Delusional parasitosis

Delusional parasitosis
Classification and external resources
ICD-9	300.29
DiseasesDB	9622
eMedicine	derm/939

Delusional parasitosis, or delusory parasitosis, also known as Ekbom's syndrome,^[1][2] is a form of psychosis whose victims acquire a strong delusional belief that they are infested with parasites, whereas in reality no such parasites are present.^[3] Very often the imaginary parasites are reported as allergic reaction to household cleaning supplies; in these cases the experience of the sensation known as formication may provide the basis for this belief.

The false belief of delusional parasitosis stands in contrast to actual cases of parasitosis, such as scabies and infestation with Demodex.^[4][5]

The alternative name of Ekbom's syndrome derives from Swedish neurologist Karl Axel Ekbom,^[6] who published seminal accounts of the disease in 1937 and 1938. It is important not to confuse or interchange this with Willis-Ekbom Disease (or WED), another name for restless legs syndrome (RLS).

Classification

Delusional parasitosis is divided into primary, secondary functional and secondary organic groups.^[7]

Primary

In primary delusional parasitosis, the delusions comprise the entire disease entity, there is no additional deterioration of basic mental functioning or idiosyncratic thought processes. The parasitic delusions consist of a single delusional belief regarding some aspect of health. This is also referred to as "monosymptomatic hypochondriacal psychosis",^[8]:389 and sometimes as "true" delusional parasitosis. In the DSM-IV, this corresponds with "delusional disorder, somatic type".

Secondary functional

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

Secondary organic

Secondary organic delusional parasitosis occurs when the state of the patient is caused by a medical illness or substance (medical or recreational) use. In the DSM-IV this 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 and methamphetamine (as in amphetamine psychosis).^[9] 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.^[9]

Presentation

Details of delusional parasitosis vary among sufferers, but it 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).^[3] 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.^[2][10]

Nearly any marking upon the skin, or small object or particle found on the person or his 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.^[3] This presenting of "evidence" is known as "the matchbox sign" because the "evidence" is frequently presented in a small container, such as a matchbox.^[2]

A study conducted of 108 patients at the Mayo Clinic was published in Archives of Dermatology on May 16, 2011. The study failed to find evidence of skin infestation despite doing skin biopsies and examining specimens provided by the patients. The study, which was conducted between 2001 and 2007, concluded that the feeling of skin infestation was delusional parasitosis.^[11][12]

Delusional parasitosis is seen more commonly in women, and the frequency is much higher past the age of 40.^[2][9]

The peer reviewed Dermatology Online Journal has recently noted a very rare form of delusional parasitosis called delusional tinea.^[13]

Treatment

Treatment of secondary forms of delusional parasitosis are addressed by treating 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.

However, it is also characteristic that sufferers will reject the diagnosis of delusional parasitosis by medical professionals, and very few are willing to be treated, despite demonstrable efficacy of treatment.^[3]

Delusory cleptoparasitosis

Delusory cleptoparasitosis is a form of delusion of parasitosis where the sufferer believes the infestation is in their dwelling, rather than on or in their body.^[14]

Morgellons

The term "Morgellons" was introduced by Mary Leitao in 2004 to describe a skin condition characterized by a range of cutaneous (skin) symptoms including crawling, biting, and stinging sensations; finding fibers on or under the skin; and persistent skin lesions (e.g., rashes or sores). A majority of health professionals, including most dermatologists, regard Morgellons as a manifestation of other known medical conditions, including delusional parasitosis^[15][16][17] and believe any fibers found are from textiles such as clothing.^[18] The Morgellons Research Foundation, a non-profit advocacy organization, believes that it is a new infectious disease that will be confirmed by future research.^[19][20] "Other health professionals don't acknowledge Morgellons disease or are reserving judgment until more is known about the condition".^[21] Separate, large-scale studies into the proposed diagnosis by the Centers for Disease Control and Prevention (CDC)^[22][23] and the Mayo Clinic^[11][12][24] failed to find an infectious cause of the symptoms and confirmed that Morgellons is a variant of delusional parasitosis. The term "delusional infestation" has been suggested to account for Morgellons' patients as well as standard delusional parasitosis patients.

