Journal of the Louisiana State Medical Society
Delusional Infestations: Case Series, Differential Diagnoses, and Management Strategies
James H. Diaz, MD, MPH&TM, DrPH; Lee T. Nesbitt Jr., MD
Physicians are not infrequently consulted by distraught patients with delusions of infestation who believe that they are infested with external or internal parasites and describe a crawling sensation of bugs or worms on or under their skin. Internet search engines were queried with the keywords as search terms to examine the latest articles on delusional infestations in order to describe presenting manifestations, differential diagnoses, and effective management strategies. The demographic and behavioral features of delusional infestations have remained constant and include: (1) onset in well-educated, middle-aged adults who are pet owners; (2) production of purported specimens of causative parasites; (3) pesticide overtreatment of themselves, their households, and pets; (4) excessive cleaning or vacuuming of households; (5) intense anger and resentment directed at physicians failing to confirm their self-diagnoses; and (6) sharing delu- sional symptoms with spouses or relatives. Although some reports have suggested that cases of delusional infestation are increasing today in the tropics, most studies have confirmed a stable incidence over time and similar disorder demographics worldwide. However, management strategies for delusional infestations have changed significantly over time with second generation, atypical antipsychotics offering safer adverse effect profiles and better prognoses than earlier therapies with first generation, typical antipsychotics. The most effective management strategies for delusional infestations include empathetic history-taking and ac- tive listening to the patient, careful exclusion of true parasitoses, and a therapeutic regimen that includes a second generation neuroleptic agent.
In an era of Internet-assisted self-diagnoses and the return of bedbugs, physicians are not infrequently consulted by distraught patients who believe that they are infested with external or internal parasites, describe a crawling sen- sation of bugs or worms on or under their skin, and often display a boxed specimen or blurred photo of the offend- ing parasite. When other causes of infectious dysesthesias - such as scabies, cercarial dermatitis, and cutaneous larva migrans - are excluded by physical examination or skin biopsy, and no treatable dermatoses are diagnosed, this con- dition is called delusional infestation, formerly delusional parasitosis. The objectives of this review are to present a representative series of cases of delusional infestations and to recommend effective management strategies. METHODS Internet search engines were queriedwith the keywords as search terms to examine the latest scientific articles on delusional infestations in order to describe a variety of clinical and behavioral manifestations, develop a differential diagnosis, and recommend new and effective management
strategies. The keywords included the following: parasit- osis, delusional; ectoparasitosis, delusional; infestations, delusional; Ekbom’s syndrome; acarophobia; and Morgel- lons disease. A representative series of cases, either from peer-reviewed scientific publications, or from the authors’ own clinical practices are reported first. RESULTS
Report of Cases
Case 1 (Adapted from Meehan WJ et al. 2006) 1 A 56-year-old female with a history of depression presented with a two-month history of intensely pruritic sensations of “bugs that were crawling” on her posterior neck at her hairline. These sensations were resistant to topical therapy with antihistamines and corticosteroids. Physical examination demonstrated a localized plaque of self-excoriated nodules and papules. Microscopic exami- nation of skin scrapings was negative for scabies mites or eggs, and a potassium hydroxide mount was negative for any organisms or fungi. Intralesional triamcinolone was in-
154 J La State Med Soc VOL 166 July/August 2014
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