Delusional parasitosis: six-year experience with 23 consecutive cases at an academic medical center

Delusional parasitosis is a syndrome with which most infectious diseases physicians and microbiologists are familiar. However, little is known about the epidemiology of this disorder, and most reports consist of case reports or small series. We conducted a case series with long-term questionnaire follow-up of delusional parasitosis patients presenting to our academic medical center.

From 1994 through 1999, 23 patients with primary delusional parasitosis (as defined by DSM IV criteria) were identified through the Infectious Diseases Clinic or Emergency Room at the University of Washington and cases were analyzed for prospectively established demographic, clinical, and social variables of interest.

Of 23 patients, 15 were women and eight were men. Mean duration (+/- standard deviation) of symptoms was 2.6+/-2.8 years (median 1.5), with shorter duration related to improved prognosis. Mean symptom duration in women was 3.1+/-3.0 years versus 1.5+/-1.5 years in men. Patients saw an average of six physicians before presenting to our center. Reduced social interactions were common, but employment affect was not significant. Treatment with pimozide or gabapentin combined with antidepressants appeared to be effective in some cases.

This is the largest study of primary delusional parasitosis originating from an academic medical center, and highlights the burden of disease borne by patients and the healthcare system.