and few disease organisms were present in people with Morgellons; the fibers found were likely cotton, and the condition was "similar to more commonly recognized conditions such as delusional infestation".[26]

An active online community has supported the notion that Morgellons is an infectious disease, and propose an association with Lyme disease. Publications "largely from a single group of investigators" describe findings of spirochetes, keratin and collagen in skin samples of a small number of individuals; these findings are contradicted by the much larger studies conducted by the CDC.[5]

## Society and culture

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Jay Traver (1894–1974), a University of Massachusetts entomologist, has been characterized after her death as having made "one of the most remarkable mistakes ever published in a scientific entomological journal",[27] after publishing a 1951 account of what she called a mite infestation.[28] Her detailed description of her own experience with mites was later shown to be incorrect,[27] and has been described by others as a classic case of delusional parasitosis.[29][17][30][31] Matan Shelomi says the paper has done "permanent and lasting damage" to people with delusional parasitosis, "who widely circulate and cite articles such as Traver's and other pseudoscientific or false reports" via the internet, making treatment and cure more difficult.[30] He argues that the historical paper should be retracted because it has misled people about their delusion and that papers "written by or enabling deluded patients", along with internet-fed conspiracies and the related delusion of Morgellons, may increase.[30]

Shelomi published another study in 2013 of what he called scientific misconduct when a 2004 article in the Journal of the New York Entomological Society included what he says is photo manipulation of a matchbox specimen to support the claim that individuals with DP are infested with collembola.[32]

## See also

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* Stimulant psychosis
* Formication

