Pitfalls and Pearls in Delusional Parasitosis

Abstract

Delusional parasitosis is an uncommon psychiatric disorder that manifests as having parasitic delusions. Due to its rarity, delusional parasitosis is a challenging and costly diagnosis of exclusion and proves difficult to manage for many providers. Although this syndrome is frequently discussed in psychiatric and dermatology reports, it is not commonly described in emergency medicine (EM) literature. As a result, best practices for workup and treatment remain unclear from an EM perspective. Patients typically return multiple times for medical evaluation and exhaust numerous resources. In this case report we review the appropriate steps for initial evaluation of patients with suspected delusional parasitosis, differential diagnoses, and increase awareness for prudent treatment strategies.

A Longitudinal Case of Shared Delusional Infestation

“…Delusional infestations pose a challenge to ED providers. These disorders are often a diagnosis of exclusion, lack clear acute diagnostic and treatment recommendations, and commonly generate recurrent visits with fragmented healthcare and disproportionate resource utilization [ 7 ]. When entertaining a diagnosis of delusional infestation, it is imperative to determine whether the patient has a “shakable” or “unshakable” belief in their infestation.…”

“…The differential diagnosis for organic causes of such symptoms includes traumatic brain injury, cerebrovascular disease, dementia, other cognitive impairments, thyroid dysfunction, nutritional deficiencies, diabetes, recreational drug intoxication, chronic substance abuse and/or withdrawal, drug reactions/allergies, human immunodeficiency virus, and actual parasitic infestations [ 9 ]. Initial diagnostic testing available in the ED includes complete blood count with differential (primarily to screen for eosinophilia); complete metabolic panel (including glucose, urea, and liver function); serum levels of thyroid stimulating hormone, B12, and folic acid; urine toxicology; syphilis screening; human immunodeficiency virus testing; and non-contrast computed tomography (CT) head [ 7 ]. Biopsy and pathology testing are typically deferred to the PCP or outpatient specialty clinic.…”

“…Within this patient-provider relationship, the provider works to build a therapeutic alliance by remaining non-judgmental, acknowledging but not necessarily agreeing with the delusions, and providing consistent reassurance of a negative workup with transparency of testing results (e.g., serum laboratory testing, pathology, imaging, etc.) [ 7 ]. Any patient diagnosed with a delusional disorder should be carefully assessed for comorbid pre-existing or superimposed psychiatric conditions.…”

Primary psychiatric disorders

“…In terms of treatment options for DP, extensive review of literature supports the use of first or second‐generation antipsychotic agents, whereas second‐generation agents are less likely to induce extrapyramidal effects 15 . Quetiapine, olanzapine, risperidone, pimozide have been effectively used but compliance with treatment is problematic in delusional patients.…”