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Treatment of delusional infestation

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


Delusional infestation (also called delusional parasitosis [1]) is a rare disorder in which affected individuals have the fixed, false belief (delusion) that they are infected by "bugs": parasites, worms, bacteria, fungi, mites, or other living organisms, or “fibers.” 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, and for some very significantly [2].

Delusional infestation is a delusional disorder of the somatic type [3], a subgroup of delusional disorders in which nonexistent disease or alteration of the body forms the basis of the disorder. Delusions of infestation 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 treatment of delusional infestation. The epidemiology, clinical presentation, and diagnosis of delusional infestation are discussed separately. Other psychotic disorders are discussed separately. First- and second-generation antipsychotic drugs are discussed separately. (See "Delusional infestation: Epidemiology, clinical presentation, assessment and diagnosis" and "Postpartum psychosis: Epidemiology, pathogenesis, clinical manifestations, course, assessment, and diagnosis" and "First-generation antipsychotic medications: Pharmacology, administration, and comparative side effects" and "Second-generation antipsychotic medications: Pharmacology, administration, and side effects" and "Pharmacotherapy for schizophrenia: Acute and maintenance phase treatment" and "Pharmacotherapy for schizophrenia: Side effect management".)


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

Primary delusional infestation – Primary delusional infestation is a psychiatric disorder with the delusion of parasitic infection as its only manifestation.

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Literature review current through: Nov 2017. | This topic last updated: Dec 01, 2017.
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