AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Delusions of parasitosis (DP) 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 DP is complicated. It is considered primarily a monosymptomatic hypochondriacal psychosis and has been associated with schizophrenia, obsessional states, bipolar disorder, depression, and anxiety disorders. DP occurs primarily in white middle-aged or older women, although it has been reported in all age groups and in men.

Medscape Resource Centers for Schizophrenia, Bipolar Disorder, Depression, and Anxiety Disorders may provide helpful additional information.

Savely et al¹ 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 DP. Koblenzer² and Waddell and Burke³ have discussed the utility of the term, with Murase et al⁴ finding the term useful for building a therapeutic alliance with patients with DP. The Centers for Disease Control and Prevention is currently investigating Morgellon disease.⁵

William Harvey⁶ 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.

Pathophysiology

The cause of DP 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.

Frequency

United States

The exact prevalence of DP is unknown.

International

The exact prevalence of DP is unknown.

Mortality/Morbidity

The literature includes one report of suicide in a 40-year-old man with DP.⁸

Race

DP appears to be more common in whites than in people of other races.

Sex

DP occurs primarily in white middle-aged or older women, although it 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

This disease is more common in middle-aged and elderly persons than in others. The male-to-female ratio is 1:1 in people younger than 50 years and 3:1 in those older than 50 years.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

Patients must be queried about their symptoms, the duration of symptoms, and their belief about the etiology. Notably, Goddard⁹ has described a seasonality to DP.

The diagnosis and treatment of DP can be an involved clinical activity. Patients with DP can resist suggestions that their condition is psychiatric rather than physical and refuse referrals for psychiatric care. In fact, in 35% of patients, the belief of infestation is unshakable. In approximately 12% of patients, the delusion of infestation is shared by a significant other. This phenomenon is known as folie à deux (eg, craziness for 2) or folie partagé (ie, shared delusions). Variations in this are the conviction that a child, a spouse, or a pet is infested.

DP is a monosymptomatic psychosis, a type of psychopathology relatively distinct from the remainder of the personality. If the condition has a defined pathologic or external cause (eg, scabies) it is not truly DP. In investigating the history of a patient with such suspected delusions, other causes of itch must be investigated. To diagnose this condition, true infestations (eg, scabies), pediculosis, and primary systemic causes of pruritus must be excluded. Examples include hepatitis, HIV infection, dermatitis herpetiformis, thyroid disease, anemia, renal dysfunction, neurologic dysfunction, and lymphoma.

DP is distinct from formication. Formication involves the cutaneous sensation of crawling, biting, and stinging. Formication does not involve the fixed conception that skin sensations are induced by parasites. Patients with this condition can accept proof that they do not have an infestation. Many cases of formication remain idiopathic.

Mimics of DP

Other forms of psychiatric illness can mimic DP. Such psychiatric illnesses are accompanied by signs of mental illness.

For example, patients with schizophrenia may think they are being attacked by insects as a manifestation of their paranoia.

A type of severe depression termed psychotic depression may cause the patient to believe he or she is contaminated or "dirty" because of insect infestation. Such a patient may have a depressed mood and a sense of helplessness, hopelessness, worthlessness, or excessive guilt. Often, these feelings are obvious at clinical presentation.¹⁰

Drug-induced delusions of parasitosis have been reported during treatment for Parkinson disease.¹¹

Steinert and Studemund¹² reported a 45-year-old man who did not have a history of psychological pathology, who, after ingesting ciprofloxacin to treat an infection, was overcome with acute delusional parasitosis. He stopped taking the ciprofloxacin, and the DP resolved altogether without utilization of an antipsychotic agent. Cases in which an etiology is defined are best classified as secondary DP.

Guarneri et al¹³ noted a patient who was thought to have DP but who, in fact, had infestation with Limothrips cerealium; they termed the condition pseudo-delusory syndrome (ie, infestation with an uncommon insect).

Ghaffari-Nejad and Toofani¹⁴ noted a case of secondary DP in a patient with major depressive disorder who had delusions of oral parasitosis; the patient sensed lizards and small organisms in her mouth.

