Freudenmann, R.W.

Huber, M.

Lepping, P.

English

Bangor University: eBangor / Prifysgol Bangor

How to approach delusional infestation

P. Lepping

M. Huber

R. W. Freudenmann

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Bangor University Research Portal

   PRIFYSGOL BANGOR / BANGOR UNIVERSITY  How to approach delusional infestationLepping, P.; Huber, M.; Freudenmann, R.W.BMJ OpenDOI:10.1136/bmj.h1328Published: 01/04/2015Publisher's PDF, also known as Version of recordCyswllt i'r cyhoeddiad / Link to publicationDyfyniad o'r fersiwn a gyhoeddwyd / Citation for published version (APA):Lepping, P., Huber, M., & Freudenmann, R. W. (2015). How to approach delusional infestation.BMJ Open, Article Number h1328. https://doi.org/10.1136/bmj.h1328Hawliau Cyffredinol / General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/orother copyright owners and it is a condition of accessing publications that users recognise and abide by the legalrequirements associated with these rights.            • Users may download and print one copy of any publication from the public portal for the purpose of privatestudy or research.            • You may not further distribute the material or use it for any profit-making activity or commercial gain            • You may freely distribute the URL identifying the publication in the public portal ?Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access tothe work immediately and investigate your claim. 11. May. 2021PRACTICE POINTERHow to approach delusional infestationPeter Lepping consultant psychiatrist; honorary professor 1, Markus Huber consultant psychiatrist 2,Roland W Freudenmann consultant psychiatrist; associate professor 31Betsi Cadwaladr University Health Board, North Wales, Wrexham, UK; Centre for Mental Health and Society, Bangor University, Bangor, UK;Mysore Medical College and Research Institute, Mysore, India; 2Department of Psychiatry, General Hospital Bruneck, South Tyrol, Italy; 3Departmentof Psychiatry and Psychotherapy III, University of Ulm, Ulm, GermanyDelusional infestation (previously also known as delusionalparasitosis or Ekbom’s syndrome) is a rare disorder, but itcommonly poses disproportionate practical problems tohealthcare systems.1 It is characterised by a patient’s fixed beliefthat his or her skin, body, or immediate environment is infestedby small, living (or less often inanimate) pathogens despite thelack of any medical evidence for this.1 Delusional infestation isneither a single disease nor a single diagnostic entity. The classicform, primary delusional infestation, develops without anyknown cause or underling illness and meets criteria for apersistent delusional disorder (ICD-10 (internationalclassification of diseases, 10th revision)) or delusional disordersomatic type (DSM-5 (Diagnostic and Statistical Manual ofMental Disorders, fifth edition)). Approximately 60% ofpatients, however, have secondary forms of delusionalinfestation2 that occur in the context of substance misuse (suchas cocaine, amphetamines, cannabis), dopaminergicmedications,antibiotics, or during physical or psychiatric illnesses (such asdelirium, dementia, depression, schizophrenia, stroke, and othermedical conditions that affect the brain or cause pruritus).1 2The neurobiology of delusional infestation is not fullyunderstood. Studies point to dysfunction or structural braindamage in the frontal cortex, the dorsal striatum, parietal andtemporal cortex, and the thalamus—that is, brain areas involvedin judgment, body sensation, and learning.3 This supports thehypothesis that the delusional beliefs are the result of disturbedbasic learning processes and of errors of probabilistic reasoning(favouring the unlikely explanation over the likely).4How does delusional infestation present?Patients complain about being infested with known pathogenssuch as insects or worms, or pathogens hitherto unknown tomedical science (such as “Morgellons,” fibres, or strands).5 6Additional symptoms are abnormal sensations on or underneaththe skin (itching, stinging, biting), which patients explain bypathogens living, eating, breeding, and building nests in theirbody. The alleged infestation often includes the patient’simmediate environment (room, house, car, etc). Patients oftenspend hours each day examining the alleged pathogens andtrying to catch them; if “successful,” they often take or sendspecimens of these pathogens to physicians or laboratories asproof of infestation. This phenomenon is called “the specimensign.”1 7 It is not sufficient to diagnose delusional infestation,and case series report frequencies between 29% and 74%.6-8 Thesearch for the pathogen can absorb much of a patient’s time andputs a huge disease burden on patients and their families.Sometimes the delusional belief spreads to significant others asa shared psychotic disorder (5-15%,2 4%,7 26%9). Rarely,delusional infestation also occurs as a proxy syndrome—thatis, a