Delusional parasitosis

Delusional parasitosis (DP), also called delusional infestation, is a mental health condition where a person falsely believes that their body is infested with living or nonliving agents. Common examples of such agents include parasites, insects, or bacteria. This is a delusion due to the belief persisting despite evidence that no infestation is present. People with this condition may have skin symptoms such as the urge to pick at one's skin (excoriation) or a sensation resembling insects crawling on or under the skin (formication). Morgellons disease is a related constellation of symptoms. This self-diagnosed condition is considered a form of a type of delusional parasitosis. People with Morgellons falsely believe harmful fibers are coming out of their skin and causing wounds.

Delusional parasitosis is classified as a delusional disorder in the fifth revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). The precise cause is unknown. It may be linked to problems with dopamine in the brain, similar to psychotic disorders. Diagnosis requires the delusion to be the only sign of psychosis, not caused by another medical condition, and present for at least a month. A defining characteristic of delusions is that the false belief cannot be corrected. As a result, most affected individuals believe their delusion is true and do not accept treatment. Antipsychotic medications can help with symptom remission. Cognitive behavioral therapy and antidepressants can also decrease symptoms.

The condition is rare and affects women twice as often as men. The average age of individuals affected by the disorder is 57. Ekbom's syndrome is another name for the condition. This name honors the neurologist Karl-Axel Ekbom, who published accounts of the disease in 1937 and 1938.