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 .
Delusional parasitosis is a delusional disorder of the somatic type , 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 treatment of delusional parasitosis. The epidemiology, clinical presentation, and diagnosis of delusional parasitosis are discussed separately. Other psychotic disorders are discussed separately. First and second-generation antipsychotic drugs are discussed separately. (See "Delusional parasitosis: Epidemiology, clinical presentation, assessment and diagnosis" and "Postpartum psychosis: Epidemiology, clinical manifestations, assessment, and diagnosis" and "First-generation antipsychotic medications: Pharmacology, administration, and comparative side effects" and "Second-generation antipsychotic medications: Pharmacology, administration, and comparative side effects" and "Pharmacotherapy for schizophrenia: Acute and maintenance phase treatment" and "Pharmacotherapy for schizophrenia: Side effect management".)
Two forms of delusional parasitosis are widely recognized [3,4]:
Primary delusional parasitosis — Primary delusional parasitosis is a psychiatric disorder with the delusion of parasitic infection as its only manifestation.