person (who is the real patient) assumes symptoms ofdelusional infestation in his or her children or pets but does notcomplain about being infested him/herself. In double delusionalinfestation, patients complain of symptoms in addition tosymptoms in a child or pet.10How common is delusional infestation?Delusional infestation is rare, with an incidence of 1.9 in 100000 person years, but recent studies indicate a growingfrequency.11 It occurs in all ages, but middle aged and olderwomen prevail (with the exception of delusional infestationinduced by illicit drugs in young men).2 7 9 11How is delusional infestation diagnosed?Delusional infestation is a diagnosis of exclusion. The startingpoint is usually a patient with a fixed conviction of beinginfested, for whom we suggest the following approach:• Ask why the patient is convinced that they are infested andwith what. Explore how fixed this belief is—would theyconsider alternative explanations for their symptoms?• Distinguish these beliefs from formication (the sensationof insects crawling on or underneath the skin), which is aCorrespondence to: P Lepping peter.lepping@wales.nhs.ukFor personal use only: See rights and reprints http://www.bmj.com/permissions Subscribe: http://www.bmj.com/subscribeBMJ 2015;350:h1328 doi: 10.1136/bmj.h1328 (Published 1 April 2015) Page 1 of 3PracticePRACTICEThe bottom line• Consider delusional infestation in patients who present with a fixed belief that they are infested with living or non-living organisms inthe absence of medical evidence for this• Always exclude real infestations first, with examination, review by a dermatologist or infectious disease specialist, and appropriatetests• Acknowledge the patient’s distress without reinforcing false beliefs• Most patients require antipsychotic treatment (amisulpride, olanzapine, or risperidone), which may be offered as a means to alleviatesymptoms• Management ideally requires a multidisciplinary approach, but, as patients rarely agree to full psychiatric assessment, physicians whohave engaged patients in a trusting relationship should offer medication, if possible with psychiatric adviceMethodsThis review is based on a comprehensive review of the subject we published in 20091 and other publications since. The evidence primarilycomes from analyses of case series, prevalence, and imaging studies.known symptom of menopause and is not accompanied byfixed delusions.• Exclude real infestations in all cases, even if a patient’sbizarre explanation of the symptoms makes delusionalinfestation easy to recognise.1 Examine the patient and anyspecimens they bring. Rigorous exclusion of an infestationby a dermatologist or infectious disease specialist is usuallyindicated.• Check for triggering or contributing factors. For instance:- Ask about recent new medication (especially antibioticsor stimulants) and drug use. Formication without delusionalinfestation may occur in acute intoxication with stimulants(“cocaine bug”), in which case it subsides with haloperidolor spontaneously when the intoxication ends.- Ask about symptoms of anxiety and depression, whichcommonly coincide.12 Consider other psychiatricconditions, such as dementia with delirium orschizophrenia.- Consider medical and neurological conditions, especiallyif they cause itching, as they may lead the patient todevelop delusional infestation. These include diabetes,cancer, stroke, and thyroid diseases.• Request investigations that a dermatologist ormicrobiologist would find reasonable and necessary.- Some laboratory tests are mandatory: full blood count,especially to look for raised eosinophils (suggestingparasitosis or other infection, allergy, or hypersensitivity);erythrocyte sedimentation rate; C reactive protein; serumcreatinine and electrolytes; liver function; thyroidstimulating hormone; fasting glucose; and ideally urineanalysis to test for illicit drug use.- In some clinical contexts consider other tests, such asserology for borrelia, treponema, hepatitis, and HIVinfection; vasculitis screening; allergy testing; vitamin B12and folate levels.If all investigations are uneventful and the patient has thedefining symptoms of a delusional illness, the diagnosis ofdelusional infestation can be made. In this case stop furtherinvestigations in order not to reinforce the delusion, except foradditional specimens the patient may bring.What is the next step?Organising meaningful psychiatric treatment in this patientgroup is often challenging, because most patients will not acceptthe possibility of a psychiatric problem. Delusional infestationrequires management strategies that differ from other psychiatricdisorders to help these patients. Observational data suggest thatspecialised outpatient clinics where a psychiatrist and adermatologist or tropical disease physician see the patienttogether can achieve good adherence.13 However, this wouldrequire further investment, as few such services