Delusional parasitosis

Delusional parasitosis is a form of psychosis in which sufferers hold a delusional belief they are infested with parasites. It is usually diagnosed as a subtype of delusional disorder. A related symptom involving a tactile hallucination of insects, snakes, or other vermin crawling over the skin is known as formication. The origin of this word is from the Latin formica, "ant".

Delusional parasitosis is also referred to as "Ekbom's Syndrome", named after a Swedish neurologist, Karl Axel Ekbom, who published seminal accounts of the disease in 1937 and 1938. It is not to be confused with Wittmaack-Ekbom syndrome (restless legs syndrome).

Presentation

The sufferer typically reports parasites to exist under the skin, around or inside bodily openings, in the stomach or bowels and may include a belief that the parasites infest the sufferer's home, surroundings or clothing.

A person holding such a belief may approach doctors or dermatologists asking for treatment for the supposed infestation, and will often bring small particles, dust, skin flakes and other material for the doctor to inspect. Since the material may be carried in an envelope or matchbox, this presentation is known as the "matchbox sign".

Stimulant drug abuse (particularly amphetamine and cocaine) can lead to delusional parasitosis as part of a stimulant psychosis. For example, excessive cocaine use can lead to an effect nicknamed "cocaine bugs" where the affected person believes that they can feel parasites crawling under their skin. These conditions are also associated with high fevers and extreme alcohol withdrawal (Delirium tremens), often associated with visual hallucinations of insects.

People suffering from these conditions may scratch themselves to the extent of serious skin damage and bleeding, especially if they are delirious or intoxicated.

Treatment

If due to stimulant abuse, the primary treatment is to cease the use of stimulants. The chronic condition is treated much as other delusional disorders and schizophrenia. In the past, pimozide was the drug of choice when selecting from the typical antipsychotics. Currently, atypical antipsychotics such as olanzapine or risperidone are used as first line treatment.

Fictional accounts

• A fictional account of delusional parasitosis is given in the opening chapter of Philip K. Dick's novel A Scanner Darkly.
• A character in the movie Oldboy suffers a one-time attack of delusional parasitosis.
• A secondary character in the movie Hellraiser II also suffers from severe chronical delusional parasitosis.
• The lead character in John Irving's The Fourth Hand reports formication on the stump of his amputated left hand.

See also

• Amphetamine psychosis
• Delusion
• Delusional disorder
• Morgellons
• Parasite
• Psychosis

External links

• The Bohart Museum of Entomology Human Skin Parasites & Delusional Parasitosis
• Ekbom, K.A. (2003) The pre-senile delusion of infestation (Classic text no. 54). History of Psychiatry, 14 (2), 229-256.
• Delusions of Intestinal Parasitosis
• Delusory Parasitosis Nancy C. Hinkle, American Entomologist, vol 46, number 1.
• Delusions of Parasitosis Noah S. Scheinfeld, eMedicine Clinical Knowledge Base, updated January 12, 2006.

References

• Enoch, D. & Ball, H. (2001) Ekbom's Syndrome (Delusional parasitosis). In Enoch, D. & Ball, H. Uncommon psychiatric syndromes (Fourth edition) pp209-223. London: Arnold. ISBN 0340763884