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 another form of this condition, with nonspecific “fibers” as the infective agent.
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 his 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.
A study conducted of 108 patients at the Mayo Clinic was published in Archives of Dermatology on May 16, 2011. The study failed to find evidence of skin infestation despite doing skin biopsies and examining specimens provided by the patients. The study, which was conducted between 2001 and 2007, concluded that the feeling of skin infestation was delusional parasitosis.
Delusional parasitosis is seen more commonly in women, and the frequency is much higher past the age of 40.
Delusory cleptoparasitosis is a form of delusion of parasitosis where the person believes the infestation is in their dwelling, rather than on or in their body.
Morgellons is poorly understood but appears to be a form of delusional parasitosis in which people have painful skin conditions that they believe contain fibers of various kinds.
Content retrieved from: https://en.wikipedia.org/wiki/Delusional_parasitosis.