Physical

Patients with DP create their skin rash. They can present with no findings, erosions or ulcers with or without crusts or prurigo nodularis. They may evidence a dermatitis related to attempted treatments, which may include irritating or corrosive cleansers or harsh abrasive devices.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Internal disease
Lymphoma
Cocaine-Related Psychiatric Disorders

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• No laboratory test can help in diagnosing DP; however, laboratory tests can help identify other diseases that can mimic DP.
• To exclude infestation, a mineral oil preparation should be used to eliminate scabies, and a microscopic examination of skin and hair should be performed to exclude louse infestation.
• • Neurologic pathology due to toxins or vitamin deficiencies can be evaluated with the appropriate tests.
  • Tests to assess other causes of pruritus (eg, low iron level, liver or kidney disease) can be performed if clinically indicated. Examples include evaluation of the complete blood cell count; urinalysis; liver function tests; thyroid function tests; and determinations of levels of serum electrolytes and glucose, blood urea nitrogen, serum creatinine, serum vitamin B-12, folate, and iron.
  • Unless dermatitis herpetiformis needs to be excluded, skin biopsy is usually more useful to reassure patients of the lack of pathology than to diagnose DP.
  • Use of cocaine, methylphenidate, or amphetamines must be ascertained, and if occurring, it should be stopped.
  • It is useful to examine the "proof" that the patient brings in so that one may truthfully say that the material was examined and no parasites were found. One authority anecdotally relates how he found ants in the debris and, after explaining that these arthropods did not live on or in humans, was able to give practical advice to reduce the problem.

Imaging Studies

• In rare cases, neurologic impairment (eg, tumors, neuritis, multiple sclerosis) can mimic the symptoms of DP.
• Causes of such impairment should be excluded with MRI or CT scanning if they are strongly suspected on the basis of the clinical findings.

Histologic Findings

DP has no specific histologic findings. All skin changes are secondary to rubbing, scratching, picking, or other treatment attempts.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

The only clear method to clear the delusion that underlies DP is the administration of psychotropic medications. However, the disease can remit on its own. If the sensation of itch is related to some actual disease or substance use rather than a monosymptomatic hypochondriacal psychosis, the disease can be treated, or the substance inducing the sensation can be eliminated.

It is vitally important that the practitioner does not "use the delusion" to encourage the patient to accept certain treatments. While getting the patient to take a medication, such as risperidone, may help the condition, telling them that it is a medication that "kills the parasites", reinforces and validates the delusion. Even giving the patient a course of topical permethrin "just in case" may strengthen the delusion and make it that much more difficult later on. Every DP patient can recount the visit on which his or her suspicions of infestation were "confirmed."

Serotonergic antidepressants may have a role in the treatment of these patients.^{15, 16}

Reichenberg et al¹⁷ reported on a patient whose DP was cured overnight by having him stop taking cetirizine and doxepin (25 mg), as well as any over-the-counter medications.

Rocha and Hara¹⁸ reported that aripiprazole at 15 mg for 8 weeks and then 7.5 mg/d was effective for DP treatment. They stated:

Aripiprazole has a unique pharmacologic profile that is different from other atypical antipsychotic drugs. It is  considered a partial dopaminergic agonist acting on both postsynaptic dopamine D2 receptors and presynaptic autoreceptors. It acts as a weak stimulator (so-called “partial” agonist) at dopamine D2 receptors, with the potential for exerting either antagonistic (inhibitory) or agonistic (stimulating) effects, depending on the sensitivity of the receptors and availability of dopamine, its natural agonist in the brain. In addition, aripiprazole displays partial agonism at serotonin (1A) receptors and antagonism at serotonin (2A) receptors.

• Had seen at least one patient with DP - 84.7%
• Had 1-2 cases of DP over the preceding 5 years - 33%
• Had seen 3-5 such patients over the preceding 5 years - 28%
• Had diagnosed no cases of DP during the past 5 years - 23%
• Had more than 10 patients with DP over the past 5 years - 7%
• Were currently treating a patient with DP - 20%
• Always request a psychiatric opinion about their patients with DP - 40.75%
• Often ask for a psychiatric opinion about their patients with DP 28.8%
• Use their own pharmacological treatment, mostly sedatives and anxiety-relieving drugs - 15.3%. 

Consultations

A psychiatrist should be consulted if the dermatologist cannot or will not prescribe the necessary medications. Most patients with DP are reluctant to see a psychiatrist, and the dermatologist may be more successful in giving the referral if they have gained the patient's trust after several clinic visits instead of immediately after meeting the patient.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

The current treatment of choice is risperidone^{20, 21} or olanzapine.²² The older treatment of choice is pimozide.²³

The most common adverse effects of pimozide are extrapyramidal symptoms, including stiffness and, occasionally, a special inner sense of restlessness called akathisia. Effective treatment of such extrapyramidal reactions includes benztropine 1-2 mg up to 4 times daily as needed or diphenhydramine 25 mg 3 times daily.

