Delusional parasitosis, also known as delusional infestation or Ekbom's syndrome, is a delusional disorder in which individuals incorrectly believe they are infested with parasites, insects, or bugs, whereas in reality no such infestation is present. Individuals with delusional parasitosis usually report tactile hallucinations known as formication, a sensation resembling insects crawling on or under the skin.
Delusional parasitosis is a mental disorder characterized by a fixed, false belief that a skin infestation exists, which is in contrast to cases of actual parasitosis, such as scabies and infestation with Demodex, in which a skin infestation is present and identifiable by a physician through physical examination or laboratory tests.
The alternative name, Ekbom's syndrome, was named after Swedish neurologist Karl-Axel Ekbom, who published seminal accounts of the disease in 1937 and 1938. It is differentiated from Willis–Ekbom disease (WED), another name for restless legs syndrome. Morgellons is a self-diagnosed form of this condition, in which individuals have sores that they believe contain some kind of fibers.
Signs and symptoms
Details of delusional parasitosis vary among sufferers, though it typically manifests as a crawling and pin-pricking sensation that is most commonly described as involving perceived parasites crawling upon or burrowing into the skin, sometimes accompanied by an actual physical sensation (known as formication; often associated with menopause, or sometimes exposure to household cleaning products). Sufferers may injure themselves in attempts to be rid of the "parasites". Some are able to induce the condition in others through suggestion, in which case the term folie à deux may be applicable.
Nearly any marking upon the skin, or small object or particle found on the person or their clothing, can be interpreted as evidence for the parasitic infestation, and sufferers commonly compulsively gather such "evidence" and then present it to medical professionals when seeking help. This presentation of "evidence" is known as "the matchbox sign" because the "evidence" is frequently presented in a small container, such as a matchbox.
Archives of Dermatology on May 16, 2011 published a Mayo Clinic study of 108 patients. It failed to find evidence of skin infestation despite doing skin biopsies and examining patient-provided specimens. The study, conducted from 2001 to 2007, concluded that the feeling of skin infestation was delusional parasitosis.
Delusional parasitosis is divided into primary, secondary functional, and secondary organic groups.
In primary delusional parasitosis, the delusions make up the entire disease entity: no additional deterioration of basic mental functioning or idiosyncratic thought processes exist. The parasitic delusions consist of a single delusional belief regarding some aspect of health. Medical experts refer to this phenomenon as "monosymptomatic hypochondriacal psychosis", and sometimes as "true" delusional parasitosis. In the DSM-IV, it corresponds with "delusional disorder, somatic type".
Secondary organic delusional parasitosis occurs when a medical illness or substance (medical or recreational) use causes the patient's symptoms. In the DSM-IV this situation corresponds with "psychotic disorder due to general medical condition". Physical illnesses that can underlie secondary organic delusional parasitosis include: hypothyroidism, cancer, cerebrovascular disease, tuberculosis, neurological disorders, vitamin B12 deficiency, and diabetes mellitus. Any illness or medication for which formication is a symptom or side effect can become a trigger or underlying cause of delusional parasitosis.
Other physiological factors which can cause formication and thus can sometimes lead to this condition include: menopause (i.e. hormone withdrawal); allergies, and drug abuse, including but not limited to cocaine abuse and methamphetamine (as in amphetamine psychosis). It appears that many of these physiological factors, as well as environmental factors such as airborne irritants, are capable of inducing a "crawling" sensation in otherwise healthy individuals; however, some people become fixated on the sensation and its possible meaning, and this fixation may then develop into delusional parasitosis.
Secondary forms of delusional parasitosis are addressed by treatment of the primary associated psychological or physical condition. The primary form 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.
Notably, sufferers often will reject the professional medical diagnosis of delusional parasitosis, and few patients willingly undergo treatment, despite demonstrable efficacy.
Society and culture
The founder of the Morgellons Research Foundation, Mary Leitao, coined the name in 2002, reviving it from a letter written by a physician in the mid-1600s. Leitao and others involved in her foundation (who self-identified as having Morgellons) successfully lobbied members of the U.S. Congress and the U.S. Centers for Disease Control and Prevention (CDC) to investigate the condition in 2006. CDC researchers issued the results of their multi-year study in January 2012, indicating that no disease organisms were present in people with Morgellons; the fibers found were likely cotton, concluding that the condition was "similar to more commonly recognized conditions such as delusional infestation".
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