In popular culture

The film Hellraiser II has a scene with a mental patient with this condition, who is "prescribed" a straight razor to "remedy" his condition.

In season 3 episode 12 of the television show The X-Files, Scully mentions this condition in conversation with Mulder.

In season 5 episode 7 of the television show House, Dr. Wilson diagnoses Dr. House as having delusional parasitosis.

The animated series The Simpsons makes reference to delusional parasitosis in the motto of the Springfield Psychiatric Center: "Because There May Not Be Bugs On You".

The Philip K. Dick novel A Scanner Darkly contains a character named Jerry Fabin who suffers from intense delusional parasitosis. This detail forms the partly humorous plot of the opening segment of the film adaptation of the story.

The play Bug and subsequent film adaptation are about a couple who experience delusional parasitosis together.

In Scott Sigler's novels Infected and Contagious, skin infestations by alien parasites are discounted as delusional parasitosis, specifically Morgellons.

In the first issue of the comic book Hellblazer, John Constantine's friend believes he is experiencing delusional parasitosis as a result of being a junkie. (As it turns out, he really is covered in insects.)

In Neil Gaiman's The Sandman, Delirium inflicts a curse on a policeman, giving him delusional parasitosis.

In the Dark Skies episode “The Last Wave,” two characters hallucinate insects under their skin as a result of actually having alien bacteria in their bodies.

The sound novel Higurashi no Naku Koro Ni features a character who experienced delusional parasitosis and was driven to self-mutilation, believing maggots were mixed in with her blood and would try to crawl back inside her through the open wounds.

In the Korean film Oldboy, the protagonist is seen hallucinating about ants crawling on his skin as a result of psychosis brought on by his solitary confinement.

In the fantasy roleplaying game Dungeons and Dragons characters who come into contact with a type of demon called an 'Ekolid' develop this delusion.

In Season 10, Episode 4 ("The Itch") of the television show Criminal Minds (2014), the unsub has delusional parasitosis, and kills his victims when they don't support his delusion.

See also

• Cutaneous conditions
• List of cutaneous conditions
• Stimulant psychosis

References

Further reading

• Berrios GE (1985). "Delusional Parasitosis and Physical Disease". Comprehensive Psychiatry 26 (5): 395–403. doi:10.1016/0010-440X(85)90077-X. PMID 4028691. 
• Frances A, Munro A (1989). "Treating a woman who believes she has bugs under her skin". Hospital and Community Psychiatry 40 (11): 1113–1114. PMID 2807218. 
• Goddard J (1995). "Analysis of 11 cases of delusions of parasitosis reported to the Mississippi Department of Health". Southern Medical Journal 88 (8): 837–839. doi:10.1097/00007611-199508000-00008. PMID 7631209. 
• Gould WM, Gragg TM (1976). "Delusions of parasitosis". Archives of Dermatology 112 (12): 1745–1748. doi:10.1001/archderm.1976.01630370033007. PMID 1008566. 
• Morris M (1991). "Delusional Manifestation". The British Journal of Psychiatry 159: 83–87. doi:10.1192/bjp.159.1.83. 
• Rasmussen JE; Voorhees, JJ (1990). "Psychosomatic Dermatology". Archives of Dermatology 126 (1): 90–93. doi:10.1001/archderm.1990.01670250096016. PMID 2404467. 
• Schrut AH, Waldron WG (1963). "Psychiatric and entomological aspects of delusory parasitosis". JAMA 186 (4): 429–430. doi:10.1001/jama.1963.63710040008018b. 
• Ekbom K, Yorston G, Miesch M, Pleasance S, Rubbert S (2003). "The pre-senile delusion of infestation". Hist Psychiatry 14 (54 Pt 2): 229–232. doi:10.1177/0957154X030142007. PMID 14521159. 
• Slaughter, JR; Zanol, K; Rezvani, H; Flax, J (December 1998). "Psychogenic Parasitosis". Psychosomatics 39 (6): 491–500. doi:10.1016/S0033-3182(98)71281-2. PMID 9819949. 

External links

• The Bohart Museum of Entomology; Human Skin Parasites & Delusional Parasitosis
• medical dictionary definitions of Ekbom's syndrome