Drug Category: Antipsychotics

Used to treat psychoses.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Outpatient Care

• After medication has cleared the DP, it should be continued for several months and then discontinued.
• Often, patients come to think that the medication has killed the bugs, and many (but not all) have a remission of their delusions.

Complications

• If DP is not treated, scarring can result. The patient's entire life and family may be disrupted by their distress and attempts at treatment.
• Therapy for DP can cause adverse effects.
• • Pimozide can result in tardive dyskinesia and akathisia.
  • Extrapyramidal reactions have been reported to occur in approximately 10-15% of patients taking pimozide.
  • Pimozide can have cardiotoxic effects at high doses. It may cause ECG changes such as prolongation of the QT interval, T-wave changes, and the appearance of U waves.
• Lim et al²⁴ noted an incidence of camphor-related, self-inflicted keratoconjunctivitis secondary to DP.

Prognosis

• Many patients with DP 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.

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 DP.
• 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."
• For excellent patient education resources, visit eMedicine's Mental Health and Behavior Center.
• Medscape's Patient-Provider Relations in Psychiatry & Mental Health Resource Center may provide additional helpful informaiton.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• DP is a real entity, and untreated patients pick at themselves, causing scarring. Although attempts to stop this behavior are often unsuccessful, they should be made anyway to prevent morbidity.
• The diagnosis is one of exclusion, and other diseases that can also cause a sensation of itching (eg, internal disease, actual infestation) must be considered, investigated, and treated if present.
• Adverse effects of pimozide and other psychiatric medications must be discussed in a manner that patients are informed of the risks but not deterred from therapy.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

