As the name suggests, delusions of parasitosis (DOP) 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. They have a fixed false belief that they are infested and they usually go from doctor to doctor seeking a cure.

DOP is closely related to the so-called Morgellons syndrome, in which an individual believes that they have fibers coming out of their skin.

The cause of DOP is unknown but it has been classified as a monosymptomatic hypochondrial psychosis. Apart from their DOP, patients may have an otherwise normal personality or more commonly an acceptable degree of eccentricity with a tendency toward social isolation. It can also occur as a manifestation of other psychiatric illnesses.

DOP occurs most commonly in white middle-aged or older women, although people of all races, sex, and age may be affected.

People suffering from DOP often describe the infestation as being in or under the skin, just inside body openings, in sputum, inside their stomach, intestines or on their surrounding habitat such as their bed, couch, or throughout their home.

The patient typically seeks numerous opinions from medical doctors, exterminators, and entomologists.

The patient typically brings fragments of skin, hair, dried blood, or scabs in a container.

Patients are often hostile or suspicious.

Sensations of itching, burning, crawling and biting that may lead to self-mutilation.

One or more family members sometimes share DOP ( folie à deux).

Rule out any true infestations, for example, with scabies.