The authors’ observations
Delusional parasitosis is a rare disorder that is defined by an individual having a fixed, false belief that he or she is being infected or grossly invaded by a living organism. Karl A. Ekbom, a Swedish neurologist, was the first practitioner to definitively describe this affliction in 1938.1
Primary delusional parasitosis is a disease defined by this single psychotic symptom without other classic symptoms of schizophrenia; this single symptom cannot be attributed to the effects of substance abuse or a medical condition. Many affected patients remain functional in their daily lives; only a minority of patients experience delusions that interfere with usual activity.2 Secondary delusional parasitosis is a symptom of another psychiatric or medical disease.
Morgellons disease is characterized by symptoms similar to primary delusional parasitosis, but symptoms of this condition also include the delusional belief that inanimate objects, usually fibers, are in the skin as well as the parasites.3
A population-based study among individuals living in Olmsted County, Minnesota from 1976 to 2010 found that the incidence of delusional infestation was 1.9 cases (95% confidence interval, 1.5 to 2.4) per 100,000 person-years.4 In a retrospective study of 147 patients with delusional parasitosis, 33% of these patients described themselves as disabled, 28% were retired, and 26% were employed.5 In this study, the mean age of diagnosis was 57, with a female-to-male ratio of 2.89:1.5
Continue to: HISTORY Prior psychiatric hospitalization