## References

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1. ^ a b c d e Mendelsohn A, Sato T, Subedi A, Wurcel AG (July 2024). "State-of-the-Art Review: Evaluation and Management of Delusional Infestation". Clin Infect Dis. doi:10.1093/cid/ciae250. PMID 39039925.
2. ^ Waykar V, Wourms K, Tang M, Verghese J (22 October 2020). "Delusional infestation: an interface with psychiatry". BJPsych Advances. 27 (5): 343–348. doi:10.1192/bja.2020.69. ISSN 2056-4678.
3. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad Moriarty N, Alam M, Kalus A, O'Connor K (December 2019). "Current understanding and approach to delusional infestation". Am. J. Med. (Review). 132 (12): 1401–1409. doi:10.1016/j.amjmed.2019.06.017. PMID 31295443. S2CID 195893551.
4. ^ a b Kemperman PM, Vulink NC, Smit C, Hovius JW, de Rie MA (July 2024). "Review of literature and clinical practice experience for the therapeutic management of Morgellons disease". J Eur Acad Dermatol Venereol. 38 (7): 1300–1304. doi:10.1111/jdv.19831. PMID 38308572.
5. ^ a b c d e f g h i j k l m n o p q r s Suh KN (June 7, 2018). "Delusional infestation: Epidemiology, clinical presentation, assessment and diagnosis". UpToDate. Wolters Kluwer. Retrieved March 8, 2020.
6. ^ McPhie ML, Kirchhof MG (March 2022). "A systematic review of antipsychotic agents for primary delusional infestation". J Dermatolog Treat. 33 (2): 709–721. doi:10.1080/09546634.2020.1795061. PMID 32658556.
7. ^ Ahmed A, Affleck AG, Angus J, et al. (October 2022). "British Association of Dermatologists guidelines for the management of adults with delusional infestation 2022". Br J Dermatol. 187 (4): 472–480. doi:10.1111/bjd.21668. PMID 35582951.
8. ^ a b c d e f g h i j k l m n o p q r s Reich A, Kwiatkowska D, Pacan P (December 2019). "Delusions of parasitosis: an update". Dermatology and Therapy (Review). 9 (4): 631–638. doi:10.1007/s13555-019-00324-3. PMC 6828902. PMID 31520344.
9. ^ Lutfi Al-Imam AM (January 2016). "A systematic literature review on delusional parasitosis". Journal of Dermatology & Dermatologic Surgery (Review). 20 (1): 5–14. doi:10.1016/j.jdds.2015.11.003.
10. ^ a b c d e f g Campbell EH, Elston DM, Hawthorne JD, Beckert DR (May 2019). "Diagnosis and management of delusional parasitosis". Journal of the American Academy of Dermatology (Review). 80 (5): 1428–1434. doi:10.1016/j.jaad.2018.12.012. PMID 30543832. S2CID 56483906.
11. ^ Hylwa SA, Bury JE, Davis MD, Pittelkow M, Bostwick JM (September 2011). "Delusional infestation, including delusions of parasitosis: results of histologic examination of skin biopsy and patient-provided skin specimens". Archives of Dermatology. 147 (9): 1041–1045. doi:10.1001/archdermatol.2011.114. PMID 21576554.
12. ^ Fisher, Alec H.; Stanciu, Cornel N. (December 2017). "Amphetamine-Induced Delusional Infestation". American Journal of Psychiatry Residents' Journal. 12 (12): 12–13. doi:10.1176/appi.ajp-rj.2017.121204.
13. ^ Hinkle NC (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.
14. ^ Assalman I, Ahmed A, Alhajjar R, Bewley AP, Taylor R (December 2019). "Treatments for primary delusional infestation". The Cochrane Database of Systematic Reviews. 12 (12): CD011326. doi:10.1002/14651858.CD011326.pub2. PMC 6903768. PMID 31821546.
15. ^ Harth W, Hermes B, Freudenmann RW (April 2010). "Morgellons in dermatology". Journal der Deutschen Dermatologischen Gesellschaft (Case report and review). 8 (4): 234–242. doi:10.1111/j.1610-0387.2009.07219.x. PMID 19878403. S2CID 205857564.
16. ^ Heller MM, Wong JW, Lee ES, et al. (July 2013). "Delusional infestations: clinical presentation, diagnosis and treatment". International Journal of Dermatology (Review). 52 (7): 775–783. doi:10.1111/ijd.12067. PMID 23789596. S2CID 205187385.
17. ^ a b Hinkle NC (June 2011). "Ekbom syndrome: a delusional condition of "bugs in the skin"". Current Psychiatry Reports. 13 (3): 178–186. doi:10.1007/s11920-011-0188-0. PMID 21344286. S2CID 524974.
18. ^ a b Freudenmann RW, Lepping P (October 2009). "Delusional infestation". Clinical Microbiology Reviews (Review). 22 (4): 690–732. doi:10.1128/cmr.00018-09. PMC 2772366. PMID 19822895.
19. ^ Slaughter JR, Zanol K, Rezvani H, Flax J (December 1998). "Psychogenic parasitosis. A case series and literature review". Psychosomatics (Historical review and case report). 39 (6): 491–500. doi:10.1016/S0033-3182(98)71281-2. PMID 9819949.
20. ^ Ekbom KA, Yorston G, Miesch M, Pleasance S, Rubbert S (June 2003). "The pre-senile delusion of infestation". History of Psychiatry (Historical biography). 14 (54 Pt 2): 229–256. doi:10.1177/0957154X030142007. PMID 14521159. S2CID 444986.
21. ^ Harlan C (July 23, 2006). "Mom fights for answers on what's wrong with her son". Pittsburgh Post-Gazette. Retrieved August 4, 2007.
22. ^ DeVita-Raeburn E (March–April 2007). "The Morgellons mystery". Psychology Today. Retrieved May 8, 2015.
23. ^ Browne T (1690). "A Letter to a Friend". James Eason, University of Chicago.
24. ^ Schulte B (January 20, 2008). "Figments of the Imagination?". Washington Post Magazine. p. W10. Retrieved June 9, 2008.
25. ^ "Unexplained dermopathy (aka "Morgellons"), CDC Investigation". Centers For Disease Control. November 1, 2007. Archived from the original on June 3, 2016. Retrieved May 9, 2011.
26. ^ Pearson ML, Selby JV, Katz KA, et al. (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. ^ a b Lockwood, Jeffrey (2013). The Infested Mind: Why Humans Fear, Loathe, and Love Insects. Oxford University Press. pp. 101–2. ISBN 978-0199930197.
28. ^ Traver J (February 1951). "Unusual scalp dermatitis in humans caused by the mite, Dermatophagoides (Acarina, epidermoptidae)" (PDF). Proceedings of the Entomological Society of Washington. 53 (1).
29. ^ Hinkle NC (2000). "Delusory parasitosis". American Entomologist. 46 (1): 17–25. doi:10.1093/ae/46.1.17.
30. ^ a b c Shelomi M (June 2013). "Mad scientist: the unique case of a published delusion". Science and Engineering Ethics. 19 (2): 381–388. doi:10.1007/s11948-011-9339-2. PMID 22173734. S2CID 26369401 - via Academia.edu.
31. ^ Poorbaugh JH (June 1993). "Cryptic arthropod infestations: separating fact from fiction" (PDF). Bulletin of the Society for Vector Ecology. 18 (1): 3–5. ISSN 0146-6429. Archived from the original (PDF) on 2017-12-15. Retrieved 2020-08-04.
32. ^ Shelomi M (June 2013). "Evidence of photo manipulation in a delusional parasitosis paper". The Journal of Parasitology. 99 (3): 583–585. doi:10.1645/12-12.1. PMID 23198757. S2CID 6473251.

Classification|

* ICD-11: MB26.09
* ICD-10: F22
* ICD-9-CM: 297.1
* MeSH: D063726
* DiseasesDB: 9622

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