Excerpt from Delusions of Parasitosis

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Background

Delusions of parasitosis (DP) manifest in the patient's firm belief that he or she has pruritus due to an infestation with insects. Patients may present with clothing lint, pieces of skin, or other debris contained in plastic wrap, on adhesive tape, or in matchboxes. They typically state that these contain the parasites; however, these collections have no insects or parasites. This presentation is called the matchbox sign, or what the authors term the "Saran-wrap sign."

The patients have no obvious cognitive impairment, and abnormal organic factors are absent. True infestations and primary systemic diseases that cause pruritus are not involved. Primary skin lesions are not present. Physical examination may reveal no lesions, but only linear erosions with crusts, prurigo nodularis, and/or ulcers.

The classification of DP is complicated. It is considered primarily a monosymptomatic hypochondriacal psychosis and has been associated with schizophrenia, obsessional states, bipolar disorder, depression, and anxiety disorders. DP occurs primarily in white middle-aged or older women, although it has been reported in all age groups and in men.

Medscape Resource Centers for Schizophrenia, Bipolar Disorder, Depression, and Anxiety Disorders may provide helpful additional information.

Savely et al¹ introduced the term Morgellon disease to describe a condition characterized by fibers attached to the skin. The entity appears to be little more than a new designation for DP. Koblenzer² and Waddell and Burke³ have discussed the utility of the term, with Murase et al⁴ finding the term useful for building a therapeutic alliance with patients with DP. The Centers for Disease Control and Prevention is currently investigating Morgellon disease.⁵

William Harvey⁶ of the Morgellons Research Foundation Medical Advisory Board states the following:

All patients with Morgellons carry elevated laboratory proinflammatory markers, elevated insulin levels, and verifiable serologic evidence of 3 bacterial pathogens. They also show easily found physical markers such as peripheral neuropathy, delayed capillary refill, abnormal Romberg’s sign, decreased body temperature, and tachycardia. Most importantly they will improve, and most recover on antibiotics directed at the above pathogens.

Pathophysiology

The cause of DP is unknown. It appears related to neurochemical pathology. This concept is underlined by its induction by psychoactive agents (eg, amphetamines, cocaine, and methylphenidate) and its coincidence with depression, schizophrenia, social isolation, and sensory impairment.

Frequency

United States

The exact prevalence of DP is unknown.

International

The exact prevalence of DP is unknown.

Mortality/Morbidity

The literature includes one report of suicide in a 40-year-old man with DP.⁸

Race

DP appears to be more common in whites than in people of other races.

Sex

DP occurs primarily in white middle-aged or older women, although it has been reported in all age groups and in men. The female-to-male ratio is approximately 2:1. More specifically, this ratio is 1:1 in people younger than 50 years and 3:1 in those older than 50 years.

Age

This disease is more common in middle-aged and elderly persons than in others. The male-to-female ratio is 1:1 in people younger than 50 years and 3:1 in those older than 50 years.

Please click here to view the full topic text: Delusions of Parasitosis