1. Savely VR, Leitao MM, Stricker RB. The mystery of Morgellons disease: infection or delusion?. Am J Clin Dermatol. 2006;7(1):1-5. [Medline].
2. Koblenzer CS. The challenge of Morgellons disease. J Am Acad Dermatol. Nov 2006;55(5):920-2. [Medline].
3. Waddell AG, Burke WA. Morgellons disease?. J Am Acad Dermatol. Nov 2006;55(5):914-5. [Medline].
4. Murase JE, Wu JJ, Koo J. Morgellons disease: a rapport-enhancing term for delusions of parasitosis. J Am Acad Dermatol. Nov 2006;55(5):913-4. [Medline].
5. Marris E. Mysterious 'Morgellons disease' prompts US investigation. Nat Med. Sep 2006;12(9):982. [Medline].
6. Harvey WT. Morgellons disease. J Am Acad Dermatol. Apr 2007;56(4):705-6. [Medline].
7. Walling HW, Swick BL. Psychocutaneous syndromes: a call for revised nomenclature. Clin Exp Dermatol. May 2007;32(3):317-9. [Medline].
8. Monk BE, Rao YJ. Delusions of parasitosis with fatal outcome. Clin Exp Dermatol. Jul 1994;19(4):341-2. [Medline].
9. Goddard J. Seasonality of delusions of parasitosis. J Agromedicine. 2003;9(1):23-6. [Medline].
10. Koo J, Lee CS. Delusions of parasitosis. A dermatologist's guide to diagnosis and treatment. Am J Clin Dermatol. 2001;2(5):285-90. [Medline].
11. Swick BL, Walling HW. Drug-induced delusions of parasitosis during treatment of Parkinson's disease. J Am Acad Dermatol. Dec 2005;53(6):1086-7. [Medline].
12. Steinert T, Studemund H. Acute delusional parasitosis under treatment with ciprofloxacin. Pharmacopsychiatry. Jul 2006;39(4):159-60. [Medline].
13. Guarneri F, Guarneri C, Mento G, Ioli A. Pseudo-delusory syndrome caused by Limothrips cerealium. Int J Dermatol. Mar 2006;45(3):197-9. [Medline].
14. Ghaffari-Nejad A, Toofani K. Delusion of oral parasitosis in a patient with major depressive disorder. Arch Iran Med. Jan 2006;9(1):76-7. [Medline].
15. Scheinfeld N. Delusions of parasitiosis: a case with a review of its course and treatment. Skinmed. Nov-Dec 2003;2(6):376-8. [Medline].
16. Wenning MT, Davy LE, Catalano G, Catalano MC. Atypical antipsychotics in the treatment of delusional parasitosis. Ann Clin Psychiatry. Sep-Dec 2003;15(3-4):233-9. [Medline].
17. Reichenberg JS, Magid M, Drage LA. A cure for delusions of parasitosis. J Eur Acad Dermatol Venereol. Nov 2007;21(10):1423-4. [Medline].
18. Rocha FL, Hara C. Aripiprazole in delusional parasitosis: Case report. Prog Neuropsychopharmacol Biol Psychiatry. Apr 13 2007;31(3):784-6. [Medline].
19. Szepietowski JC, Salomon J, Hrehorów E, Pacan P, Zalewska A, Sysa-Jedrzejowska A. Delusional parasitosis in dermatological practice. J Eur Acad Dermatol Venereol. Apr 2007;21(4):462-5. [Medline].
20. Elmer KB, George RM, Peterson K. Therapeutic update: use of risperidone for the treatment of monosymptomatic hypochondriacal psychosis. J Am Acad Dermatol. Oct 2000;43(4):683-6. [Medline].
21. Friedmann AC, Ekeowa-Anderson A, Taylor R, Bewley A. Delusional parasitosis presenting as folie à trois: successful treatment with risperidone. Br J Dermatol. Oct 2006;155(4):841-2. [Medline].
22. Meehan WJ, Badreshia S, Mackley CL. Successful treatment of delusions of parasitosis with olanzapine. Arch Dermatol. Mar 2006;142(3):352-5. [Medline].
23. van Vloten WA. Pimozide: use in dermatology. Dermatol Online J. Mar 2003;9(2):3. [Medline].
24. Lim GC, Chen YF, Liu L, Huang SC, Lin KK, Hsiao CH. Camphor-related self-inflicted keratoconjunctivitis complicating delusions of parasitosis. Cornea. Dec 2006;25(10):1254-6. [Medline].
25. Aw DC, Thong JY, Chan HL. Delusional parasitosis: case series of 8 patients and review of the literature. Ann Acad Med Singapore. Jan 2004;33(1):89-94. [Medline].
26. Bourée P, Benattar B, Périvier S. Ekbom syndrome or delusional parasitosis. Rev Prat. 2007 Mar 31;57(6):585-9. Review. [Medline].
27. Donabedian H. Delusions of Parasitosis. Clin Infect Dis. Oct 19 2007;45(11):[Medline].
28. Edison KE, Slaughter JR, Hall RD. Psychogenic parasitosis: a therapeutic challenge. Mo Med. Mar-Apr 2007;104(2):132-7; quiz 137-8. [Medline].
29. Elkan D. Morgellons disease: real or delusion?. New Scientist. Sep 15 2007;195 (2621):46-9.
30. Freudenmann RW, Schönfeldt-Lecuona C. Delusional parasitosis: treatment with atypical antipsychotics. Ann Acad Med Singapore. Jan 2005;34(1):141-2; author reply 142. [Medline].
31. Gould WM, Gragg TM. Delusions of parasitosis. An approach to the problem. Arch Dermatol. Dec 1976;112(12):1745-8. [Medline].
32. Krauseneck T, Soyka M. Delusional parasitosis associated with pemoline. Psychopathology. Mar-Apr 2005;38(2):103-4. [Medline].
33. Krishnan A, Koo J. Psyche, opioids, and itch: therapeutic consequences. Dermatol Ther. Jul-Aug 2005;18(4):314-22. [Medline].
34. Le L, Gonski PN. Delusional parasitosis mimicking cutaneous infestation in elderly patients. Med J Aust. Aug 18 2003;179(4):209-10. [Medline].
35. Lepping P, Russell I, Freudenmann RW. Antipsychotic treatment of primary delusional parasitosis: systematic review. Br J Psychiatry. Sep 2007;191:198-205. [Medline].
36. Nicolato R, Corrêa H, Romano-Silva MA, Teixeira AL Jr. Delusional parasitosis or Ekbom syndrome: a case series. Gen Hosp Psychiatry. Jan-Feb 2006;28(1):85-7. [Medline].
37. Paquette M. Morgellons: disease or delusions?. Perspect Psychiatr Care. Apr 2007;43(2):67-8. [Medline].
38. Tran TM, Browning J, Dell ML. Psychosis with paranoid delusions after a therapeutic dose of mefloquine: a case report. Malar J. 2006;5:74. [Medline].
39. Wilson FC, Uslan DZ. Delusional parasitosis. Mayo Clin Proc. Nov 2004;79(11):1470. [Medline].
40. Zanol K, Slaughter J, Hall R. An approach to the treatment of psychogenic parasitosis. Int J Dermatol. Jan 1998;37(1):56-63. [Medline].

Article Last Updated: Feb 12, 2008