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Delusional parasitosis: Epidemiology, clinical presentation, assessment and diagnosis

Authors
Kathryn N Suh, MD, FRCPC
Jay S Keystone, MD, MSc (CTM), FRCPC
Section Editor
Stephen Marder, MD
Deputy Editor
Richard Hermann, MD

INTRODUCTION

Delusional parasitosis is a rare disorder in which affected individuals have the fixed, false belief (delusion) that they are infected by "bugs": parasites, worms, bacteria, mites, or other living organisms. As with all delusions, this belief cannot be corrected by reasoning, persuasion, or logical argument. Many affected individuals are quite functional; for the minority, delusions of parasitic infection may interfere with usual activities [1].

Delusional parasitosis is a delusional disorder of the somatic type [2], a subgroup of delusional disorders in which nonexistent disease or alteration of the body forms the basis of the disorder. Delusions of parasitosis are the most common form of monosymptomatic hypochondriacal psychosis; others include delusions of dysmorphism and delusions of body odor or halitosis.

This topic addresses the epidemiology, clinical presentation, and diagnosis of delusional parasitosis. Treatment of delusional parasitosis is discussed separately. Other psychotic disorders are discussed separately. First and second-generation antipsychotic drugs are discussed separately. (See "Treatment of delusional parasitosis" and "Brief psychotic disorder" and "Postpartum psychosis: Epidemiology, clinical manifestations, assessment, and diagnosis" and "Schizophrenia: Clinical manifestations, course, assessment, and diagnosis" and "Pharmacotherapy for schizophrenia: Acute and maintenance phase treatment" and "First-generation antipsychotic medications: Pharmacology, administration, and comparative side effects" and "Second-generation antipsychotic medications: Pharmacology, administration, and side effects".)

TERMINOLOGY

Delusional parasitosis — Delusional parasitosis is known by numerous other names, including Ekbom syndrome, delusory parasitosis, psychogenic parasitosis, delusional infestation, delusional ectoparasitosis, formication, chronic tactile hallucinosis, dermatophobia, parasitophobia, and cocaine bugs. The term "delusional parasitosis" was introduced in 1948 in a description of 45 cases [3]. More recent literature refers to delusional infestation.

Two forms of delusional parasitosis are widely recognized [4,5]:

                   

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