existworldwide.1 12 13 Because of patients’ reluctance to seepsychiatrists, it will mostly fall to general practitioners ordermatologists to have the discussion about the nature of thesymptoms with a patient and cautiously discuss effectivetreatment options. The doctor who first sees the patient maywant to discuss the case with the local psychiatric team toestablish the diagnosis, develop a treatment plan, and start drugtreatment.Engage the patient when discussing thecondition and its managementThis is essential in any setting and for any form of delusionalinfestation, using an empathic and non-judgmentalapproach.1 14 15 Box 1 outlines useful ways to do so.Engage relatives or friends, with the patient’sconsentThis can be useful in reinforcing treatment aims andinterpretation of symptoms for the patient.Risk assessmentPatients may put themselves or others at risk with the use ofchemicals on their skin or because of suicidal ideation. Thisrequires appropriate risk assessment and sometimes the use ofinvoluntary admissions undermental health legislation accordingto local laws. Look for signs of depression and suicidal ideation.Evaluate risk to others:• “Do you think your child(ren) are infested?”• “Are there other people close to you who think they areinfested or that you think are infested (although doctorsfailed to find a pathogen)?”As with any chronic condition, patients with a long history ofdelusional infestation may develop psychological sequelae suchas depression or anxiety, which may benefit from earlyrecognition and support from local primary care services.12Which medications should we use?Transient episodes of delusional infestation, such as duringintoxications or delirium,may subside spontaneously. DelusionalFor personal use only: See rights and reprints http://www.bmj.com/permissions Subscribe: http://www.bmj.com/subscribeBMJ 2015;350:h1328 doi: 10.1136/bmj.h1328 (Published 1 April 2015) Page 2 of 3PRACTICEBox 1: Discussing delusional infestation and its management with patients1 15 16• Acknowledge the patient’s suffering (such as, “I can see these symptoms are distressing you”). Show empathy and offer to help toreduce distress.• Paraphrase the symptoms (“your itch(ing),” “the sensations,” “the crawling on your skin,” etc.) instead of reinforcing them (such as“being infested”) or questioning them.• State that you did not find any pathogens so far, but you are sure that the patient really suffers from his or her perceptions.• Explain that “The itching may be due to an over-activity in the nervous system, which can give people persistent symptoms after realinfestations.”• You may want to “agree to disagree”; this means you acknowledge that the patient has the right to have a different opinion to you,but also that he or she shall acknowledge that you have the same right. You may want to say: “I’d like to find out what causes yoursymptoms, but we need to keep an open mind. Possible options include an infestation, a medical illness, or psychological illnesses.”• You may want to introduce antipsychotics as helpful in alleviating the patient’s distress and itching (due to the antihistaminic componentof many antipsychotics), explaining that it is not given for schizophrenia: for example, “I can see that you are suffering. Would you likeme to prescribe something that may help you feel a bit calmer? I know you do not suffer from schizophrenia, but in our experiencethese medications can be useful to relieve suffering/itching/distress in patients with problems like yours.”• Do not use phrases such as “calm down,” “be happy it’s not infectious,” “it is only psychogenic,” etc, after obtaining negative laboratorytests for infectious processes; these are likely to upset the patient.• Do not directly reinforce the patient’s (false) beliefs. Do not say “Yes, I found [an infestation]” (although you have not) or “Try this wormcure” (although there are no worms).infestation associated with prescribed or illicit drugs usuallyabates when the substance is stopped.For persisting symptoms such as primary delusional infestationor schizophrenia, we advise treating with antipsychotics. Inpsychotic depression manifesting as delusional infestation,antidepressants plus antipsychotics are recommended.1However,no modern antipsychotic is specifically licensed for treatingdelusional infestation.1 There are no guidelines and no clinicaltrials that meet today’s standards, because full informed consentis usually impossible to obtain.1Limited evidence from case series suggests using low doses ofrisperidone (1-2 mg daily), olanzapine (2.5-5 mg daily),amisulpride (200-400 mg daily), or haloperidol (2-5 mgdaily).8 14 Risperidone and olanzapine achieved full or partialremission in 69% and 72% of cases, respectively.8 However,we lack head to head comparisons with larger samples.Antihistaminergic antipsychotics such as quetiapine have showndisappointing results. First generation antipsychotics may leadto