DermNet provides Google Translate, a free machine translation service. Note that this may not provide an exact translation in all languages
Author: Vanessa Ngan, Staff Writer, 2005.
As the name suggests delusions of parasitosis is a condition where an individual has the mistaken belief that they are being infested by parasites such as mites, lice, fleas, spiders, worms, bacteria, or other organisms.
Delusions of parasitosis are sometimes called delusional infestation, pseudoparasitic dysaesthesia, or parasitophobia. It is closely related to Morgellons disease, in which an individual feels they have fibres coming out of their skin.
The cause of delusions of parasitosis is unknown but it has been classified as a monosymptomatic hypochondriacal psychosis. This term is used to describe patients with a single fixed hypochondriacal delusion sustained over a considerable period but not secondary to another psychiatric illness. Apart from their delusions of parasitosis, patients may have an otherwise normal personality, or more commonly, an acceptable degree of eccentricity with a tendency towards social isolation.
Delusions of parasitosis have also been associated with other psychiatric illnesses including schizophrenia, obsessional states, depression, bipolar disorder and anxiety disorders. This is known as secondary delusions of parasitosis.
Delusions of parasitosis occur most commonly in white middle-aged or older women, although people of all races, sex and age can be affected.
People suffering from delusions of parasitosis often describe the infestation as being in or under the skin, just inside body openings or in sputum, inside their stomach or intestines, and in their surrounding habitat such as their bed, couch or throughout their home.
Characteristic symptoms of delusions of parasitosis include:
One or more family members sometimes share delusions of parasitosis. When two family members are involved, usually husband and wife or parent and child, the delusion is known as folie à deux (craziness of 2).
Complete physical examination and appropriate laboratory tests can help to identify other diseases that mimic the delusions of parasitosis and rule out any true infestations, e.g. with scabies or lice.
A history of drug abuse with cocaine, methylphenidate, or amphetamines must also be ascertained as these substances can induce the sensation of itchiness and result in skin picking.
The management of patients with delusions of parasitosis is often difficult as they are totally convinced of the existence and infestation of “their” parasites. Sometimes the disease may get better and go away on its own but in most cases, treatment with psychotropic medications is usually necessary. Often management of these patients is best handled through the cooperation of dermatologists, psychiatrists and entomologists. The following points should be taken into consideration when treating a patient.
See the DermNet NZ bookstore
© 2020 DermNet New Zealand Trust.
DermNet NZ does not provide an online consultation service. If you have any concerns with your skin or its treatment, see a dermatologist for advice.