more full remissions than newer antipsychotics.17 However,we cannot recommend pimozide for reasons of drug safety,especially because of problems with postural hypotension,extrapyramidal side effects, and QT prolongation.1 8 14 17The best way to approach antipsychotics with patients is bydiscussing them as a means to relieve distressing symptoms(box 1). Make clear that, while these drugs are also used forschizophrenia, there is no suggestion of this diagnosis in thispatient. We recommend a comparison with other medicationssuch as aspirin, which can be given for pain and also incardiovascular conditions.You may want to discuss medication choices with your localpsychiatrist. Response often begins within two weeks.8 Skinlesions are treated symptomatically. Superinfections are commonand may need dermatological treatment in their own right. Noevidence exists on the use of psychological therapies to enableany treatment recommendations.Contributors: All authors meet ICMJE authorship criteria. RWF and PLwrote the article and contributed equally, and MH critically revised it.PL is guarantor for the article.Competing interests: We have read and understood the BMJ policy ondeclaration of interests and have no relevant interests to declare.Provenance and peer review: Commissioned; externally peer reviewed.1 Freudenmann RW, Lepping P. Delusional infestation.Clin Microbiol Rev 2009;22:690-732.2 Trabert W. 100 years of delusional parasitosis. Meta-analysis of 1,223 case reports.Psychopathology 1995;28:238-46.3 Wolf RC, Huber M, Lepping P, et al. Source-based morphometry reveals distinct patternsof aberrant brain volume in delusional infestation. Prog Neuropsychopharmacol BiolPsychiatry 2014;48:112-6.4 Corlett PR, Taylor JR, Wang XJ, et al. Toward a neurobiology of delusions. Prog Neurobiol2010;92:345-69.5 Pearson ML, Selby JV, Katz KA, et al. Clinical, epidemiologic, histopathologic andmolecular features of an unexplained dermopathy. PLoS ONE 2012;7:e29908.6 Hylwa SA, Bury JE, Davis MD, et al. Delusional infestation, including delusions ofparasitosis: results of histologic examination of skin biopsy and patient-provided skinspecimens. Arch Dermatol 2011;147:1041-5.7 Freudenmann RW, Lepping P, Huber M, et al. Delusional infestation and the specimensign: a European multicentre study in 148 consecutive cases. Br J Dermatol2012;167:247-51.8 Freudenmann RW, Lepping P. Second-generation antipsychotics in primary and secondarydelusional parasitosis: outcome and efficacy. J Clin Psychopharmacol 2008;28:500-8.9 Foster AA, Hylwa SA, Bury JE, et al. Delusional infestation: clinical presentation in 147patients seen at Mayo Clinic. J Am Acad Dermatol 2012;67:673.e1-10.10 Lepping P, Rishniw M, Freudenmann RW. Frequency of delusional infestation by proxyand double delusional infestation in veterinary practice: observations from 724 cases. BrJ Psych 2015;206:160-3.11 Bailey CH, Andersen LK, Lowe GC, et al. A population-based study of the incidence ofdelusional infestation in Olmsted County, Minnesota, 1976-2010. Br J Dermatol2014;170:1130-5.12 Hylwa SA, Foster AA, Bury JE, et al. Delusional infestation is typically comorbid with otherpsychiatric diagnoses: review of 54 patients receiving psychiatric evaluation at MayoClinic. Psychosomatics 2012;53:258-65.13 Ahmed A, Bewley A. Delusional infestation and patient adherence to treatment: anobservational study. Br J Dermatol 2013;169:607-10.14 Huber M, Lepping P, Pycha R, et al. Delusional infestation: treatment outcome withantipsychotics in 17 consecutive patients (using standardized reporting criteria). GenHosp Psychiatry 2011;33:604-11.15 Bostwick JM. Taming hornets: the therapeutic relationship in successful treatment ofdelusional infestation. Gen Hosp Psychiatry 2011;33:533-4.16 Lepping P, Freudenmann RW. Delusional parasitosis: a new pathway for diagnosis andtreatment. Clin Exp Dermatol 2008;33:113-7.17 Lepping P, Russell I, Freudenmann RW. Antipsychotic treatment of delusional parasitosis:systematic review. Br J Psychiatry 2007;191:198-205.Cite this as: BMJ 2015;350:h1328© BMJ Publishing Group Ltd 2015For personal use only: See rights and reprints http://www.bmj.com/permissions Subscribe: http://www.bmj.com/subscribeBMJ 2015;350:h1328 doi: 10.1136/bmj.h1328 (Published 1 April 2015) Page 3 of 3PRACTICEHow patients were involved in the creation of this article• We approached patients from the Liverpool “Joint Clinic” and the Bruneck Centre for Mental Health, Italy, where many patients withdelusional infestation are seen• We have integrated their responses and priorities into our recommendationsFor personal use only: See rights and reprints http://www.bmj.com/permissions Subscribe: http://www.bmj.com/subscribeBMJ 2015;350:h1328 doi: 10.1136/bmj.h1328 (Published 1 April 2015) Page 4 of 3PRACTICE

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How to approach delusional infestation

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